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Biological and Physical Factors Affecting Catch of House Flies in Ultraviolet Light Traps

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Biological and Physical Factors Affecting Catch of House Flies in Ultraviolet Light Traps
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2008

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Artificial flies ( jstor )
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Houses ( jstor )
Insects ( jstor )
Lighting ( jstor )
Luminous intensity ( jstor )
Spectroscopy ( jstor )
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Visible spectrum ( jstor )

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BIOLOGICAL AND PHYSICAL FACTORS AFFECTING CATCH OF HOUSE FLIES
IN ULTRAVIOLET LIGHT TRAPS















By

MATTHEW D. AUBUCHON


A DISSERTATION PRESENTED TO THE GRADUATE SCHOOL
OF THE UNIVERSITY OF FLORIDA IN PARTIAL FULFILLMENT
OF THE REQUIREMENTS FOR THE DEGREE OF
DOCTOR OF PHILOSOPHY

UNIVERSITY OF FLORIDA


2006

































Copyright 2006

by

Matthew D. Aubuchon















ACKNOWLEDGMENTS

I would like to sincerely thank Dr. Phil G. Koehler for directing the course of this

dissertation and my graduate program. I would also like to acknowledge and thank Dr.

Faith Oi, Dr. Norm Leppla, Dr. Nancy Hinkle, Dr. Jerry Hogsette, and Dr. Ron Randles

for their service on my supervisory committee. Ricky Vasquez, Ryan Welch, and Jeff

Hertz provided valuable assistance with house-fly rearing. Dr. Phil Kaufman graciously

made space in his laboratory for us to rear our house flies and provided valuable rearing

advice. Debbie Hall was extraordinarily helpful to me with registration, research credits,

graduate-school deadlines, and all other associated paperwork. I would like to thank my

family for their support through this process. Finally, I would like to thank my beautiful

wife Amanda for her love, support, encouragement, and patience throughout my graduate

school experience.
















TABLE OF CONTENTS

page


A C K N O W L E D G M E N T S ................................................................................................. iii

L IST O F T A B L E S ........ ....................................................... .. .... ...... ...... ....... vi

L IST O F F IG U R E S .... ...... ................................................ .. .. ..... .............. vii

A B STR A C T ................................................. ..................................... .. x

CHAPTER

1 INTRODUCTION AND LITERATURE REVIEW ....................................................1

The House Fly M usca domestica.................................. .................. .........
Importance of M usca domestic ......... .... .............................. ...................
Nuisance .......... .... ....... ..............................1
D disease Transm mission ............................................ ... .. ....... .......... ...... .
B iology ofM usca dom estica ........................................ ....................................... 4
Oviposition ....................................... ...............
Larval D evelopm ent and Survival ......................................... .......................... 4
A dult B behavior ....................................................... 6
Activity and longevity .................. .............................. 6
P h oto p erio d ....................................................... 7
Dispersal ........... .... .... ........ .............. ...................8
Attractants for Musca domestic ............................ .................. ......... 9
C hem ical A ttractants ................................................ .... ........ .................
Physical Attractants .............................. ... ............... 9
C olor ...................................................... . 9
Surfaces ......... ... .............. .. ............................ 10
L eight ......... ........................................................................ 11
Control Using Attractants ..... ........................................................ ... 13
C h e m ic a l B a its ............................................................................................... 1 3
P h y sical T rap s .........................................................................................13
Insect Light Traps (ILT) ......................................................... .............. 14
House Fly Response to ILTs ............... .............. ..... .. ... ............... 14
D esign and Location of ILTs ...................... ......... ............ ............... 15
Competing Light Sources ............... ........................................... 16
State ent of Purpose ........ ....... .............. .. ........... .......... ..... 18









2 ESTIMATES OF RESPONSE TIME BY HOUSE FLIES TOWARD UV LIGHT
TRAPS USING LIGHT-TUNNEL BIOASSAY ..................... ............................ 20

In tro du ctio n ...................................... ................................................ 2 0
M materials and M methods ....................................................................... ..................2 1
R results and D iscu ssion .............................. ........................ .. ...... .... ...... ...... 25

3 INFLUENCES OF QUALITY AND INTENSITY OF BACKGROUND LIGHT
ON HOUSE FLY RESPONSE TO LIGHT TRAPS ................................................37

Intro du action ...................................... ................................................ 3 7
M materials and M methods ....................................................................... ..................38
R results and D iscu ssion .............................. ........................ .. ...... .... ...... ...... 43

4 LIGHT TRAP HABITUATION STUDY ...................................... ............... 63

Intro du action ...................................... ................................................ 6 3
M materials and M methods ....................................................................... ..................63
R results and D iscu ssion .............................. ........................ .. ...... .... ...... ...... 67

5 SUMMARY AND CONCLUSIONS.......................................................................73

APPENDIX

A DIAGRAM OF BUILDING LAYOUT .......................................... ............... 76

B SAS PROGRAMS USED FOR DATA ANALYSIS .............................................77

SA S program s for C chapter 2 ............................................ .....................................77
SA S program s for C chapter 3............................................. ....................................79
SA S Program s for Chapter 4 ............................................ ............................... 81

C SPECTROMETRY MEASUREMENTS FOR LIGHT TRAPS AND
BACKGROUND LIGHT ............................................................. ............... 82

D REARING CONDITIONS FOR CONLONIES OF MUSCA DOMESTIC ............90

L IST O F R E F E R E N C E S ......... .. ............... ................. ................................................96

B IO G R A PH ICA L SK ETCH ......... ................. ...................................... .....................105















LIST OF TABLES


Table p

2-1 Effect of building, position within building, and box enclosure on the number of
house flies caught in UV light traps (50 M: 50 F per repetition). ..........................30

2-2 Influence of age and sex on number of house flies caught in UV light traps (50 M:
50 F per repetition) .......................................................... .. ............

2-3 Cumulative house-fly catch in UV light traps over time (50 M: 50 F per repetition)32

2-4 Estimated time (h) to catch of adult house flies by UV light traps using Probit
an aly sis .................................................. ....... ................. 3 3

3-1 Light intensity (lumens/m2) measured within five local restaurants (R) and grocery
stores (G) ............. ............................................. .. ......... 48

3-2 Light intensity (lumens/m2) of four intensity treatments of cool-white fluorescent
light m measured 45 cm from light source............................................... ............. 48

3-3 Effect of intensity of cool-white fluorescent light as a competing light source on
number of adult house flies (mean SE) caught in UV light traps (50 M: 50 F per
re p etitio n ) ......................................................................... 4 9

3-4 Estimated intensity (lumens/m2) of total spectral output, blue-green output, and
ultraviolet output emitted from competing light sources and light traps used in light
quantity experim ents ...................... ................ ............................ 50

3-5 Effect of competing light quality on mean number ( SE) of adult house flies
caught in UV light traps (50 M : 50 F per repetition) ............................................ 51

3-6 Estimated intensity (lumens/m2) of total spectral output, blue-green output, and
ultraviolet output emitted from competing light sources and light traps used in light
qu ality ex p erim en ts ....................................................................... .................... 52

4-1 Mean number of adult house flies caught in UV light traps after being pre-
conditioned under different light conditions. ................................ ..................69















LIST OF FIGURES


Figure page

2-1 Light tunnel design illustrating release cage (30 by 30 by 45 cm) (foreground),
overhead light source (101.6 cm), light tunnel (152 by 20 cm), and box enclosure
(66 by 91 by 60 cm) containing light trap........ .............................................. 34

2-2 Intensity (lumens / m2) of UV-light trap with relative intensity of light by
w av e le n g th ...............................................................................................................3 5

2-3 Intensity (lumens/m2) of cool-white fluorescent light with relative intensity of light
by w avelength ........................................................................36

3-1 Spectral analysis and mean intensity (lumens/m2) of 1 Sylvania Cool White
fluorescent bulb measured at 61 cm from source. Arrow highlights blue-green peak
b etw een 4 80 an d 5 10 nm ............................................................... .....................53

3-2 Spectral analysis and mean intensity (lumens/m2) of 2 Sylvania Cool White
fluorescent bulbs measured at 61 cm from source. Arrow highlights blue-green
peak betw een 480 and 510 nm ..................................................... .....................54

3-3 Spectral analysis and mean intensity (lumens/m2) of 3 Sylvania Cool White
fluorescent bulbs measured at 61 cm from source. Arrow highlights blue-green
peak betw een 480 and 510 nm ..................................................... .....................55

3-4 Spectral analysis and mean intensity (lumens/m2) of 4 Sylvania Cool White
fluorescent bulbs measured at 61 cm from source. Arrow highlights blue-green
peak betw een 480 and 510 nm ..................................................... .....................56

3-5 Regression analysis showing relationship between trap catch and intensity
(lumens/m2) of blue-green light........................... ......... ............. ....... 57

3-6 Spectral analysis and mean intensity (lumens/m2) of Sylvania Blacklight bulbs
measured at 61 cm from source. Arrow highlights UV peak between 340 and 370
n m ................... .......................................................... ................ 5 8

3-7 Spectral analysis and mean intensity (lumens/m2) of Sylvania Daylight fluorescent
bulbs measured at 61 cm from source. Arrow highlights blue-green peak between
480 and 510 nm ........................................................................59









3-8 Spectral analysis and mean intensity (lumens/m2) of Sylvania Cool White
fluorescent light measured at 61 cm from source. Arrow highlights blue-green
peak betw een 480 and 510 nm ..................................................... .....................60

3-9 Spectral analysis and mean intensity (lumens/m2) of Sylvania Warm White
fluorescent light measured at 61 cm from source. Arrow highlights blue-green
peak betw een 480 and 510 nm ..................................................... .....................61

3-10 Regression analysis showing relationship between trap catch and intensity
(lumens/m2) of blue-green light ............. ......... .......................... 62

4-1 Spectral analysis and mean intensity of GE Plant & Aquarium fluorescent light
used in house fly rearing room. Mean light intensity presented in lumens/m2. ......70

4-2 Spectral analysis and mean intensity of Sylvania Blacklight used to rear treatment
house flies. Mean light intensity presented in lumens/m2 ......................................71

4-3 Spectral analysis and mean intensity of Sylvania Cool White fluorescent light
used to rear treatment house flies. Mean light intensity presented in lumens/m2. ..72

A-i Diagram of buildings, positions, and bioassay layout at USDA..............................76

C-1 Spectral analysis and mean light intensity of Whitmire Nova trap 1 at Position al.82

C-2 Spectral analysis and mean light intensity of Whitmire Nova trap 2 at Position a2.83

C-3 Spectral analysis and mean light intensity of Whitmire Nova trap 3 at Position bl 84

C-4 Spectral analysis and mean light intensity of Whitmire Nova trap 4 at Position b2 85

C-5 Spectral analysis and mean intensity of overhead cool-white fluorescent light at
Position a ................ ...... ............. ....... ... ......................... 86

C-6 Spectral analysis and mean intensity overhead cool-white fluorescent light at
P o sitio n a2 ...........................................................................8 7

C-7 Spectral analysis and mean intensity overhead cool-white fluorescent light at
Position b, .................... ...... ............................... 88

C-8 Spectral analysis and mean intensity overhead cool-white fluorescent light at
P o sition b 2 ...........................................................................89

D-l Temperature (CO) of rearing room for adult Musca domestic recorded by HOBO
Tem p & R H data logger ......... ................. ................. .................. ............... 90

D-2 Relative Humidity (%) of rearing room for adult Musca domestic recorded by
H OB O Tem p & RH data logger........................................ ........................... 91









D-3 Light intensity (lumens/m2) of rearing room for adult Musca domestic recorded by
HOBO Light Intensity data logger. Graph illustrates 12:12 (L:D) photoperiod.....92

D-4 Temperature (C) of rearing room for Musca domestic larvae recorded by HOBO
T em p & R H data logger ............. .................................................. ............... 93

D-5 Relative Humidity (%) of rearing room for Musca domestic larvae recorded by
H O B O Tem p & R H data logger........................................ ................................94

D-6 Light intensity (lumens/m2) of rearing room for Musca domestic larvae recorded
by HOBO Light Intensity data logger. Graph illustrates 12:12 (L:D) photoperiod95















Abstract of Dissertation Presented to the Graduate School
of the University of Florida in Partial Fulfillment of the
Requirements for the Degree of Doctor of Philosophy

BIOLOGICAL AND PHYSICAL FACTORS AFFECTING CATCH OF HOUSE FLIES
IN ULTRAVIOLET LIGHT TRAPS

By

Matthew D. Aubuchon

May 2006

Chair: Phil Koehler
Major Department: Entomology and Nematology

A bioassay for studying light trap efficacy for the house fly Musca domestic L.

(Diptera: Muscidae) was developed to overcome position effects associated with light-

trap placement. After initial studies, no significant effects of position were detected

among two research buildings, four positions, or box enclosures used. The light-tunnel

bioassay provided standardized air movement, trap location, trap distance, and

background light for future experiments investigating house fly age and response time.

House flies that were 5 d and younger showed significantly greater attraction toward UV

light traps than older flies. A probit analysis estimated that catch time for 50% of house

flies (CT5o) toward UV traps ranged from 99 to 114 min for males and females

respectively. Estimated CT50 for total house fly response toward UV light trap was

approximately 1.72 h (103.2 min). The CT90 and CT95 estimates for total house fly catch

were 6.01 h (360.6 min) and 8.57 h (514.2 min) for males and females respectively. No









significant difference between male and female response time was seen by overlapping

95% confidence intervals for CT50, CT90, and CT95.

When flies were presented greater intensity levels of cool-white fluorescent light,

the number of males caught in UV traps significantly decreased when intensity of the

competing light exceeded 51.43 lumens/m2. Significant declines in catch of females

occurred at a lower intensity when the competing light exceeded 27.43 lumens/m2. When

the data were combined, overall results showed that the total catch in UV light traps

decreased significantly as the intensity of competing light source increased. Results of

our lab study showed a significant decrease in response of male and female house flies

toward UV light traps as the intensity of competing fluorescent light was increased.

When house flies were presented four different types of competing light, all

responses were significantly different when compared with the dark control. However,

house fly response toward UV light traps was significantly lower when background light

contained broad-based UV versus background light containing blue-green light.

For habituation experiments, all treatments caught significantly fewer house flies

than the dark control. However, there was no significant difference in the response to

UV light traps among house flies reared on UV light, cool-white fluorescent light, and the

grow-lights used in the rearing rooms. The quality of light used in rearing did not

significantly influence house fly response to UV light traps.














CHAPTER 1
INTRODUCTION AND LITERATURE REVIEW

The House Fly Musca domestic

The house fly Musca domestic L. (Diptera: Muscidae) is a synanthropic filth fly

that breeds in garbage, and animal and human feces (Schoof and Silverly 1954a,

Greenberg 1973, Imai 1984, Graczyk et al. 2001). It is a dull gray insect and may be

identified by four longitudinal stripes on the dorsum of the thorax and a sharp angle on

the fourth longitudinal wing vein (West 1951). The house fly does not bite as it is

equipped with sponging-rasping mouthparts (West 1951, McAlpine 1987).

Musca domestic L. is classified in the order Diptera and family Muscidae

(McAlpine 1987, Borror et al. 1989). Flies in the family Muscidae generally have strong

setae dispersed over the entire body, dull color, and reduced wing veination (West 1951,

McAlpine 1987). The Genus Musca encompasses approximately 24 species with 2

subspecies ofM. domestic (West 1951). Because house flies adapt to human

environments, they are found on all continents except Antarctica (West 1951, McAlpine

1987).

Importance of Musca domestic

Nuisance

House flies are a nuisance in agricultural and urban environments (Cosse and Baker

1996, Moon 2002, Hogsette 2003). Large populations populations originating from

animal manure can cause economic losses in livestock (Axtell 1970, Hogsette and Farkas

2000). Dispersing house flies are pestiferous in residential and commercial areas and









present a public health problem to home and business owners near agricultural areas

(Axtell 1970, Hogsette 2003). Breeding sites such as animal waste and garbage

dumpsters contribute to problems associated with house flies in urban environments

(Schoof and Silverly 1954b, Morris and Hansen 1966).

Disease Transmission

House flies have been implicated as mechanical vectors of a range of enteric

pathogens among animals and humans (Schoof and Silverly 1954a, Greenberg 1973, Imai

1984, Graczyk et al. 2001). Viruses, bacteria, and protozoans cling to house fly wings,

setae, tarsi, and mouthparts and are dislodged onto a variety of surfaces (Graczyk et al.

2001). In poultry houses and dairy units, house flies were a primary vector of Salmonella

spp. (Mian et al. 2002). Salmonella spp. and .\llge/la spp. (which causes morbidity and

mortality associated with infantile gastroenteritis), are also transmitted by house flies to

humans (Bidawid et al. 1978). Levine and Levine (1991) reported that the incidence of

dysentery coincided with the seasonal prevalence of house flies. As house flies acquired

.\,/ge/ll spp. from human feces in open latrines, they contaminated open food markets,

hospitals, slaughter houses, and animal farms (Levine and Levine 1991, Graczyk et al.

2001). A high density of open markets with rotting fish, meats, and vegetable matter

combined with close proximity of food markets to slaughter houses encouraged outbreaks

of house flies (Bidawid et al. 1978). Incidentally, a high density of humans lacking

infrastructure and garbage pick-up compounded the health risks associated with house fly

outbreaks (Bidawid et al. 1978). In addition to Salmonella spp. and .l/ge//Al spp., house

flies transmit other enteric disease organisms such as Campylobacter spp. or

enterohemorrhagic E. coli, which cause morbidity and mortality in humans resulting from

diarrheal illnesses (Graczyk et al. 2001). Helminthic parasites have also been transported









on house fly exoskeletons and rotavirus may be transported on legs and wings, then

dislodged by flight motion (Monzon et al. 1991, Tan et al. 1997).

In hospitals, house flies can play a vital role as vectors of resistant strains of enteric

pathogens among patients (Rady et al. 1992). Pathogens such as Klebsiella spp.,

Enterococcusfaecalis, and others have been distributed by house flies within patient

wards (Graczyk et al. 2001). Many strains are acquired by house flies from patients and

some strains are resistant to antibiotics (Graczyk et al. 2001). Rady (1992) isolated

Enterobacteriaceae, Micrococcaceae, Corynebacteriaceae, Brucellaceae, and

Pseudomonodaceae from house flies trapped in hospitals. Among the aforementioned

families of bacteria, some may cause septicemia in humans (Rady et al. 1992).

Although house flies primarily transport disease agents on their wings, tarsi, and

setae, they may also spread pathogens by regurgitation and fecal deposition (Graczyk et

al. 2001). In developing countries, house flies are important vectors of Chlamydia

trachomatis, which causes blindness in humans (Graczyk et al. 2001). Flies carry C.

trachomatis on their legs and probosces, and the agent survives in the gut for 6 hours

(Graczyk et al. 2001). In laboratory studies, Helicobacterpylori was isolated from

external surfaces of house flies up to 12 hours after exposure (Gruebel et al. 1997).

However, H. pylori (responsible for gastroduodenal disease), was also isolated from gut

and excreta of house flies up to 30 hours after initial feeding by house flies (Gruebel et al.

1997). Helicobacter organisms attached to intestinal epithelial walls of house fly guts

suggested that house flies were a reservoir as well as a vector (Gruebel et al. 1997).

Other bacteria isolated from the digestive tract of house flies included Klebsiella oxytoca,

Enterobacter aul-'l ,ui ian'. Burkholderia pseudomallei, Citrobacter freundii, and









Aeromonos hydrophila (Sulaiman et al. 2000). Yersiniapseudotuberculosis survived in

the house fly digestive tract up to 36 hours after exposure (Zurek et al. 2001). House

flies may contaminate a surface with Y. pseudotuberculosis by regurgitating their crop

content (Zurek et al. 2001).

Recent studies implicate house flies as vectors of Enterohemorrhagic Escherichia

coli (EHEC) 0157:H7) which causes enteric hemorrhagic disease in humans. House flies

acquired EHEC 0157:H7 from cow dung and were capable of transmitting EHEC

0157:H7 (Iwasa et al. 1999). The EHEC 0157:H7 proliferated in mouthparts of house fly

where it may be ingested and disseminated by fecal deposition (Sasaki et al. 2000).

Ingested EHEC 0157:H7 remained inside the crop for 4 days and was detected in fecal

drops (Sasaki et al. 2000).

Biology of Musca domestic

Oviposition

House flies are holometabolous insects with distinct egg, larval, pupal, and adult

stages (West 1951, Sacca 1964). Within 1 day of becoming gravid, adult females seek

decaying organic material and animal feces for their eggs (Krafsur 1985, Hogsette 1996,

Graczyk et al. 2001). Female house flies may lay 5 to 6 batches of eggs, with each batch

containing 75 to 150 eggs (Hogsette 1996, Graczyk et al. 2001).

Larval Development and Survival

House fly larvae develop in decaying organic material, including manure, and have

three distinct larval stages (West 1951, McAlpine 1987). Larvae are milky white with a

cylindrical shape that tapers anteriorly (McAlpine 1987). The posterior ofM domestic

larvae is blunt and exhibits heavily scleritized posterior spiracles (McAlpine 1987).









Temperature of breeding sites directly affects the rate of larval development (Sacca

1964, Elvin and Krafsur 1984, Lysyk 1991b, Barnard and Geden 1993, Hogsette 1996).

Developmental time from egg to adult may range from 6 days under optimal temperature

conditions to 50 days (Barnard and Geden 1993). Haupt and Busvine (1968) reported

that lower temperatures prolonged house-fly development and enhanced larval size.

Sacca (1964) documented that 35 to 380C was an optimal temperature range for larval

development. Although higher temperature enhanced the rate of development, Barnard

and Geden (1993) found that larval survival was highest between 170C and 320C.

Moisture levels within house fly breeding sites affect their survival. Animal

manure moisture content ranging from 50 to 70% yielded significantly more flies than

drier manure (Hulley 1986, Fatchurochim et al. 1989). Fatchurochim et al. (1989)

reported a significant decline in house fly survival in manure containing less than 40% or

more than 80% moisture. In addition, Hulley (1986) observed that manure with low

moisture levels encouraged parasitism by pteromalid wasps. However, Hogsette (1996)

found that some house flies could survive in manure containing less than 5% moisture,

suggesting that house flies may survive under extreme conditions.

Survival of house fly larvae is also influenced by larval density within breeding

sites. Haupt and Busvine (1968) and Barnard et al. (1998) observed inverse relationships

between density and larval size and larval weight. Smaller larvae ultimately developed

into smaller pupae and adults (Barnard et al. 1998). Larval mortality was significantly

greater at high densities versus lower densities, while intermediate larval densities

produce more viable progeny (Haupt and Busvine 1968, Bryant 1970). Bryant (1970)

hypothesized that breeding sites conditioned by presence of larval densities regulated









oviposition rates, and thus egg densities in natural populations maintained an optimal

density.

Adult Behavior

Activity and longevity

Behavior and activity of adult house flies changes with age. As male house flies

age, wing function declined due to age and damage caused by mating attempts rendering

them flightless within 12 days (Ragland and Sohal 1973). Mating activity, like flight

activity, also declined with age.

Flight activity ofM domestic may be influenced by temperature and age. House

flies are mobile between 14 and 400C but peak flight activity occurs between 20 and

300C (Tsutsumi 1968, Luvchiev et al. 1985). Flight activity significantly decreased

above 350C and activity ceased above and below 200C, but high relative humidity

contributed to a 2- to 3-fold increase in flight activity (Tsutsumi 1968, Buchan and Sohal

1981, Luvchiev et al. 1985). Since higher temperatures induced greater house fly

activity, Buchan and Moreton (1981) observed that house fly lifespan significantly

decreased at higher temperatures. They hypothesized that higher temperatures induced a

higher metabolism, suggesting that the house fly rate of living also increased (Buchan

and Moreton 1981, Buchan and Sohal 1981). Later experiments confirmed that life

expectancy of both sexes significantly declined as temperature increased from 20 to 350C

(Fletcher et al. 1990, Lysyk 1991a).

Population density may also influence longevity of adult house flies. The life

expectancy in the lab may range between 12 and 30 days for adult male house flies and

between 11 and 44 days for adult females (Ragland and Sohal 1973, Fletcher et al. 1990).









Caged experiments using adult house flies showed an inverse relationship between adult

life expectancy and population density (Rockstein et al. 1981). Susceptibility to high

mortality associated with high density was greater for males than females (Haupt and

Busvine 1968). Field experiments using artificial garbage dumps showed exponential

growth of fly populations within 1 month of dumping the garbage and confirmed that as

density increases, survivability decreases (Imai 1984, Krafsur 1985). Both adult males

and females also showed an inverse relationship between life expectancy and mate access

(Ragland and Sohal 1973).

Dietary restrictions may also influence life expectancy and activity of adult house

flies. Rockstein et al. (1981) reported that protein-starved house flies of both sexes had a

significantly lower life expectancy than protein-satiated flies. Adding sucrose for house

flies reared on manure or powdered milk significantly increased the longevity of both

sexes (Lysyk 1991a). Starved flies and flies fed on sugar-only diets were significantly

more active than protein-satiated house flies (Tsutsumi 1968, Skovmand and Mourier

1986). Conversely, replete flies rested and showed a significantly higher frequency of

regurgitation and resting behaviors (Tsutsumi 1968).

Photoperiod

House flies are diurnal insects whose activity is directly related to light intensity

(Tsutsumi 1968, Sucharit and Tumrasvin 1981). Adult house flies entrained on a 12:12

(L:D) photoperiod showed resting behavior induced by lower light levels, and ceased

flight activity at the onset of night even when the photoperiod was removed (Tsutsumi

1968). Although peak activity times ranged from 9AM to 4PM, continuous brightness

ultimately suppressed the circadian rhythm of the house fly and complete darkness

inhibited house fly activity (Tsutsumi 1968, Meyer et al. 1978, Semakula et al. 1989).









Dispersal

House flies are disease vectors capable of dispersing between 5 and 20 miles from

their point of origin (Schoof and Silverly 1954b, Morris and Hansen 1966). Initial mark-

recapture studies showed that flies dispersed randomly and approximately 50% of

150,000 released flies were captured within 12 mile from their initial release point

(Schoof and Silverly 1954b). It was estimated that flies migrate 0.5 miles to 2.5 miles

over a period of 1-5 days (Morris and Hansen 1966). However, a lack of available

breeding sites encouraged flies to disperse up to 12 mile within 3 to 8 hours (Pickens et al.

1967). Although dispersal was random, Pickens et al. (1967) observed house flies were 2

to 3 times more likely to disperse from clean dairy farms versus unsanitary farms with

multiple breeding sites.

Environmental factors such as wind may also affect dispersal (Morris and Hansen

1966). Strong down winds may aid in dispersal, but house flies have been observed

flying upwind of breezes between 2 and 7 mph (Morris and Hansen 1966, Pickens et al.

1967).

In poultry and dairy units containing great abundance of animal manure, house flies

dispersed approximately 50 meters (Lysyk and Axtell 1986, Hogsette et al. 1993) .

Rather than density-dependent mortality in field studies, evidence shows density-

dependent dispersal toward better habitat (Imai 1984, Krafsur 1985). However, studies in

poultry houses showed house fly distribution downwind was twice as great as upwind

with dead-air zones containing the greatest abundance of adults (Geden et al. 1999).









Attractants for Musca domestic

Chemical Attractants

House flies respond to a wide variety of chemical or odorous attractants. In initial

studies, excrement and decomposing organic material attracted significant numbers of

house flies into containment traps (West 1951, Mulla et al. 1977). Food baits composed

of sugar, molasses, putrified egg extracts, or chicken and rice were also successful

attractants or served as a medium for insecticides (Pickens et al. 1973, Mulla et al. 1977,

Pickens et al. 1994, Pickens 1995). Other studies using an odorous "dumpster recipe"

caught significant numbers of house and stable flies, but such attractants may be limited

to the outdoors (Pickens et al. 1975, Rutz et al. 1988).

The discovery and synthesis of the female sex pheromone (Z)-9-tricosene led to the

development of muscalure and enhanced the efficacy of synthetic fly baits (Carlson and

Beroza 1973, Carlson et al. 1974). Although (Z)-9-tricosene is produced by females,

field trials showed significant attraction of both male and female house flies (Pickens et

al. 1975, Rutz et al. 1988, Chapman et al. 1999). High concentration of (Z)-9-tricosene

many act as an aggregation pheromone for both sexes ofM. domestic (Chapman et al.

1998).

Physical Attractants

Color

House flies respond to a variety of environmental factors such as color, light

quality, light reflectance, and color contrast (Hecht 1970). High color saturation of a

surface combined with a strong contrast between that surface and its surrounding

environment was thought to be more attractive to M domestic than individual colors,

however their response to individual colors seemed to change with temperature (Pickens









et al. 1969, Hecht 1970, Green 1984, Bellingham 1995, Snell 1998). Although Hecht

(1970) detected no significant differences in house fly response to black and white

surfaces across temperatures ranging from 15 to 400C, he also did not measure the quality

of reflected light.

The spectrum of reflected light, regardless of surface color, is more likely to induce

landing response by house flies than the color of the surface (Bellingham 1995).

Surfaces that reflected UV were more attractive to stable flies, while surfaces that

absorbed UV were more attractive to horse flies (Agee et al. 1983, Hribar et al. 1991).

Colorimetric studies with the face fly, Musca autumnalis, suggested that edge effects of

baited traps could be enhanced by maximizing color contrast between traps and the

surrounding environment (Pickens 1990).

Surfaces

Plane geometric patterns or shapes displayed on a surface may also enhance

landing-response by M. domestic. Single shapes consisting of a large area and perimeter

were significantly more attractive than a series of small shapes with small perimeters

(Bellingham 1995). When house flies were presented with a series layout of squares,

they significantly preferred outer squares and edges versus inner squares, with both sexes

exhibiting significant preference toward shape corners (Bellingham 1995). There were

no significant preferences by house flies toward symmetric versus asymmetric shapes,

but simple shapes such as triangles and rectangles were significantly more attractive to

house flies than complex shapes such as hexagons and octagons (Bellingham 1995).

Bellingham (1995) and Hecht (1970) observed that house flies preferred to rest on rough

dark surfaces such as red and black and preferred matte surfaces over glossy surfaces.









Overall, house flies preferred to rest on corners and edges of shapes or objects as well as

narrow vertical objects hanging from ceiling, but they exhibited no significant preference

toward horizontal or vertical stripes on a glue board (Keiding 1965, Bellingham 1995,

Chapman et al. 1999). Later experiments on landing response demonstrated that house

flies significantly preferred a clumped distribution of small black spots against a white

background versus a regular distribution of spots (Chapman et al. 1998, Chapman et al.

1999). These studies suggested that visual cues resembling house-fly aggregations may

also induce landing response (Chapman et al. 1999).

Light

The house fly eye is composed of different cells that are capable of gathering

information about light quantity, quality, and polarization within the surrounding

environment. Each facet of the compound eye ofM domestic contains three different

kinds of photocells designated as R1 R6, R7, and R8 (McCann and Arnett 1972). Each

cell type provides specific visual information to the insect (McCann and Arnett 1972).

Cells R1- R6 + R7 contain photopigments sensitive to 350-nm and 490-nm peaks with

R8 containing photopigment sensitive to 490 only (McCann and Arnett 1972, Bellingham

1995). The dorsal rim area of the house fly eye detects polarization and polarization

sensitivity is located in the R7 and R8 marginal cells (Philipsborn and Labhart 1990).

Philipsborn and Labhart (1990) determined that house fly attraction to polarized light,

especially in the UV range, is directly related to intensity of light. However, polarized

UV did not always elicit phototactic response from house flies (Philipsborn and Labhart

1990). Polarization sensitivity is thought to provide information on spatial forms,

motions, velocity, and contrast ratio in the fly's environment and thus may help the fly

track mates (McCann and Arnett 1972, Bellingham 1995).









The visible spectrum for M domestic ranges 310 nm 630 nm, with optimal

attraction observed at 350 nm (Thimijan and Pickens 1973, Bellingham 1995).

Electroretinogram studies have shown that the M domestic eye is sensitive to UV light

ranging from 340 nm to 370 nm and blue-green light ranging from 480 nm to 510 nm, but

there is debate over how this sensitivity affects optomotor response ofM. domstica

(Goldsmith and Fernandez 1968, McCann and Arnett 1972, Thimijan and Pickens 1973).

Goldsmith and Fernandez (1968) observed positive phototaxis by M. domestic towards

UV light of 365 nm. McCann and Arnett (1972) observed that M domestic is equally

sensitive to 350 nm UV and 480 nm blue-green and concluded the house-fly eye

contained separate photopigments for UV and blue-green light sensitivity. Similar

studies with the face fly, Musca autumnalis, revealed a similar spectral range from 350

nm to 625 nm with peak sensitivities at 360 nm and 490 nm (Agee and Patterson 1983).

Although blue-green sensitivity was relatively high, M. domestic attraction gradually

decreased from 390 nm to 630 nm with no significant differences between male and

female responses (Thimijan and Pickens 1973). Further studies have shown the house fly

eye contains more UV-sensitive pigments in its dorsal region (Bellingham 1995). It was

hypothesized that sensitivity to UV and blue green light may allow the fly to distinguish

between ground and sky and detect predators or mates against the sky (Bellingham 1995).

Green and red light wavelengths may induce negative phototaxis in M. domestic

(Green 1984). Green (1984) observed a direct relationship between attraction and

intensity of near-UV 400-nm light and an inverse relationship between attraction and

intensity of 550-nm (green) light. Straight UV elicited a significantly stronger

phototactic response from M. domestic than green-UV suggesting that green-UV is less









attractive to house flies (Green 1984). Musca domestic were unable to distinguish red

lights from green lights at various intensities (Green 1984). Bellingham (1995) observed

that house flies detected red light (630 nm) but sensitivity to red was not attraction.

Female house flies were more sensitive to red than males with the dorsal region of the

eye containing red-sensitive pigments (Bellingham 1995).

Control Using Attractants

Chemical Baits

Insecticidal food baits or containment traps rely on synthetic attractants such as

muscalure ((Z)-9-tricosene) to attract house flies and provide localized control of house

fly populations. High doses of muscalure mixed with a sugar bait attracted significant

numbers of house flies and seemed to promote significantly higher consumption of

insecticide baits (Morgan et al. 1974, Lemke et al. 1990). Newer technology

incorporating polymer beads impregnated with (Z)-9-tricosene significantly enhanced the

long-term efficacy of sugar baits (Chapman et al. 1998). Physical traps combining

muscalure with visual cues caught significantly more house flies than traps without

muscalure (Mitchell et al. 1975, Mulla et al. 1979). However, baited trap catch decreased

significantly at lower temperatures due to decreased volatilization of attractants (Pickens

and Miller 1987).

Physical Traps

Baited jug traps made from plastic milk jugs, utilized (Z)-9-tricosene and indole to

capture house flies breeding in poultry units (Burg and Axtell 1984). Although this

design killed thousands of house flies, jug traps are primarily used for monitoring house

fly populations (Burg and Axtell 1984, Stafford III et al. 1988).









Pickens and Miller (1987) reported that pyramid traps, utilizing glue boards or

electric grids, were effective at intercepting dispersing house flies before they entered

buildings (Pickens and Miller 1987). Subsequent trials with pyramid traps determined

that vertical orientation of electric grids combined with chrome plating on electronic

grids attracted and killed significantly more house flies (Pickens and Mills 1993).

Replacing paint with white plastic increased UV reflectance, and thus attracted

significantly more house flies toward pyramid traps (Pickens and Mills 1993).

Success of physical traps is largely dependent on their proximity to house fly

breeding sites. Baited jug traps were most effective when hung 1 m above breeding and

aggregation sites (Burg and Axtell 1984). Pyramid and baited traps were significantly

more effective when placed within 3 m of breeding sites or sheltered from wind (Pickens

and Miller 1987).

Insect Light Traps (ILT)

Insect light traps (ILTs) and electronic fly killers (EFKs) utilize UV light to lure M.

domestic onto glue boards or kill them with electricity. Such devices are designed to

exploit positive phototaxis in house flies and remove them from environments where

insecticide applications are not an option. However, house fly response to UV traps

varies due to a range of environmental and physiological factors.

House Fly Response to ILTs

Age ofM domestic may influence their response to light traps. Adult male and

female house flies aged 7 d or older exhibited significantly slower response to UV light

traps than flies aged 1 to 5 days (Pickens et al. 1969, Skovmand and Mourier 1986).

Deimel and Kral (1992) observed that light sensitivity was related to age-dependent

concentration of the photopigment xanthopsin in cells R1-R6. Age-dependent sensitivity









to light may have been influenced by visual experience gained within the first five days

after adult emergence (Deimel and Kral 1992).

Hunger and nutrition also influenced searching activity ofM. domestic, and thus

light-trap catch may also be affected (Skovmand and Mourier 1986). House flies that

were starved or sustained on a sugar and water diet were significantly more active than

protein-satiated flies and thus starved flies responded to UV-light traps in significantly

less time than protein-satiated flies (Skovmand and Mourier 1986). Bellingham (1995)

suggested that food searching is non-oriented behavior motivated by the insect's intrinsic

nutritional needs. Once the insect satiates its hunger, then its behavior shifts toward mate

location and environmental orientation (Bellingham 1995). This reasoning suggests that

starved house flies are not necessarily more attracted to UV-light traps than satiated flies,

but rather they have a higher probability of being caught simply because they are more

active.

Design and Location of ILTs

Further attempts to enhance ILT performance focused on trap designs included

increasing bulb wattage, manipulating trap colors, and adding reflective surfaces to the

trap exterior. Increased bulb wattage provided a higher intensity of UV light, and thus

yielded a significant increase in catch, but the use of black light blue (BLB) bulbs did not

significantly increase attraction of house or stable flies when compared to standard black

light (BL) bulbs (Pickens 1989b, Snell 1998). Pickens and Thimijan (1986) suggested a

black-box trap offered greatest contrast to UV bulbs and caught significantly more flies.

However, Snell (1998) found that black background was significantly less attractive than

white background. Snell (1998) also suggested that grills created a significant distraction

for house flies by providing them with a place to rest. Traps with greater grill lengths in









front of the UV bulbs caught significantly fewer flies compared with traps that had lower

grill length (Snell 1998).

Location of light traps also plays an important role in their efficacy. Studies with

electronic fly killers (EFKs) in poultry units demonstrated that traps located within Im of

the ground eliminated significantly more house flies than traps located 2m or higher

(Driggers 1971). Subsequent studies with baited pheromone traps also reinforced the

idea that ground-level traps within 3m of breeding sites were most efficient for

eliminating flies (Mitchell et al. 1975, Pickens and Miller 1987). Skovmand and Mourier

(1986) acknowledged that competing light sources as well as competing attractants

distracted a significant number of house flies away from EFKs. They concluded UV-

light traps, specifically EFKs, only provided marginal control in swine units because the

abundance and production of house flies exceeded the traps' ability to recruit flies

(Skovmand and Mourier 1986).

Competing Light Sources

The urban environment presents house flies with location challenges as well as

artificial light sources that may interfere with UV light traps. Lillie and Goddard (1987)

demonstrated that multiple light traps significantly reduced house fly populations in

restaurant kitchens. However, traps visible to the outdoors may attract flies into the

structure (Lillie and Goddard 1987). Additionally, placement of light traps in dim areas

enhanced the catch of house flies (Pickens and Thimijan 1986). Both Pickens and

Thimijan (1986) and Shields (1989) implied that artificial cool-white fluorescent light

adversely affected house-fly attraction to UV light traps, but neither study examined

intensity or quality of artificial light.









Although greater light intensity may attract more flies, other factors such as flicker

fusion and directionality of light may influence house fly response to a light source.

Syms and Goodman (1987) discovered that light flicker created by alternating current

(AC) was more attractive to house flies than light produced by direct current (DC). Ultra

violet lights from AC sources with half the intensity of DC sources caught significantly

more house flies (Syms and Goodman 1987, Shields 1989). Additionally, diffuse sources

of light were significantly more attractive to M domestic than directional light (Roberts

et al. 1992). Neither Syms and Goodman (1987) nor Roberts et al. (1992) found any sex-

related differences in house-fly response to AC-flicker or diffuse light sources.

The effects of competing light sources on vector monitoring programs utilizing

light traps have been documented in the mosquito literature. Bowden (1973)

acknowledged the inverse relationship between mosquito catch in light traps and intensity

of background illumination from the moon. The intensity of moonlight gradually

changed with each phase, light trap catches of mosquitoes adjusted accordingly (Bowden

1973). In Venezuela, illumination from a full moon reduced light trap catch abundance

of Anopheles spp. by approximately one-half when compared to moonless trap nights

(Rubio-Palis 1992). Similarly in India, Singh et al. (1996) documented significant

reduction of Anopheles spp. caught by Center for Disease Control (CDC) light traps

during a full moon phase compared with moonless trap nights. Although total catch was

significantly lower, the parity rates ofAnopheles spp. among samples remained the same

regardless of the moon phase (Rubio-Palis 1992, Singh et al. 1996).

Bowden (1973) documented an inverse relationship between moonlight and trap

catch for a variety of species of Coleoptera and Lepidoptera. Since light intensity









decreases at a rate equal to the inverse square of distance from its source, Bowden (1973)

asserted that light traps exerted a region of influence unique to individual species and that

insects outside of this region of influence would remain unaffected by the light trap.

Therefore, modifications to light trap output or the intensity of competing illumination

would alter a light trap's area of influence (Bowden and Church 1973, Bowden 1982). In

subsequent studies, Bowden (1982) estimated a minimum 12:1 ratio of background

luminosity to trap luminosity was necessary to have an adverse effect on light trap

performance. Increasing UV output from light traps may overcome some of these

obstacles, but Bowden (1982) also noted a curvilinear relationship between total UV

output and trap catch where significant increases in UV output resulted in marginal or no

increases in trap catch (Bowden 1982). It is not known if the same relationship exists for

house flies.

Statement of Purpose

The purpose of my research is to understand how factors in urban environments

affect the catch efficacy of UV light traps used to manage house flies. I have designed a

light-tunnel bioassay that presents house flies with both a UV light trap and a source of

overhead competing light. Since location of UV traps may influence catch, the first

research chapter (Chapter 2) establishes a baseline study of a light-tunnel bioassay that

does not exhibit location bias. This bioassay was then used to determine effects of house

fly age and gender on trap catch. The time to catch 50% of a population (CT5o) was

estimated for house flies to determine the approximate time house flies responded to a

UV trap. Information from these studies helped to eliminate any bias and determine the

proper age range of house flies and length of time for the experiments.









Chapter 3 explores how intensity and spectrum of competing light sources affects

house fly response to UV light traps. Light intensities sampled in five local restaurants

and grocery stores provided a baseline range of intensity treatments for my experiments.

For light quality experiments, house flies were presented with competing lights with

spectral outputs ranging from UV light up through warm-white fluorescent.

Finally, Chapter 4 explores whether continuous exposure to artificial light induces

habituation or attraction. If house flies habituate to light after continuous exposure, then I

hypothesize that they would be less attracted to that source of light over time.














CHAPTER 2
ESTIMATES OF RESPONSE TIME BY HOUSE FLIES TOWARD UV LIGHT
TRAPS USING LIGHT-TUNNEL BIOASSAY

Introduction

The house fly, Musca domestic L., is a synanthropic filth fly that breeds in

garbage and animal waste (Schoof and Silverly 1954a, Greenberg 1973, Imai 1984,

Graczyk et al. 2001). Larvae develop in manure, and the adults will feed on the larval

substrate (Hogsette 1995). Growing populations of adult house flies are a nuisance to

livestock, poultry, and humans, especially in urban centers adjacent to farming

communities (Hogsette and Farkas 2000). In addition, house flies may also transmit

enteric pathogens such as .\l/ge//l spp. and Salmonella spp., which they may acquire

from their breeding sites and transmit to humans (Levine and Levine 1991, Graczyk et al.

2001)

The significance of house flies as disease vectors is enhanced by their capability of

dispersing approximately 30 km from their point of origin (Schoof and Silverly 1954b,

Morris and Hansen 1966). Subsequent studies estimated that flies dispersed an average

of 1 to 4 km over a period of 1 to 5 d in search of suitable breeding sites within rural or

urban areas (Morris and Hansen 1966, Hogsette and Farkas 2000).

As house flies cause problems in structures, light traps were developed as a tool to

intercept house flies by attracting them to UV light and killing them with glue boards or

high-voltage electricity (Pickens et al. 1969, Bowden 1982, Roberts et al. 1992). Prompt

removal of house flies within hospitals, grocery stores, or restaurants is necessary to









prevent transmission of diseases among people and food sources (Levine and Levine

1991, Rady et al. 1992, Graczyk et al. 2001).

Insect light traps are used to attract and catch house flies, but factors such as fly

age or trap location within a building may limit trap catch. Dispersal from breeding sites

into structures may take days, and as flies disperse, they age and may exhibit a significant

decline in flight activity (Ragland and Sohal 1973). As house flies enter structures, light

traps obscured from view may have little or no effect on a house-fly infestation and

significant wind or air movement within a building may redirect house flies downwind

away from potential light traps (Lillie and Goddard 1987, Rutz et al. 1988, Geden et al.

1999). Additionally, incident light from windows or overhead fixtures may also be an

additional source of variability for light trap studies (Pickens and Thimijan 1986, Syms

and Goodman 1987).

Although previous studies sought to understand variables that may affect light-trap

performance, none have provided a standardized bioassay that eliminates variables such

as background light, trap location, or air movement within a structure. Therefore, the

first objective of this study was to develop and standardize a procedure that overcomes

effects associated with light-trap placement. The second objective was to use the

standardized procedure to examine the effects of fly age on light-trap catch efficacy and

to examine house fly response time to insect light traps.

Materials and Methods

Insects. Two strains ofM. domestic were used in this research; the USDA-

CMAVE strain and the Horse-Teaching-Unit (HTU) strain, both from Gainesville, FL.

Larvae from USDA-CMAVE strain were reared on USDA larval medium and held on a

12:12 (L: D) photoperiod (Hogsette 1992). Larvae from the HTU strain were reared on a









medium containing 3 liters wheat bran, 1.5 liters water, and 250 ml of Calf Manna

(Manna Pro Corp., St. Louis, MO) pellets. All stages of HTU strain were placed on a

12:12 (L: D) photoperiod at 26 1IC and 51.03 3.49% RH. Adult flies from both

strains were provided granulated sugar, powdered milk, and water ad libitum and held on

a 12:12 photoperiod (L:D) (Hogsette et al. 2002). Adult flies were held no longer than 7

days.

Before experimentation, adult flies between 2 and 5 d of age were aspirated from

screen cages (25.4 by 53.3 by 26.7 cm) using a handheld vacuum with modified crevice

tool. Aspirated flies were transferred into a refrigerator (-50C) for 2 min to subdue

activity. Flies were removed from the refrigerator and placed on a chilled aluminum tray,

counted and sexed. Counted and sexed flies were placed into plastic cups (237 ml), lids

were placed over the cups, then the flies were held at room temperature for

approximately 30 min before being placed into experiments. All flies were handled with

camel hair paint brushes and featherweight forceps.

Light tunnel design. The enclosed light-tunnel (152 by 20 dia. cm metal duct)

consisted of a release cage attached to a galvanized aluminum light tunnel that terminated

in a box enclosing a light trap (Fig. 2-1). The release cage (30 by 30 by 45 cm) was fitted

with a sheet-metal bottom and aluminum window screen on the top, sides, and one end.

Stockinette was fitted on the remaining end (30 by 30 cm) to allow access into the cage.

Release cages were placed on a 10.4 cm-high platform to make them level with a light

tunnel entrance. The light tunnel (152 by 20 dia. cm metal duct) was painted with one

coat of primer and one coat of flat black paint, then allowed to cure for at least 3 d to

eliminate paint fumes. A light-tunnel entrance (20 cm dia.) was cut into the box









enclosure (66 by 91 by 60 cm) which was constructed of corrugated cardboard. The 20

cm hole was centered horizontally on the 91-cm face and was 12.7 cm from ground level.

Vents were cut in the top of the box enclosure (17.7 by 38.1 cm) to prevent buildup of

heat from light traps. A piece of black organdy was glued over each vent to prevent flies

from escaping. A piece of plywood (91 by 60 cm) was painted with white paint and

placed inside the box enclosure opposite the light tunnel entrance. One UV light trap

(Nova, Whitmire Microgen Inc., St. Louis, MO) was mounted with four screws onto the

white plywood inside the box enclosure. The trap was laterally centered and located

directly opposite the light tunnel entrance. The trap utilized three 15-watt UV bulbs

(Sylvania QuantumTM, Manchester, UK) as well as a horizontal (7.6 by 40.6 cm) and a

vertical glue board (25.4 by 40.6 cm). Ultra-violet (UV) bulbs in traps had < 1000 h use.

A workshop fixture containing two 40-watt Sylvania cool-white fluorescent light bulbs

was hung 8 cm above top of release cages to provide a source of background light that is

common in urban environments. The distance of 8 cm above the cages was selected in

order to establish intensity comparable with levels of competing light in urban

environments.

Procedure. To perform an experiment, new glue boards were placed inside traps

and all lights were turned on. One hundred sexed flies were released from a plastic cup

(237 ml) into a release cage. Experiments commenced when stockinette on the release

cages was unfurled and wrapped around the entrance of the light tunnel, allowing flies

access to the UV light trap. At the end of each experiment, the release cages were sealed

and removed, traps turned off, and glue boards collected. Flies not captured were









removed from the experimental set up prior to subsequent repetitions. Ambient

temperature for all experiments was approximately 290C.

Quality and quantity of background light and ultraviolet light were measured at the

release-cage end of the light tunnel with a USB2000 Spectrometer (Ocean Optics,

Dunedin, FL) (Fig.2-2). Absolute light quantity from cool-white fluorescent light and

UV-trap output was measured with a HOBO Light Intensity logger (Onset, Bourne,

MA).

Intensity data from light traps and overhead fluorescent light were analyzed at each

position to investigate significant differences among the light sources. Separate one-way

analyses of variance were run using light intensity as the response variable against trap

and position within building as main factors.

Location dependent assay. Experiments were conducted in two buildings (3 by 3

m) designated as Buildings A and B. All windows were covered with aluminum foil to

prevent external light from interfering with experiments. Two positions were identified

within each building and designated as positions al and a2 for Building A and positions

b and b2 for Building B. The four box enclosures opposite the release cages were

consecutively numbered and rotated among all four possible positions nested within the

two buildings. All repetitions used house flies from both strains. Four replications, each

with 100 adult house flies (50 M: 50 F) aged 2 to 5 d, were conducted per box and

position, for a total of eight replications per building. Assays were concluded after 4 h.

Age dependent assay. Pupae from both strains were removed from larval medium

and placed in separate screen cages (40.6 by 26.7 by 26.7 cm). Flies were allowed to

emerge for 24 h, then pupae were removed to ensure that all flies were of the same age.









Age of flies was based on the number of days after adult emergence from pupal cases.

The assay was conducted with 100 flies (50 M: 50 F) aged 1, 3, 5, or 7 d placed in the

release cage and left for 4 h. Flies on glue boards were counted sexed. Four replications

per age were conducted.

Time dependent assay. Time treatments were started simultaneously when 100

adult flies (50 M: 50 F) were placed into each of four separate release cages for 1, 2, 4, or

8 h. Treatments were randomly assigned to each release cage apriori with four

replications per time. At the end of each time period, the assigned release cage was

closed, glue boards were collected, and the light trap was turned off.

Statistical analysis. For location studies, total numbers of male and female flies

caught on glue boards were analyzed using a two-way nested analysis of variance with

box enclosure and building as fixed factors with position nested within the building.

Time and age studies were separately analyzed with one-way analysis of variance with

time (h) or age (d) as fixed factors. Means separation for significant F-values was

performed with a Student-Newman Keuls (SNK) test. A catch time for 50, 90, and 95%

of house flies (CT5o) caught by UV light traps was estimated using probit analysis (SAS

2001).

Results and Discussion

Location Dependent Assay. Analyses of spectrometry data indicated there were

no significant differences in light spectra and intensity from UV light traps (F=0.29; df=

3, 298; P = 0.83) or overhead cool-white fluorescent light among the four set ups

(F=2.22; df = 3, 325; P = 0.085) (Figures 2-2 and 2-3). There were no significant

differences in the numbers of house flies caught among the locations within buildings A

and B (F = 0.89; df = 3, 13; P = 0.46) nor were any significant differences detected









among the four box enclosures (F=0.22; df = 3, 13; P = 0.87) (Table 2-1). On average,

65 adult house flies were caught among all positions over a period of 4 h, thus the

different positions within and among buildings A and B did not significantly influence

house fly response to light traps (Table 2-1).

In previous studies, the effects of location bias on catch efficacy of UV light traps

depend largely on environmental factors unique to each site. Lillie and Goddard (1987)

found that catch efficacy in urban environments varied due to trap location relative to

other sources of light such as windows or doors that might lure flies away from a UV

light trap. Light quality and intensity were standardized in this research among all

positions within our buildings. Rutz et al. (1988) suggested that UV light traps are most

effective when placed in close proximity to house-fly breeding sites and areas of high

activity, but they did not define any specific distance. In the current study, house flies

were released 2.66 m from the UV light traps. Furthermore, Geden et al. (1999) reported

that in closed poultry units, house flies significantly preferred dead-air spaces versus

direct air currents. By providing an enclosed light-tunnel design, the current study

eliminated air movement between the release cage and the light trap. Thus, results

showed that removing variability of location, trap distance, background light intensity,

and air movement, assured that the house flies responded to light traps in consistent

manner.

Age-dependent assay. Significantly greater numbers of male house flies aged 1, 3,

and 5 d were caught by UV light traps than 7-day old male house flies (Table 2-2). One

possible reason for this decline is that as male house flies age, wing function declined due

to damage caused by mating attempts (Ragland and Sohal 1973). Within our colonies, I









observed mating attempts among flies of all ages but noticed significant wing damage

among males aged 7 d or older.

There was no significant difference in response among all age groups of female

house flies toward UV light traps (Table 2-2). The nutritional state of 7 d old female

house flies may have influenced their activity levels. All house flies had access to protein

(powdered milk), carbohydrates (granulated sugar), and water within 1 h prior to

experiments. Tsutsumi (1968) reported that protein-satiated house flies rest more and fly

less than protein-starved house flies. However, if protein-satiated adult females were

mated, then their flight activity may have increased as they searched for a site for

oviposition (Tsutsumi 1968, Skovmand and Mourier 1986). If females were gravid and

looking for a dark place to oviposit, then one would expect to see a decline in their

response towards light traps.

When results of both sexes were combined, the overall response to UV light traps

by adult house flies significantly decreased at 7 d of age because of the reduction in the

number of males captured (Table 2-2). Results agree with previous studies indicating

that significantly fewer house flies aged > 5 d were caught in UV light traps (Pickens et

al. 1969). As house flies age, their sensitivity to light decreases due to deterioration of

photopigments within cells R1-R6 of the fly eye (Deimel and Kral 1992). These results

confirmed that house flies aged 5 5 d are most likely to be caught in UV light traps.

Time-dependent assay. The cumulative mean number of male and female house

flies caught by UV light traps significantly increased over a time period of 1 to 8 h (Table

2-3). Although total trap catch by 8 h was significantly greater than catch at 4, 2, or 1 h,









some house flies did not respond to the light trap and remained in the release cage

throughout the duration of the experiment (Table 2-3).

Male house flies were caught inside the light traps within an estimated CT50 of 1.56

h (99 min) (Table 2-4). The CT90 and CT95 estimated catch time for males at 5.03 h

(301.8 min) and 7.01 h (420.6 min), respectively (Table 2-4). Female house flies were

caught inside the light traps within an estimated CT50 of 1.90 h (114 min) (Table 2-4).

The CT90 and CT95 estimated catch time for females at 7.02 h (421.2 min) and 10.17 h

(610.2 min) respectively (Table 2-4).

Probit analysis estimated the CT50 for total house fly response toward an UV light

trap at approximately 1.72 h (103.2 min) (Table 2-4). The CT90 and CT95 estimate for

total house fly catch was 6.01 h (360.6 min) and 8.57 h (514.2 min), respectively (Table

2-4). There was no significant difference between male and female response time as

evident by overlapping 95% confidence intervals for CT50, CT90, and CT95 (Table 2-4).

Skovmand and Mourier (1986), who also conducted a series of light-trap

experiments inside an enclosed chamber, concluded that male house flies responded to

UV light traps in significantly less time than females. The CT50 estimate of 99 min (1.56

h) for male response was similar to their estimated LT50 of 100 min (Skovmand and

Mourier 1986). However, the CT50 estimates for females of 114 min was slower than the

52 min reported by Skovmand and Mourier (1986), and there were no significant

differences in response time between males and females (Table 2-4). During these

studies, I observed some house flies remained inside the release cage throughout the

duration of the test and thus, reduced our estimates for house fly response to light traps.






29


In conclusion, the light-tunnel bioassay enabled us to standardize conditions for age

and time studies by reducing variability associated with air movement, trap location, trap

distance, and background light. House flies that were < 5 d old exhibited significantly

greater attraction toward UV light traps than older flies. Estimates of CT50 by house flies

toward UV traps ranged from 99 to 114 min for males and females, respectively, with no

significant difference in response between the sexes.












Table 2-1. Effect of building, position within building, and box enclosure on the number of house flies caught in UV light traps (50
M: 50 F per repetition).

Building Mean SE Position Mean SE Box enclosure Mean SE

A 63.56 2.41 al 63.75 3.79 1 65.62 3.56
B 68.00 + 2.58 a2 64.87 + 3.63 2 65.62 + 3.71
bl 68.37 3.72 3 68.00 3.51
b2 68.12 3.71 4 65.87 4.25

Means within a column followed by the same letter are not significantly different (P = 0.05, Student Newman-Keuls test [SAS
Institute, 2001]).












Table 2-2. Influence of age and sex on number of house flies caught in UV light traps (50 M: 50 F per repetition)

Fly age (d)
1 3 5 7
Gender Mean SE Mean SE Mean SE Mean SE

Male 40.75 + 2.33a 38.25 + 1.47a 45.5 1.97a 22.75 + 3.22b
Female 46.25 2.18a 48.25 3.75a 42.5 + 2.52a 40.00 + 1.08a
Total 87.0 + 3.21a 87.25 3.37a 88.0 + 2.67a 62.6 + 4.21b

Means within a row followed by the same letter are not significantly different (P = 0.05, Student Newman-Keuls test [SAS Institute,
2001]).












Table 2-3. Cumulative house-fly catch in UV light traps over time (50 M: 50 F per repetition)

Time (h)
1 2 4 8
Gender Mean SE Mean SE Mean SE Mean SE

Male 15.2+ 1.88a 31.0+ 1.92b 37.0 2.24b 48.0+ 1.3c
Female 12.6 1.03a 26.8 3.76b 32.8 3.92c 45.8 1.46d
Total 27.8 2.6a 57.8 5.32b 71.8 6.58c 93.8 2.03d

Means within a row followed by the same letter are not significantly different (P = 0.05, Student Newman-Keuls test [SAS Institute,
2001]).












Table 2-4. Estimated time (h) to catch of adult house flies by UV light traps using Probit analysis

n Reps Slope + SE CT50 95% C. I. CT90 95% C. I. CT95 95% C. I. X2 P

Male 50 5 2.52 0.18 1.56 1.40-1.72 5.03 4.29-6.15 7.01 5.78-9.01 0.34 0.557
Female 50 5 2.26 0.15 1.90 1.71-2.11 7.02 5.88-8.80 10.17 8.19-13.43 0.52 0.467
Total 100 5 2.35 + 0.11 1.72 0.59-1.84 6.01 5.31-6.95 8.57 7.37-10.26 1.03 0.307































Figure 2-1. Light tunnel design illustrating release cage (30 by 30 by 45 cm)
(foreground), overhead light source (101.6 cm), light tunnel (152 by 20 cm),
and box enclosure (66 by 91 by 60 cm) containing light trap













Intensity + SE of UV light traps
1.33 + 0.048 lumens/m2


Intensity (lumens / m2) of UV-light trap with relative intensity of light by
wavelength


kIterity (coLts)


20M 3W0 4W 6W0 6om 70
WMMethergh ()


Figure 2-2.












Intensity SE of cool white
fluorescent light
54.87 + 0.92 lumens/m2


200 300 400 500 600 700 800
Wameqlh(rrn)


Figure 2-3. Intensity (lumens/m2)
of light by wavelength


of cool-white fluorescent light with relative intensity


Wtmity (omuft)
4000-



3000-



2000-



1000a














CHAPTER 3
INFLUENCES OF QUALITY AND INTENSITY OF BACKGROUND LIGHT ON
HOUSE FLY RESPONSE TO LIGHT TRAPS

Introduction

Musca domestic L. is a synanthropic insect that breeds in animal waste,

dumpsters, and garbage (Morris and Hansen 1966, Imai 1984). They are known to

transmit pathogens such as Salmonella spp., .,/ngel// spp., Campylobacter spp., and

enterohemorrhagic E. coli from their breeding sites to open food markets, hospitals,

slaughter houses, and animal farms (Levine and Levine 1991, Iwasa et al. 1999, Graczyk

et al. 2001). Because house flies are potential disease vectors, their control in urban

environments is necessary to prevent food contamination.

A variety of devices have been developed to attract and kill house flies in

agricultural and urban areas. Baited traps containing molasses, sugar, decomposing

biomass, or animal excrement have been used to lure house flies into a catch basin from

which they can not escape (West 1951, Pickens et al. 1973, Mulla et al. 1977). Pyramid

traps utilizing glue boards or electrocution grids were effective at intercepting house flies

before they entered buildings (Pickens and Miller 1987). But although these traps may

be effective in outdoor settings, their odorous baits and visibility prohibit their use

indoors. Additionally, trapped flies must be emptied and baits must be replenished to

maintain trap efficacy.

Insect light traps utilizing ultraviolet (UV) light ranging from 340-370 nm were

developed after physiological and behavior studies demonstrated that house flies









exhibited positive phototaxis toward UV-emitting light sources (Goldsmith and

Fernandez 1968, McCann and Arnett 1972). Light traps utilizing glue boards to subdue

attracted flies are a common management tool in indoor settings (Lillie and Goddard

1987).

Ultraviolet light traps for indoor use are an alternative to chemicals, but some

factors in urban environments that may limit trap success. As house flies disperse within

a building, they may encounter competing sources of light originating from windows or

overhead light fixtures which may interfere with trap catch (Pickens and Thimijan 1986).

Previous studies demonstrated that increasing UV output of light traps significantly

enhanced catch efficacy of house flies, but they did not take into account light-trap

performance relative to competing light sources in the urban environment (Pickens and

Thimijan 1986, Snell 1998). Therefore, the first objective of this study was to examine

competing light intensities in public settings where light traps would most likely be used,

then corroborate those data with light-intensity levels in experiments to measure effects

of competing light intensity on house-fly response to UV light traps. The second

objective was to present house flies with competing light sources with different spectral

outputs and quantify their response to UV light traps.

Materials and Methods

Insects. The Horse-Teaching-Unit (HTU) strain ofM. domestic from Gainesville,

FL, was used in this research. Larvae from the HTU strain were reared on a medium

containing 3 liters wheat bran, 1.5 liters water, and 250 ml of Calf Manna (Manna Pro

Corp., St. Louis, MO) pellets. All stages of HTU strain were placed on a 12:12 (L: D)

photoperiod at 26 1IC and 51.03 3.49% RH. Adult flies from both strains were









provided granulated sugar, powdered milk, and water ad libitum and held on a 12:12

photoperiod (L:D) (Hogsette et al. 2002). Adult flies were held no longer than 7 days.

Before experimentation, adult flies were aspirated from screen cages (25.4 by 53.3

by 26.7 cm) using a handheld vacuum with modified crevice tool. Aspirated flies were

transferred into a refrigerator (-50C) for 2 min to subdue activity. Flies were removed

from the refrigerator and placed on a chilled aluminum tray, counted and sexed. Counted

and sexed flies were placed into plastic cups (237 ml), clear plastic lids were placed over

the cups, then the flies were held at room temperature for approximately 30 min before

being placed into experiments. All flies were handled with camel hair paint brushes and

featherweight forceps.

Light tunnel design. Enclosed light-tunnel design consists of a release cage

attached to a galvanized aluminum light tunnel that terminates in a box enclosing a light

trap (Fig. 2-1). The release cage (30 by 30 by 45 cm) was fitted with a sheet-metal

bottom and aluminum window screen on the top, sides, and one end. Stockinette was

fitted on the remaining end (30 by 30 cm) to allow access into the cage. Release cages

were placed on a 10.4 cm-high platform to make them level with a light tunnel entrance.

The light tunnel (152 by 20 dia. cm metal duct) was painted with one coat of primer and

one coat of flat black paint, then allowed to cure for at least 3 d to eliminate paint fumes.

A light-tunnel entrance (20 cm dia.) was cut into the box enclosure (66 by 91 by 60 cm)

that was constructed of corrugated cardboard. The 20 cm hole was centered horizontally

on the 91-cm face, and was 12.7 cm from ground level. Vents were cut in the top of the

box enclosure (17.7 by 38.1 cm) to prevent buildup of heat from light traps. A piece of

black organdy was glued over each vent to prevent flies from escaping. A piece of









plywood (91 by 60 cm) was painted with white paint and placed inside the box enclosure

opposite the light tunnel entrance. One UV light trap (Nova, Whitmire Microgen Inc.,

St. Louis, MO) was mounted with four screws onto the white plywood inside the box

enclosure. The trap was laterally centered and located directly opposite the light tunnel

entrance. The trap utilized three 15-watt UV bulbs (Sylvania QuantumTM, Manchester,

UK) as well as a horizontal (7.6 by 40.6 cm) and a vertical glue board (25.4 by 40.6 cm).

Ultra-violet (UV) bulbs in traps had < 1000 h use. A workshop fixture containing two

40-watt Sylvania cool-white fluorescent light bulbs was hung 8 cm above release cages

to provide a source of background light that is a common light source in urban

environments. The distance of 8 cm above the cages was selected in order to establish

intensity comparable with levels of competing light in urban environments.

Procedure. To perform an experiment, new glue boards were placed inside traps

and all lights were turned on. One hundred sexed flies were released from a plastic cup

(237 ml) into a release cage. Experiments commenced when stockinette on the release

cages was unfurled and wrapped around the entrance of the light tunnel, allowing flies

access to the UV light trap. After 4 h, experiments were shut down and at the end of each

experiment, the release cages were sealed and removed, traps were turned off, and glue

boards were collected. The time period of 4 h was selected because preliminary results

showed between 90 and 100% of flies within dark controls were caught inside UV light

traps after 4 h. Flies not captured were removed from the experimental set up prior to

subsequent repetitions. Ambient temperature for all experiments was approximately 27

to 290C. All repetitions contained 100 adult house flies (50 M: 50 F) between 2 and 5 d

of age.









Light intensity survey of restaurants and grocery stores. A HOBO Light

Intensity logger (Onset', Bourne, MA) was used to measure light intensity inside five

restaurants and/or grocery stores. The logger was held 1.3 m from the ground with its

light sensor facing the ceiling and the researcher carried the logger throughout the

establishment in this fashion. Data were collected at 5-s intervals until a minimum of 100

points were collected at each establishment. Direct sunlight was avoided at all locations

because its high intensity may influence average measurements of artificial light.

Impact of competing light intensity on trap catch. Four intensity levels of

competing light were set up based upon the results of the field survey. Two workshop

light fixtures, each containing two fluorescent 40-watt light bulbs, were suspended

directly above the release cages. A range of 1 to 4 40-watt bulbs were illuminated and

provided light intensities ranging from 27 to 125 lumens/m2. Three replications were

conducted per intensity level.

Impact of competing light spectra on trap catch. Four types of fluorescent light

bulbs were presented to house flies as a source of overhead competing light. The bulb

models and types were as follows: Sylvania Warm White (F40T12/WW), Sylvania

Cool White (F40T12/CW), Sylvania Daylight (F40T12/DX), and Sylvania Blacklight

(F40T12/350BL). Two fluorescent workshop light fixtures, each capable of holding two

40-watt light bulbs, were suspended directly above the release cages. Three 40-watt

bulbs of each model were placed inside the fixtures and illuminated during experiments.

Four replications were conducted per treatment.

Spectral analyses and relative intensity of all treatments were measured using a

USB2000 spectrometer (Ocean Optics, Dunedin, FL). Light intensity for all treatment









outputs was measured with a HOBO Light Intensity logger (Onset', Bourne, MA).

Since measurements of light intensity by HOBO Light Intensity logger (350 to 700 nm)

represented a proportion of total spectrum measured by the USB2000 spectrometer (200

to 820 nm), total light intensity was estimated using the following formulae where X Total

spectrum units represents relative light intensity measured by the USB2000 spectrometer and

Y Measured light units represents relative light intensity perceived by the HOBO Light

Intensity logger. Measured light represents the light intensity (lumens/m2) recorded by

the HOBO Light Intensity logger and units measured represent intensity counts per

nanometer tabulated by USB2000 spectrometer using OOIBase32 software (Ocean

Optics, Dunedin, FL).

Y Measured light units

Y Total spectrum units = Proportion Total light output (%)

Measured light (lumens/m2)

Proportion Total light output (%) = Estimate Total light output (lumens/m2)

Once the Estimate Total light output (lumens/m2) was calculated, the intensity levels of

UV (350 to 370 nm) and blue-green light (480 to 510 nm) were also calculated. The X uv

light units and s Blue-green light units represent intensity counts per nanometer tabulated by

USB2000 spectrometer using OOIBase32 software (Ocean Optics, Dunedin, FL).

Y UV light units

Y Total spectrum units = Proportion UV light output (%)

Proportion UV light output (%) Estimate Total light output (lumens/m2)

= Estimate uv light output (lumens/m2)

X Blue-green light units









Y Total spectrum units = Proportion Blue-green light output (%)

Proportion Total light output (%) Estimate Total light output (lumens/m2)

= Estimate Blue-green light output (lumens/m2)

Statistical analysis. Because all four treatments for the light-intensity experiments

and light-quality experiments could not be conducted simultaneously, both experiments

were set up using a two-way balanced incomplete block design. Treatment pairs were

randomly assigned apriori for each trial day until all possible treatment combinations

were met (SAS 2001). A dark control was run concurrently with each experiment. For

each dark control, house flies were placed into a release cage and presented with an

illuminated Whitmire Nova trap at the end of the light tunnel without a competing light

source placed overhead. Means were separated with a Student Newman-Keuls test.

Regression analysis was conducted on data from light-intensity experiments to examine

the relationship between trap catch and intensity of blue-green light. Another regression

analysis was conducted on light-quality experiments to examine the relationship between

trap catch and UV intensity.

Results and Discussion

Light intensity survey. Results of light-intensity survey at area restaurants and

grocery stores showed intensity of artificial and natural light sources ranged from

approximately 27 to 91 lumens/m2 (Table 3-1). Light intensity of treatments within

laboratory bioassays was within the range of field results (Table 3-2).

Impact of competing light intensity on trap catch. The number of males caught

in UV traps significantly decreased when intensity of the competing light exceeded 91.46

lumens/m2 when compared with dark controls (F= 9.63; df = 4, 50; P < 0.0001) (Table 3-

3). The number of females caught declined significantly when intensity of competing









light exceeded 51.43 lumens/m2 (F= 18.17; df = 4, 50; P < 0.0001) (Table 3-3). When

the data were combined, the overall results showed total catch in UV light traps

decreased significantly as the intensity of competing light source increased (F = 39.46; df

= 4, 50; P < 0.0001) (Table 3-3).

As overall competing light intensity was increased, spectral analyses showed the

relative intensity of a blue-green light increased 5x from the lowest to highest treatment

(Table 3-4; Figs. 3-1 to 3-4). Regression analysis showed a significant correlation

between increases in blue-green light and decreases in trap catch (Fig. 3-5). Blue-green

light ranging between 480nm and 510nm constituted approximately 13% of total light

emitted from fluorescent fixtures in all treatments (Table 3-4; Figs. 3-1 to 3-4). Both

Pickens and Thimijan (1986) and Shields (1989) have suggested that artificial cool-white

fluorescent light adversely affected house-fly attraction to UV light traps, but neither

study measured spectral output nor measured their effects on house-fly behavior. The

blue-green light emitted by cool-white fluorescent bulbs in the current study

corresponded directly with the blue-green sensitivity of the house-fly eye demonstrated in

previous studies (Figs. 3-1 to 3-4) (McCann and Arnett 1972, Bellingham 1995). These

results suggest that relatively high intensities of competing light containing blue-green

wavelengths may distract house flies from relatively low intensities of ultraviolet emitted

from light traps.

Approximately 1 to 2% of light emitted from cool-white fluorescent treatments

consisted of UV ranging between 350 to 370 nm (Table 3-4; Figs 3-1 to 3-4). Spectral

analyses showed the UV emission from fluorescent treatments exceeded the UV

originating from light traps by almost 4x when four bulbs were used (Table 3-4; Figs. 3-1









to 3-4). However, the spectrum of the UV consisted of a narrow spike that peaked at 365

nm contrasted with the broad-based UV from the light traps ranging from 310 to 399 nm

with a peak at 350 nm (Table 3-4; Figs. 3-1 to 3-4). Previous studies have demonstrated

that higher intensity of UV output significantly increased house fly catch within light

traps (Pickens and Thimijan 1986, Pickens 1989b, Snell 1998). But if house flies in this

study were simply responding to UV intensity, then one would expect to find a greater

number of flies remaining inside the release cage at the conclusion of the experiments.

Bowden and Church's studies (1973) documented an inverse relationship between

moonlight and trap catch for multiple species of beetles and moths. Since light intensity

decreases at a rate equal to the inverse square of distance from its source, Bowden and

Church (1973) asserted that light traps exerted a region of influence unique to individual

species. Insects outside of this region would remain unaffected by the trap, and

modifications to light-trap output or intensity of competing illumination would alter the

size of this region (Bowden and Church 1973). If the same concept applies to house flies,

then competing fluorescent light originating from multiple overhead light fixtures reduces

the region of influence of UV light traps by saturating the environment with full-

spectrum fluorescent light. Subsequently, Bowden (1982) estimated that a minimum

12:1 ratio of background light to trap light was necessary to have an adverse effect on

light trap performance. This ratio may hold for some species of Coleoptera or

Lepidoptera, but my lab studies found that background light intensity must be

approximately 25 times greater than light intensity from a trap to have a significant

adverse effect on house fly response (Bowden 1982). Although this may seem high,

intensity of competing light in urban environments can meet or exceed light levels









reported in this study (Table 3-1). In addition, as the intensity of UV light diminishes

over distance, the survey study showed that average light intensity from competing

sources remained relatively constant within each restaurant or grocery store (Table 3-1).

Impact of competing light spectra on trap catch. Results of the light quality

studies showed significantly fewer male (F = 21.28; df = 4, 64; P < 0.0001) and female

house flies (F = 37.85; df = 4, 64; P < 0.0001) were caught among all treatments when

compared against a dark control (Table 3-5). When the data were pooled together,

overall trap catch among all treatments was also significantly lower than the dark control

(F = 56.60; df = 4, 64; P < 0.0001), but significantly fewer flies were caught in light traps

when competing light consisted of black light versus daylight, cool-white, and warm-

white fluorescent (Tables 3-5 and 3-6; Figs. 3-5 to 3-8).

Blacklight bulbs emitted the lowest intensity of blue-green light while day light

bulbs emitted the highest intensity of blue-green (Table 3-6; Figs. 3-6 to 3-9). For this

study, regression analysis showed a significant correlation between increases in UV and

decreases in trap catch (Fig. 3-10). Intensity of UV emitted from Blacklight treatments

was approximately 10x greater than UV intensity from daylight, cool white, and warm

white treatments (Table 3-6; Figs. 3-6 to 3-9). In addition, the intensity of UV output

from all treatments exceeded UV emitted from light traps (Table 3-6; Figs. 3-6 to 3-9).

Yet the spectrum of the UV produced by daylight, cool white, and warm white

fluorescent bulbs consisted of a narrow spike peaking at 365 nm contrasted with

blacklight treatments and insect light traps which emitted broad-based UV ranging from

310 399 nm and peaking at 350 nm (Table 3-6; Figs. 3-6 to 3-9).









TheM. domestic eye is sensitive to UV light ranging from 340 nm to 370 nm and

blue-green light ranging from 480 nm to 510 nm, but there is debate over how this

sensitivity affects a house fly's optomotor response (Goldsmith and Fernandez 1968,

McCann and Arnett 1972, Thimijan and Pickens 1973, Green 1984). Although blue-

green sensitivity was relatively high, phototactic response by male and female M.

domestic gradually declined as light spectra approached 630 nm (Thimijan and Pickens

1973). Results from our light quality experiments were consistent with previous

literature indicating that house flies exhibited a stronger response toward UV versus blue-

green wavelengths (Pickens 1989a).

In conclusion, the results of our lab study showed a significant decrease in response

of male and female house flies toward UV light traps as the intensity of competing

fluorescent light was increased. When house flies were presented four different types of

competing light, their response towards UV light traps was significantly lower when

competing light sources contained broad-based UV versus blue-green light.









Table 3-1. Light intensity (lumens/m2) measured within five local restaurants (R) and
grocery stores (G)

Location n Intensity
A (G) 100 27.33 1.59
B (R) 100 28.29 0.37
C (R) 100 50.67 0.80
D (G) 100 61.43 2.42
E (R) 100 91.24 1.28



Table 3-2. Light intensity (lumens/m2) of four intensity treatments of cool-white
fluorescent light measured 45 cm from light source

Number of bulbs Total wattage Intensity

1 40 W 27.43
2 80 W 51.21
3 120 W 91.46
4 160 W 125.67






49


Table 3-3. Effect of intensity of cool-white fluorescent light as a competing light source
on number of adult house flies (mean SE) caught in UV light traps (50 M:
50 F per repetition)

Light intensity
Gender Dark control 27.43 51.43 91.46 125.67

Male 45.25 0.51a 42.66 1.31ab 41.88 1.16ab 40.00 1.49bc 37.00 1.15c
Female 47.00 + 0.58a 45.00 + 1.28ab 42.66 0.70bc 40.55 + 1.37cd 38.22 1.35d
Total 92.29 + 0.85a 87.66 + 1.45b 84.55 + 1.20b 80.55 + 0.97c 75.22 + 0.92d

Means within a row with the same letter are not significantly different (P=0.05; Student-
Newman Keuls [SAS Institute, 2001])












Table 3-4. Estimated intensity (lumens/m2) of total spectral output, blue-green output, and ultraviolet output emitted from competing
light sources and light traps used in light quantity experiments

Number of Estimated total Blue-green output UV output Blue-green Total
Cool white bulbs light intensity (480-510nm) (350-370nm) + UV output Trap Catch

1 33.01 3.36 0.70 4.06 87.66 + 1.45
2 59.23 6.46 1.03 7.49 84.55 + 1.20
3 104.22 11.85 1.26 13.11 80.55 0.97
4 140.60 16.66 1.59 18.65 75.22 + 0.92
UV Trap 1.95 0.06 0.44 0.50












Table 3-5. Effect of competing light quality on mean number ( SE) of adult house flies caught in UV light traps (50 M: 50 F per
repetition)

Competing light source

Gender Dark control Warm white Cool white Daylight Blacklight

Male 45.91 + 0.61a 40.25 + 1.15b 39.16 + 1.86b 39.66 + 0.91b 30.83 1.91c
Female 46.71 0.63a 35.66 2.14b 33.16 2.61b 34.50 1.21b 21.08 2.13c
Total 92.79 0.81a 75.91 2.72b 73.41 1.87b 74.16 1.63b 52.08 3.84c

Means within a row with the same letter are not significantly different (P=0.05; Student-Newman Keuls [SAS Institute, 2001])












Table 3-6. Estimated intensity (lumens/m2) of total spectral output, blue-green output, and ultraviolet output emitted from competing
light sources and light traps used in light quality experiments

Competing light Estimated total Blue-green output UV output Blue-green Total
spectrum light intensity (480-510nm) (350-370nm) + UV output Trap Catch

Blacklight 73.84 2.02 15.79 17.81 52.08 3.84
Day Light 76.61 11.94 1.27 13.21 74.16 1.63
Cool White 84.80 9.68 1.30 9.98 73.41 1.87
Warm White 89.62 10.57 1.73 12.30 75.91 2.72
UV Trap 1.95 0.06 0.44 0.50












Sylvania
Cool White
27.43 lumens/m2


200 300 400 500 600 700 800
Wavelength (nm)

Figure 3-1. Spectral analysis and mean intensity (lumens/m2) of 1 Sylvania Cool White
fluorescent bulb measured at 61 cm from source. Arrow highlights blue-green
peak between 480 and 510 nm.


Intensity (counts)
4000



3000



2000



1000











Sylvania
Cool White
51.21 lumens/m2


200 300 400 500 600 700 800
Wavelength (nm)

Figure 3-2. Spectral analysis and mean intensity (lumens/m2) of 2 Sylvania Cool White
fluorescent bulbs measured at 61 cm from source. Arrow highlights blue-
green peak between 480 and 510 nm.


Intensity (counts)
4000











Sylvania
Cool White
91.46 lumens/m2


200 300 400 500 600 700 800
Wavelength (nm)

Figure 3-3. Spectral analysis and mean intensity (lumens/m2) of 3 Sylvania Cool White
fluorescent bulbs measured at 61 cm from source. Arrow highlights blue-
green peak between 480 and 510 nm.


Intensity (counts)
4000



3000



2000



1000











Sylvania
Cool White
125.67 lumens/m2


200 300 400 500 600 700 800
Wavelength (nm)

Figure 3-4. Spectral analysis and mean intensity (lumens/m2) of 4 Sylvania Cool White
fluorescent bulbs measured at 61 cm from source. Arrow highlights blue-
green peak between 480 and 510 nm.


Intensity (counts)
4000



3000



2000



1000











90

88

86 y -0.9108x + 90.723
R284 = 0.9933
-c 84

S82

80 -

78

76

74
0 2 4 6 8 10 12 14 16 18
Intensity of Blue-green light (480-510nm)


Figure 3-5. Regression analysis showing relationship between trap catch and intensity
(lumens/m2) of blue-green light











/


Sylvania
Blacklight Bulb
43.46 + 1.84 lumens/m2


200 300 400 500 600 700 800
Wavelength (nm)
Figure 3-6. Spectral analysis and mean intensity (lumens/m2) of Sylvania Blacklight
bulbs measured at 61 cm from source. Arrow highlights UV peak between
340 and 370 nm.


Intensity (counts)
4000


3000


2000+












Sylvania
Daylight Bulb
65.9 + 1.08 lumens/m2


200 300 400 500 600 700 800
Wavelength (nm)

Figure 3-7. Spectral analysis and mean intensity (lumens/m2) of Sylvania Daylight
fluorescent bulbs measured at 61 cm from source. Arrow highlights blue-
green peak between 480 and 510 nm.


Intensity (counts)
4000




3000




2000




1000












Intensity (counts)


1000




200 300 400


Sylvania
Cool White Bulb
73.81 + 0.69 lumens/m2


500
Wavelength (nm)


Figure 3-8. Spectral analysis and mean intensity (lumens/m2) of Sylvania Cool White
fluorescent light measured at 61 cm from source. Arrow highlights blue-green
peak between 480 and 510 nm.











Sylvania
Warm White Bulb
74.04 + 0.59 lumens/m2


500
Wavelength (nm)


Figure 3-9. Spectral analysis and mean intensity (lumens/m2) of Sylvania Warm White
fluorescent light measured at 61 cm from source. Arrow highlights blue-green
peak between 480 and 510 nm.


Intensity (counts)
4000



3000



2000



1000


300














y = -1.5558x + 76.704
R2 = 0.9854


10
Intensity of Ultraviolet (350-370nm)


Figure 3-10. Regression analysis showing relationship between trap catch and intensity
(lumens/m2) of blue-green light














CHAPTER 4
LIGHT TRAP HABITUATION STUDY

Introduction

The house fly Musca domestic (Diptera: Muscidae) is a nuisance in agricultural

and urban environments (Cosse and Baker 1996, Moon 2002, Hogsette 2003). High

populations of house flies can cause economic losses in livestock, and dispersing house

flies are pestiferous in residential and commercial areas (Hogsette and Farkas 2000).

House flies breed in animal waste, dumpsters, and garbage and have been implicated as

mechanical vectors of enteric diseases such as Salmonella spp. and ./nge//la spp. among

animals and humans (Imai 1984, Graczyk et al. 2001, Mian et al. 2002).

In urban areas, UV light traps are used to manage house flies. Insect light traps that

utilize ultra-violet light were developed as an alternative to insecticide applications. As

house flies enter structures they are exposed to artificial light through time, but it is

unknown whether continued exposure to artificial light influences their sensitivity to UV

light traps. If house flies habituate to background light in their surrounding environment,

then they may be more inclined or disinclined to fly towards a UV-light trap. Therefore,

the objective of this study was to determine if previous experience with fluorescent or

UV light influences house fly response to UV light traps.

Materials and Methods

Insects. The Horse-Teaching Unit (HTU) strain of house fly, M. domestic, from

Gainesville, FL, was used for all studies presented here. Larvae were reared on a

medium containing 3 liters wheat bran, 1.5 liters water, and 250 ml of Calf Manna









(Manna Pro Corp., St. Louis, MO) pellets. All stages of HTU strain were placed on a

12:12 (L: D) photoperiod at 260C + 1IC and -55% RH. Adult flies from both strains

were provided granulated sugar, powdered milk, and water ad libitum and held on a

12:12 photoperiod (L:D) (Hogsette 1992, Hogsette et al. 2002). Adult flies were held no

longer than 7 d.

Prior to experimentation, adult flies were aspirated from screen cages using a

handheld vacuum with modified crevice tool to aspirate adult flies. Aspirated flies were

transferred into a refrigerator (-50C) for 2 min to subdue activity. Subdued flies were

removed from the refrigerator and placed on a chilled aluminum tray, then counted and

sexed. Counted and sexed flies were placed into deli cups (237 ml) and held at room

temperature for approximately 30 min. All flies were handled with camel hair

paintbrushes and featherweight forceps to prevent damage.

Light tunnel design. Enclosed light-tunnel design consisted of a release cage

attached to a galvanized aluminum light tunnel that terminates in a box enclosing a light

trap (Fig. 1). The release cage (30 by 30 by 45 cm) was fitted with a sheet-metal bottom

and aluminum window screen on the top, sides, and one end. Stockinette was fitted on

the remaining end (30 by 30 cm) to allow access into the cage. Release cages were

placed on a 10.4 cm platform to make them level with a light tunnel entrance. The light

tunnel (152 by 20 dia. cm metal duct) was primed and painted with one coat of primer

and one coat of flat black paint, then allowed to cure for at least 3 d to eliminate paint

fumes. A light-tunnel entrance (20 cm dia.) was cut into the box enclosure (66 by 91 by

60 cm) which was constructed of corrugated cardboard. The 20 cm hole was centered

horizontally on 91 cm face, and it was 12.7 cm from ground level. Vents were cut into









the top of the box enclosure (17.7 by 38.1 cm) to prevent buildup of heat from light traps.

A piece of black organdy was glued over each vent to prevent flies from escaping. A

piece of plywood (91 by 60 cm) was painted with white paint and placed inside the box

enclosure opposite the light tunnel entrance. One UV light trap (Nova, Whitmire

Microgen Inc., St. Louis, MO) was mounted with four screws onto the white plywood

inside the box enclosure. The trap was laterally centered and located directly opposite

the light tunnel entrance. The trap utilized three 15-watt UV bulbs (Sylvania

QuantumTM, Manchester, UK) as well as horizontal (7.6 by 40.6 cm) and vertical (25.4 by

40.6 cm) glue boards. Ultra-violet light bulbs in light traps had less than 1000 h use. A

workshop light containing two 40-watt Sylvania cool-white fluorescent light bulbs was

hung 8 cm above release cages to provide a source of background light that is a common

light source in urban environments.

Procedure. All experiments were conducted inside two buildings (3 by 3 m); each

building held two light tunnels. New glue boards were placed inside traps and all lights

were turned on. One hundred counted and sexed adult flies were released from a plastic

cup (237 ml) into a release cage. Experiments commenced when stockinette on the

release cages was unfurled and wrapped around the entrance of the light tunnel, allowing

access to the UV light trap. At the end of each experiment the release cages were sealed

and removed, traps were turned off and glue boards were collected. Flies not captured

were removed from the experimental set up prior to subsequent repetitions. Ambient

temperature for all experiments was 290C.

Quality and quantity of light were recorded at the release-cage end of the light

tunnel (Fig. 2). Spectral analyses and relative light intensities were measured using a









USB2000 Spectrometer (Ocean Optics, Dunedin, FL). Absolute light quantity for

cool-white fluorescent light output and UV-trap output was measured with a HOBO

Light Intensity logger (Onset', Bourne, MA).

Light habituation treatments. All house flies in primary lab colonies were reared

on a 12:12 (L:D) photoperiod using 4 40-watt GE Wide Spectrum Plant and Aquarium

bulbs (GE F40PL/AQ) at intensity of 10.28 2.38 lumens/m2. Prior to habituation

experiments, house fly pupae were separated from primary lab colonies, placed in a

screen holding cage (30 by 17.5 by 30 cm) and stored in a separate rearing room.

Holding cages were covered on top and three sides with aluminum foil to prevent

overhead light from entering the cages. The side of the holding cage (30 by 17.5 cm) that

was not covered by aluminum foil was placed 12 cm away directly in front of a light

fixture. Light fixtures provided either cool-white fluorescent light from four 15W

Sylvania Cool White bulbs or UV light from four 15W Sylvania QuantumTM Blacklight

bulbs. Cool white fluorescent light was selected for this treatment because it is a

common source of indoor lighting. Emerging adult house flies in holding cages were

reared on a 12:12 photoperiod (L:D) of either cool-white fluorescent light at intensity of

34.11 0.54 lumens/m2 or black light bulbs at intensity of 15.88 0.39 lumens/m2 for 2

to 3 d prior to experiments. All house flies were provided with powdered milk,

granulated sugar, and water ad libitum.

Statistical analysis. Since both treatments for the habituation experiments could

not be conducted simultaneously, this study was set up using a two-way balanced

incomplete block design. Treatment pairs were randomly assigned apriori for each trial

day until all possible treatment combinations were met (SAS 2001). A dark control was









run concurrently with each repetition. For each dark control, house flies were placed into

a release cage and presented with an illuminated light trap at the end of the light tunnel

without a competing light source placed overhead. The house flies used in all controls

were selected from the original laboratory colonies. A Whitmire Nova light trap was

used in all dark controls.

Results and Discussion

Although all treatments caught significantly fewer house flies than the dark control,

there was no significant difference in the response to UV light traps among house flies

reared on UV light, cool-white light, versus the plant and aquarium light used in the

laboratory (F = 11.47; df= 3, 21; P < 0.0001) (Table 4-1). Rearing house flies on

blacklight or cool-white fluorescent did not influence their response to UV light traps

(Table 4-1; Figs. 4-1 to 4-3). If house flies did habituate to blacklight, then we would

have expected a significantly lower response to UV light traps. Conversely, if they

habituated to cool-white fluorescent, then we would have expected to see a significant

increase in their response to UV light traps.

Fukushi (1976) demonstrated that house flies could discriminate among narrow

ranges of light wavelengths when specific wavelengths were associated with sugar water.

Although this experiment of classical conditioning was not directly related with my

experiment, it does illustrate that visual experience with specific wavelengths of light can

influence house fly behavior (Fukushi 1976).

Pickens et al. (1969) speculated that adult house flies exposed to UV-light traps for

at least 12 h exhibited a significantly greater response towards light traps compared with

adult house flies that did not have previous visual experience with UV. This result would

suggest that house flies developed increased sensitivity to UV, not habituation (Pickens et









al. 1969). But our results showed that that prior exposure to UV light did not significantly

increase or decrease catch efficacy of light traps (Table 4-1). Subsequent studies on

visual sensitivity of house flies showed that dark-reared flies responded to significantly

lower intensity levels of light than house flies reared on a 12:12 (L:D) photoperiod

(Deimel and Kral 1992). Thus, Deimel and Kral (1992) determined that fly vision

developed within the initial 1-5 d after adult emergence and suggested that visual

experience within this time frame may influence the flies' sensitivity to light. However,

their research did not compare sensitivity across different light spectra, but rather light

intensity needed to stimulate the optic nerve (Deimel and Kral 1992). These results show

that the spectrum of light presented to house flies during this developmental period did

not influence house fly response to overhead or UV light when placed in a bioassay that

provides them with a choice of light spectra.






69


Table 4-1. Mean number of adult house flies caught in UV light traps after being pre-
conditioned under different light conditions.

Pre-conditioning light treatments

Gender Control Wide spectrum Black light Cool white

Male 45.22 + 0.51a 40.66 + 1.31b 36.33 1.16b 36.66 + 1.49b
Female 44.00 + 0.58a 41.16 + 1.28b 40.33 0.70b 40.50 + 1.37b
Total 89.22 0.85a 81.82 + 2.45b 76.66 + 1.20b 77.16 + 1.97b

Means within a row with the same letter are not significantly different (P=0.05; Student-
Neuman Keuls [SAS Institute, 2001]).











Rearing Room
GE Plant & Aquarium
10.28 2.38 lumens/m2


200 300 400 500 600 700 800
Wavelength (nm)

Figure 4-1. Spectral analysis and mean intensity of GE Plant & Aquarium fluorescent
light used in house fly rearing room. Mean light intensity presented in
lumens/m2.


Intensity (counts)
4000t












Sylvania
Blacklight
15.88 0.39 lumens/m2


200 300 400 500 600 700 800
Wavelength (nm)

Figure 4-2. Spectral analysis and mean intensity of Sylvania Blacklight used to rear
treatment house flies. Mean light intensity presented in lumens/m2.


Intensity (counts)
4000




3000




2000




1000











Sylvania
Cool White
34.11 0.54 lumens/m2


200 300 400 500 600 700 800
Wavelength (nm)

Figure 4-3. Spectral analysis and mean intensity of Sylvania Cool White fluorescent
light used to rear treatment house flies. Mean light intensity presented in
lumens/m2.


Intensity (counts)
4000



3000



2000



1000














CHAPTER 5
SUMMARY AND CONCLUSIONS

The main purpose of this research was to investigate factors in the urban

environment that inhibit the catch efficacy of UV light traps used to manage the house

fly, Musca domestic, in urban environments. To do this, the first priority was to develop

a standard bioassay that eliminated or reduced position effects associated with light-trap

placement that influence results. Initial studies with a light tunnel bioassay demonstrated

there were no significant position effects detected among two research buildings, four

positions, or box enclosures which enclosed the light traps. In addition, the light-tunnel

bioassay minimized air movement and standardized trap location, trap distance, and

background light for future experiments.

The first portion of this research investigated the effect of house fly age on its

response to UV light traps. House flies that were 5 d and younger exhibited significantly

greater attraction toward UV light traps than older flies. The second part of the first

research chapter used probit analysis to estimate response time of house flies to UV traps.

A catch time for 50% of house flies (CT5o) within UV traps was estimated from 99 114

min for males and females. The estimated CT50 for total house fly response toward an

UV light trap was approximately 1.72 h (103.2 min). The CT90 and CT95 estimates for

total house fly catch were 6.01 h (360.6 min) and 8.57 h (514.2 min) respectively. There

was no significant difference between male and female response time as evident by

overlapping 95% confidence intervals for CT50, CT90, and CT95.









For the second portion of this research, house flies were presented various intensity

levels of cool-white fluorescent light in order to determine whether intensity of non-UV

competing light sources influenced house fly attraction to UV light traps. Intensity levels

in experiments correlated with preliminary surveys of overhead and natural light within

local grocery stores and restaurants where light traps are commonly used. Results

showed that the number of males caught in UV traps significantly decreased when

intensity of the competing light exceeded 91.43 lumens / m2. Significant declines in

catch of females occurred at a lower intensity when the competing light exceeded 51.43

lumens / m2. When the data were combined, the overall results showed total catch in UV

light traps decreased significantly as the intensity of competing light source increased.

These results demonstrated a significant decrease in response of male and female house

flies toward UV light traps as the intensity of competing fluorescent light was increased.

House flies were also presented with four different types of competing light which

covered a broad spectral range from UV to red (700 nm) which is beyond the house fly's

visual perception. Again, house fly response toward UV light traps significantly declined

when a source of competing light was introduced. However, house fly response towards

UV light traps was significantly lower when background light contained broad-based UV

versus background light containing blue-green light and no UV.

Finally, the third portion of this research investigated whether or not house flies

habituated to light quality within their surrounding environment. House flies from

current colonies were compared against house flies reared on black light and cool-white

fluorescent light. The results of habituation experiments showed that all treatments

caught significantly fewer house flies than the dark control. However, there was no






75


significant difference in the response to UV light traps among house flies reared on UV

light, cool-white fluorescent light, and grow-lights which are used in the rearing rooms.

The spectrum of light used in rearing did not significantly influence house fly response to

UV light traps. These results also suggest that previous experience to different kinds of

light does not influence house fly response to light traps.















APPENDIX A
DIAGRAM OF BUILDING LAYOUT


Building

- Position



- Box Enclosure








- Location of Light
Measurements


Overhead
Fluorescent
Light Fixture


bi b2


3 4


Release Cage


Figure A-1. Diagram of buildings, positions, and bioassay layout at USDA


ai



1


A
a2 -



2.41


Xi IX














APPENDIX B
SAS PROGRAMS USED FOR DATA ANALYSIS

SAS programs for Chapter 2


/Analysis of variance for study standardizing the bioassay/
/ 'Position' is nested within 'Building'/

Proc glm data = work.fly;
Class building (position);
Model male fern total = building (position);
Means building (position) / snk;

Run;

/Analysis of variance for age study/

Proc glm data = work.fly;
Class age;
Model male fern total = age;
Means age / snk;

Run;

/Probit analyses for Time study/

/Probit analysis for total number of flies caught on glue boards/

Proc probit data = work.fly inversecl loglO lackfit;
Class gbtot;
Model time/n = hrs /;
Run;
/N = 500/

/Probit analysis for adult male house flies caught on glue boards/
Proc probit data = work.fly inversecl loglO lackfit;
Class male;
Model time/n = hrs /;
Run;
/N1 = 250/









/Probit analysis for adult female house flies caught on glue boards/
Proc probit data = work.fly inversecl loglO lackfit;
Class female;
Model time/n = hrs /;
Run;
/N1 = 250/

/Analysis of variance comparing light output of four UV light traps/

Proc sort data = work.light;
By trap;

Proc glm data = work.light;
Class trap;
Model intensity = trap;
Means trap / SNK;

Run;

/Analysis of variance comparing overhead cool-white fluorescent light measured at four
independent positions/

Proc sort data = work.light;
By position;

Proc glm data = work.light;
Class position;
Model intensity = position;
Means position / SNK;


Run;









SAS programs for Chapter 3


Proc sort data = work.fly; by day treatment;

Proc univariate data = work.fly;
Class treatment;
Var total male fem;

Run;

/ Balanced Incomplete Block Design (BIBD); Two-way analysis of variance (BIBD) of
light intensity data /

Proc sort data = work.fly; by day treatment;

Proc glm data = work.fly;
Class day treatment;
Model male fem total = day treatment;
Means treatment / snk;
Lsmeans treatment / pdiff;

Proc glm data = work.fly;
Class day treatment;
Model armale arfem artotal = day treatment;
Means treatment / snk;
Lsmeans treatment / pdiff;

Proc sort data = work. sex;
by treatment;

Proc glm data = work.sex;
by treatment;

Class sex;
Model resp aresp = sex;
Means sex / snk;

Proc sort data = work. sex; by sex;

Proc glm data = work.sex; by sex;
Class treatment;
Model resp aresp = treatment;
Means treatment / snk;


Run;









/Proc univariate for light quality data/

Proc sort data = work.fly; by day treatment;

Proc univariate data = work.fly;
Class treatment;
Var total male fern;

/Balanced Incomplete Block Design; Two-way analysis of variance (BIBD) of light
quality data/

Proc sort data = work.fly; by day treatment;

Proc glm data = work.fly;
Class day treatment;
Model male fern total = day treatment;
Means treatment / snk;
Lsmeans treatment / pdiff;

Proc glm data = work.fly;
Class day treatment;
Model armale arfem artotal = rep treatment;
Means treatment / snk;
Lsmeans treatment / pdiff;

Proc sort data = work. sex;
by treatment;

Proc glm data = work.sex;
by treatment;

Class sex;
Model resp aresp = sex;
Means sex / snk;

Proc sort data = work. sex; by sex;

Proc glm data = work.sex; by sex;
Class treatment;
Model resp aresp = treatment;
Means treatment / snk;

Run;









SAS Programs for Chapter 4


Proc sort data = work.fly;
by day treatment;

Proc univariate data = work.fly;
Class treatment;
Var total male fern;

Run;

/ Balanced Incomplete Block Design (BIBD); Two-way analysis of variance (BIBD) for
light habituation data/


Proc sort data = work.fly;
by day treatment;

Proc glm data = work.fly;
Class rep treatment;
Model male fem total = day treatment;
Means treatment / snk;
Lsmeans treatment / pdiff;


Proc glm data = work.fly;
Class day treatment;
Model armale arfem artotal
Means treatment / snk;
Lsmeans treatment / pdiff;


Proc sort data = v
by treatment;

Proc glm data = v
Class sex;
Model resp aresp
Means sex / snk;


Proc sort data
by sex;


day treatment;


york.sex;


vork.sex; by treatment;

= sex;


work. sex;


Proc glm data = work.sex; by sex;
Class treatment;
Model resp aresp = treatment;
Means treatment / snk;


Run;


















APPENDIX C
SPECTROMETRY MEASUREMENTS FOR LIGHT TRAPS AND BACKGROUND
LIGHT


Intensity (counts)
4000
Trap 1


Position ai


Mean light intensity
1.33 + 0.15 lumens/m2


3000



2000




1000


400


500
Wavelength (nm)


800


Figure C-1. Spectral analysis and mean light intensity of Whitmire Nova trap 1 at
Position ai










Position a2

Mean light intensity
1.34 + 0.09 lumens/m2


200 300 400 500 600 700 800
Wavelength (nm)
Figure C-2. Spectral analysis and mean light intensity of Whitmire Nova trap 2 at
Position a2


Intensity (counts)


Trap 2


J A











Intensity (counts)
4000} Trap 3


Position bl

Mean light intensity
1.35 + 0.14 lumens/m2


200 300 400 500 600 700 800
Wavelength (nm)

Figure C-3. Spectral analysis and mean light intensity of Whitmire Nova trap 3 at
Position bi











Intensity (counts)
4000
Trap 4


Position b2

Mean light intensity
1.33 + 0.17 lumens/m2


200 300 400 500 600
Wavelength (nm)

Figure C-4. Spectral analysis and mean light intensity
Position b2


of Whitmire Nova trap 4 at












Intensity (counts) Position al
4000
55.92 lumens/m2


3000




2000




1000




200 300 400 500 600 700 800
Wavelength (nm)

Figure C-5. Spectral analysis and mean intensity of overhead cool-white fluorescent light
at Position ai












Intensity (counts)
4000


Position a2


53.67 lumens/m2


1000




200 300 400 500 600 700 800
Wavelength (nm)

Figure C-6. Spectral analysis and mean intensity overhead cool-white fluorescent light at
Position a2






Position bl
54.88 lumens/m2


Intensity (counts)
4000

3000

2000


200 300 400 500 600 700 800
Wavelength (nm)
Figure C-7. Spectral analysis and mean intensity overhead cool-white fluorescent light at
Position bi


-:







89



Intensity (counts) Position b2
4000
55.01 lumens/m2


3000



2000



1000




200 300 400 500 600 700 800
Wavelength (nm)

Figure C-8. Spectral analysis and mean intensity overhead cool-white fluorescent light at
Position b2




Full Text

PAGE 1

BIOLOGICAL AND PHYSICAL FACTORS AFFECTING CATCH OF HOUSE FLIES IN ULTRAVIOLET LIGHT TRAPS By MATTHEW D. AUBUCHON A DISSERTATION PRESENTED TO THE GRADUATE SCHOOL OF THE UNIVERSITY OF FLOR IDA IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY UNIVERSITY OF FLORIDA 2006

PAGE 2

Copyright 2006 by Matthew D. Aubuchon

PAGE 3

iii ACKNOWLEDGMENTS I would like to sincerely tha nk Dr. Phil G. Koehler for dire cting the course of this dissertation and my graduate program. I would also like to acknowledge and thank Dr. Faith Oi, Dr. Norm Leppla, Dr Nancy Hinkle, Dr. Jerry H ogsette, and Dr. Ron Randles for their service on my supervisory committ ee. Ricky Vasquez, Ryan Welch, and Jeff Hertz provided valuable assi stance with house-fly rearing. Dr. Phil Kaufman graciously made space in his laboratory for us to rear our house flies and provided valuable rearing advice. Debbie Hall was extraordinarily helpfu l to me with registra tion, research credits, graduate-school deadlines, and all other associ ated paperwork. I would like to thank my family for their support through this process. Finally, I would like to thank my beautiful wife Amanda for her love, support, encouragement, and patience throughout my graduate school experience.

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iv TABLE OF CONTENTS page ACKNOWLEDGMENTS.................................................................................................iii LIST OF TABLES.............................................................................................................vi LIST OF FIGURES..........................................................................................................vii ABSTRACT....................................................................................................................... ..x CHAPTER 1 INTRODUCTION AND LITERATURE REVIEW....................................................1 The House Fly Musca domestica ..................................................................................1 Importance of Musca domestica ...................................................................................1 Nuisance................................................................................................................1 Disease Transmission............................................................................................2 Biology of Musca domestica ........................................................................................4 Oviposition............................................................................................................4 Larval Development and Survival.........................................................................4 Adult Behavior......................................................................................................6 Activity and longevity....................................................................................6 Photoperiod....................................................................................................7 Dispersal.........................................................................................................8 Attractants for Musca domestica ..................................................................................9 Chemical Attractants.............................................................................................9 Physical Attractants...............................................................................................9 Color...............................................................................................................9 Surfaces........................................................................................................10 Light.............................................................................................................11 Control Using Attractants...........................................................................................13 Chemical Baits.....................................................................................................13 Physical Traps.....................................................................................................13 Insect Light Traps (ILT)......................................................................................14 House Fly Response to ILTs........................................................................14 Design and Location of ILTs.......................................................................15 Competing Light Sources.............................................................................16 Statement of Purpose..................................................................................................18

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v 2 ESTIMATES OF RESPONSE TIME BY HOUSE FLIES TOWARD UV LIGHT TRAPS USING LIGHT-TUNNEL BIOASSAY.......................................................20 Introduction.................................................................................................................20 Materials and Methods...............................................................................................21 Results and Discussion...............................................................................................25 3 INFLUENCES OF QUALITY AND INTENSITY OF BACKGROUND LIGHT ON HOUSE FLY RESPONSE TO LIGHT TRAPS..................................................37 Introduction.................................................................................................................37 Materials and Methods...............................................................................................38 Results and Discussion...............................................................................................43 4 LIGHT TRAP HABITUATION STUDY..................................................................63 Introduction.................................................................................................................63 Materials and Methods...............................................................................................63 Results and Discussion...............................................................................................67 5 SUMMARY AND CONCLUSIONS.........................................................................73 APPENDIX A DIAGRAM OF BU ILDING LAYOUT.....................................................................76 B SAS PROGRAMS USED FOR DATA ANALYSIS.................................................77 SAS programs for Chapter 2.......................................................................................77 SAS programs for Chapter 3.......................................................................................79 SAS Programs for Chapter 4......................................................................................81 C SPECTROMETRY MEASUREMEN TS FOR LIGHT TRAPS AND BACKGROUND LIGHT...........................................................................................82 D REARING CONDITIONS FOR CONLONIES OF MUSCA DOMESTICA .............90 LIST OF REFERENCES...................................................................................................96 BIOGRAPHICAL SKETCH...........................................................................................105

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vi LIST OF TABLES Table page 2-1 Effect of building, position within bu ilding, and box enclosure on the number of house flies caught in UV light trap s (50 M: 50 F per repetition).............................30 2-2 Influence of age and sex on number of house flies caught in UV light traps (50 M: 50 F per repetition)...................................................................................................31 2-3 Cumulative house-fly catch in UV light trap s over time (50 M: 50 F per repetition)32 2-4 Estimated time (h) to catch of adult house flies by UV light traps using Probit analysis.....................................................................................................................33 3-1 Light intensity (lumens/m2) measured within five local restaurants (R) and grocery stores (G)..................................................................................................................48 3-2 Light intensity (lumens/m2) of four intensity treatmen ts of cool-white fluorescent light measured 45 cm from light source...................................................................48 3-3 Effect of intensity of cool-white fl uorescent light as a competing light source on number of adult house flies (mean SE) caught in UV light traps (50 M: 50 F per repetition).................................................................................................................49 3-4 Estimated intensity (lumens/m2) of total spectral output, blue-green output, and ultraviolet output emitted from competing li ght sources and light traps used in light quantity experiments................................................................................................50 3-5 Effect of competing light quality on mean number ( SE) of adult house flies caught in UV light traps (50 M: 50 F per repetition)...............................................51 3-6 Estimated intensity (lumens/m2) of total spectral output, blue-green output, and ultraviolet output emitted from competing li ght sources and light traps used in light quality experiments..................................................................................................52 4-1 Mean number of adult house flies ca ught in UV light traps after being preconditioned under different light conditions............................................................69

PAGE 7

vii LIST OF FIGURES Figure page 2-1 Light tunnel design illustrating rel ease cage (30 by 30 by 45 cm) (foreground), overhead light source (101.6 cm), light t unnel (152 by 20 cm), and box enclosure (66 by 91 by 60 cm) cont aining light trap................................................................34 2-2 Intensity (lumens / m2) of UV-light tr ap with relative intensity of light by wavelength...............................................................................................................35 2-3 Intensity (lumens/m2) of cool-white fluorescent light with relative intensity of light by wavelength..........................................................................................................36 3-1 Spectral analysis and mean intensity (lumens/m2) of 1 Sylvania Cool White fluorescent bulb measured at 61 cm from s ource. Arrow highlights blue-green peak between 480 and 510 nm..........................................................................................53 3-2 Spectral analysis and mean intensity (lumens/m2) of 2 Sylvania Cool White fluorescent bulbs measured at 61 cm from source. Arrow highlights blue-green peak between 480 and 510 nm.................................................................................54 3-3 Spectral analysis and mean intensity (lumens/m2) of 3 Sylvania Cool White fluorescent bulbs measured at 61 cm from source. Arrow highlights blue-green peak between 480 and 510 nm.................................................................................55 3-4 Spectral analysis and mean intensity (lumens/m2) of 4 Sylvania Cool White fluorescent bulbs measured at 61 cm from source. Arrow highlights blue-green peak between 480 and 510 nm.................................................................................56 3-5 Regression analysis showing relations hip between trap catch and intensity (lumens/m2) of blue-green light...............................................................................57 3-6 Spectral analysis and mean intensity (lumens/m2) of Sylvania Blacklight bulbs measured at 61 cm from source. Ar row highlights UV peak between 340 and 370 nm............................................................................................................................. 58 3-7 Spectral analysis and mean intensity (lumens/m2) of Sylvania Daylight fluorescent bulbs measured at 61 cm from source. Arrow highlights blue-green peak between 480 and 510 nm........................................................................................................59

PAGE 8

viii 3-8 Spectral analysis and mean intensity (lumens/m2) of Sylvania Cool White fluorescent light measured at 61 cm from source. Arrow highlights blue-green peak between 480 and 510 nm.................................................................................60 3-9 Spectral analysis and mean intensity (lumens/m2) of Sylvania Warm White fluorescent light measured at 61 cm from source. Arrow highlights blue-green peak between 480 and 510 nm.................................................................................61 3-10 Regression analysis showing relations hip between trap catch and intensity (lumens/m2) of blue-green light...............................................................................62 4-1 Spectral analysis and mean intensity of GE Plant & Aquarium fluorescent light used in house fly rearing room. Mean light intensity presented in lumens/m2.......70 4-2 Spectral analysis and mean intensity of Sylvania Blacklight used to rear treatment house flies. Mean light inte nsity presented in lumens/m2.......................................71 4-3 Spectral analysis and mean intensity of Sylvania Cool White fluorescent light used to rear treatment house flies. M ean light intensity presented in lumens/m2...72 A-1 Diagram of buildings, positions, and bioassay layout at USDA..............................76 C-1 Spectral analysis and mean light intensity of Whitmire Nova trap 1 at Position a1.82 C-2 Spectral analysis and mean light intensity of Whitmire Nova trap 2 at Position a2.83 C-3 Spectral analysis and mean light intensity of Whitmire Nova trap 3 at Position b184 C-4 Spectral analysis and mean light intensity of Whitmire Nova trap 4 at Position b285 C-5 Spectral analysis and mean intensity of overhead cool-white fluorescent light at Position a1.................................................................................................................86 C-6 Spectral analysis and mean intensity overhead cool-white fluorescent light at Position a2.................................................................................................................87 C-7 Spectral analysis and mean intensity overhead cool-white fluorescent light at Position b1................................................................................................................88 C-8 Spectral analysis and mean intensity overhead cool-white fluorescent light at Position b2................................................................................................................89 D-1 Temperature (C) of rearing room for adult Musca domestica recorded by HOBO Temp & RH data logger...........................................................................................90 D-2 Relative Humidity (%) of rearing room for adult Musca domestica recorded by HOBO Temp & RH data logger...............................................................................91

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ix D-3 Light intensity (lumens/m2) of rearing room for adult Musca domestica recorded by HOBO Light Intensity data logger. Graph illustrate s 12:12 (L:D) photoperiod.....92 D-4 Temperature (C) of rearing room for Musca domestica larvae recorded by HOBO Temp & RH data logger...........................................................................................93 D-5 Relative Humidity (%) of rearing room for Musca domestica larvae recorded by HOBO Temp & RH data logger...............................................................................94 D-6 Light intensity (lumens/m2) of rearing room for Musca domestica larvae recorded by HOBO Light Intensity data logger. Gr aph illustrates 12:1 2 (L:D) photoperiod95

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x Abstract of Dissertation Pres ented to the Graduate School of the University of Florida in Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy BIOLOGICAL AND PHYSICAL FACTORS AFFECTING CATCH OF HOUSE FLIES IN ULTRAVIOLET LIGHT TRAPS By Matthew D. Aubuchon May 2006 Chair: Phil Koehler Major Department: Entomology and Nematology A bioassay for studying light tr ap efficacy for the house fly Musca domestica L. (Diptera: Muscidae) was developed to overc ome position effects asso ciated with lighttrap placement. After initial studies, no si gnificant effects of position were detected among two research buildings, four positions, or box enclosures used. The light-tunnel bioassay provided standardized air move ment, trap location, trap distance, and background light for future experiments inve stigating house fly age and response time. House flies that were 5 d and younger showed significantly greater attraction toward UV light traps than older flies. A probit analys is estimated that catch time for 50% of house flies (CT50) toward UV traps ranged from 99 to 114 min for males and females respectively. Estimated CT50 for total house fly response toward UV light trap was approximately 1.72 h (103.2 min). The CT90 and CT95 estimates for total house fly catch were 6.01 h (360.6 min) and 8.57 h (514.2 min) fo r males and females respectively. No

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xi significant difference between male and fe male response time was seen by overlapping 95% confidence intervals for CT50, CT90, and CT95. When flies were presented gr eater intensity levels of c ool-white fluorescent light, the number of males caught in UV traps signifi cantly decreased when intensity of the competing light exceeded 51.43 lumens/m2. Significant declines in catch of females occurred at a lower intensity when the competing light exceeded 27.43 lumens/m2. When the data were combined, overall results show ed that the total catch in UV light traps decreased significantly as the intensity of competing light source increased. Results of our lab study showed a signifi cant decrease in re sponse of male and female house flies toward UV light traps as the intensity of competing fluorescent light was increased. When house flies were presented four di fferent types of co mpeting light, all responses were significantly different when co mpared with the dark control. However, house fly response toward UV light traps was significantly lower when background light contained broad-based UV versus background light containing blue-green light. For habituation experiments, all treatmen ts caught significantly fewer house flies than the dark control. However, there wa s no significant difference in the response to UV light traps among house flies reared on UV li ght, cool-white fluorescent light, and the grow-lights used in the reari ng rooms. The quality of li ght used in rearing did not significantly influence house fl y response to UV light traps.

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1 CHAPTER 1 INTRODUCTION AND LITERATURE REVIEW The House Fly Musca domestica The house fly Musca domestica L. (Diptera: Muscidae) is a synanthropic filth fly that breeds in garbage, and animal a nd human feces (Schoof and Silverly 1954a, Greenberg 1973, Imai 1984, Graczyk et al. 2001). It is a dull gray insect and may be identified by four longitudinal stripes on th e dorsum of the thorax and a sharp angle on the fourth longitudinal wing vein (West 1951) The house fly does not bite as it is equipped with sponging-rasping mouthpa rts (West 1951, McAlpine 1987). Musca domestica L. is classified in the order Diptera and family Muscidae (McAlpine 1987, Borror et al. 1989). Flies in the family Muscidae generally have strong setae dispersed over the enti re body, dull color, and reduced wing veination (West 1951, McAlpine 1987). The Genus Musca encompasses approximately 24 species with 2 subspecies of M. domestica (West 1951). Because house flies adapt to human environments, they are found on all contin ents except Antarctica (West 1951, McAlpine 1987). Importance of Musca domestica Nuisance House flies are a nuisance in agricultural and urban environments (Cosse and Baker 1996, Moon 2002, Hogsette 2003). Large popula tions populations originating from animal manure can cause economic losses in livestock (Axtell 1970, Hogsette and Farkas 2000). Dispersing house flies ar e pestiferous in residentia l and commercial areas and

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2 present a public health problem to home a nd business owners near agricultural areas (Axtell 1970, Hogsette 2003). Breeding sites such as animal waste and garbage dumpsters contribute to probl ems associated with house flies in urban environments (Schoof and Silverly 1954b, Morris and Hansen 1966). Disease Transmission House flies have been implicated as mech anical vectors of a range of enteric pathogens among animals and humans (Schoof and Silverly 1954a, Greenberg 1973, Imai 1984, Graczyk et al. 2001). Viruses, bacteria, and protozoans cling to house fly wings, setae, tarsi, and mouthparts and are dislodge d onto a variety of surfaces (Graczyk et al. 2001). In poultry houses and dairy units, house flies were a primary vector of Salmonella spp. (Mian et al. 2002). Salmonella spp. and Shigella spp. (which causes morbidity and mortality associated with infantile gastroente ritis), are also transmitted by house flies to humans (Bidawid et al. 1978). Levine and Le vine (1991) reported th at the incidence of dysentery coincided with the seasonal prevalence of house f lies. As house flies acquired Shigella spp. from human feces in open latrines, they contaminated open food markets, hospitals, slaughter houses, and animal farm s (Levine and Levine 1991, Graczyk et al. 2001). A high density of open markets with rotting fish, meats, and vegetable matter combined with close proximity of food mark ets to slaughter houses encouraged outbreaks of house flies (Bidawid et al 1978). Incidentally, a high density of humans lacking infrastructure and garbage pi ck-up compounded the health risk s associated with house fly outbreaks (Bidawid et al 1978). In addition to Salmonella spp. and Shigella spp., house flies transmit other enteric disease organisms such as Campylobacter spp. or enterohemorrhagic E. coli which cause morbidity and mortality in humans resulting from diarrheal illnesses (Graczyk et al. 2001). Helminthic parasite s have also been transported

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3 on house fly exoskeletons and rotavirus may be transported on legs and wings, then dislodged by flight motion (Monzon et al. 1991, Tan et al. 1997). In hospitals, house flies can play a vital role as vectors of resistant strains of enteric pathogens among patients (Rady et al. 1992). Pathogens such as Klebsiella spp., Enterococcus faecalis and others have been distributed by house flies within patient wards (Graczyk et al. 2001). Many strains ar e acquired by house flie s from patients and some strains are resistant to antibiotics (Graczyk et al. 2001). Rady (1992) isolated Enterobacteriaceae, Micrococcaceae, Co rynebacteriaceae, Brucellaceae, and Pseudomonodaceae from house flies trapped in hospitals. Among the aforementioned families of bacteria, some may cause septicemia in humans (Rady et al. 1992). Although house flies primarily transport dis ease agents on their wings, tarsi, and setae, they may also spread pathogens by re gurgitation and fecal deposition (Graczyk et al. 2001). In developing countries, house flies are important vectors of Chlamydia trachomatis which causes blindness in humans (Graczyk et al. 2001). Flies carry C. trachomatis on their legs and probosces, and the agent survives in the gut for 6 hours (Graczyk et al. 2001). In laboratory studies, Helicobacter pylori was isolated from external surfaces of house flies up to 12 hour s after exposure (Gruebel et al. 1997). However, H. pylori (responsible for gastroduodenal diseas e), was also isolated from gut and excreta of house flies up to 30 hours after initia l feeding by house flies (Gruebel et al. 1997). Helicobacter organisms attached to intestinal epithelial walls of house fly guts suggested that house flies were a reservoir as well as a ve ctor (Gruebel et al. 1997). Other bacteria isolated from the di gestive tract of house flies included Klebsiella oxytoca, Enterobacter agglomerans, Burkholderia pseudomallei, Citrobacter freundii and

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4 Aeromonos hydrophila (Sulaiman et al. 2000). Yersinia pseudotuberculosis survived in the house fly digestive tract up to 36 hours af ter exposure (Zurek et al. 2001). House flies may contaminate a surface with Y. pseudotuberculosis by regurgitating their crop content (Zurek et al. 2001). Recent studies implicate house flies as vectors of Enterohemorrhagic Escherichia coli (EHEC) 0157:H7) which causes enteric hemorrh agic disease in humans. House flies acquired EHEC 0157:H7 from cow dung a nd were capable of transmitting EHEC 0157:H7 (Iwasa et al. 1999). The EHEC 0157:H7 proliferated in mouthparts of house fly where it may be ingested and disseminated by fecal deposition (Sasaki et al. 2000). Ingested EHEC 0157:H7 remained inside the cr op for 4 days and was detected in fecal drops (Sasaki et al. 2000). Biology of Musca domestica Oviposition House flies are holometabolous insects with distinct egg, larval, pupal, and adult stages (West 1951, Sacca 1964). Within 1 day of becoming gravid, adult females seek decaying organic material and animal feces for their eggs (Krafsur 1985, Hogsette 1996, Graczyk et al. 2001). Female house flies may lay 5 to 6 batches of eggs, with each batch containing 75 to 150 eggs (Hogset te 1996, Graczyk et al. 2001). Larval Development and Survival House fly larvae develop in decaying organi c material, including manure, and have three distinct larval stages (West 1951, McAl pine 1987). Larvae are milky white with a cylindrical shape that tapers anterior ly (McAlpine 1987). The posterior of M. domestica larvae is blunt and exhibits heavily scleri tized posterior spirac les (McAlpine 1987).

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5 Temperature of breeding sites directly affect s the rate of larval development (Sacca 1964, Elvin and Krafsur 1984, Lysyk 1991b, Barn ard and Geden 1993, Hogsette 1996). Developmental time from egg to adult may ra nge from 6 days under optimal temperature conditions to 50 days (Barnard and Gede n 1993). Haupt and Busvine (1968) reported that lower temperatures prol onged house-fly development and enhanced larval size. Sacca (1964) documented that 35 to 38 C was an optimal temperature range for larval development. Although higher temperature enha nced the rate of development, Barnard and Geden (1993) found that larval survival was highest between 17 C and 32 C. Moisture levels within house fly breedi ng sites affect their survival. Animal manure moisture content ranging from 50 to 70% yielded significantly more flies than drier manure (Hulley 1986, Fatchurochim et al. 1989). Fatchurochim et al. (1989) reported a significant decline in house fly surv ival in manure containing less than 40% or more than 80% moisture. In addition, Hu lley (1986) observed that manure with low moisture levels encouraged pa rasitism by pteromalid wasps. However, Hogsette (1996) found that some house flies could survive in manure containing less than 5% moisture, suggesting that house flies may survive under extreme conditions. Survival of house fly larvae is also influe nced by larval density within breeding sites. Haupt and Busvine (1968) and Barnard et al. (1998) observed inverse relationships between density and larval size and larval weight. Smaller larv ae ultimately developed into smaller pupae and adults (Barnard et al 1998). Larval mortal ity was significantly greater at high densities versus lower densit ies, while intermediate larval densities produce more viable progeny (Haupt and Busvine 1968, Bryant 1970). Bryant (1970) hypothesized that breeding sites conditioned by presence of larval densities regulated

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6 oviposition rates, and thus egg densities in natural populations ma intained an optimal density. Adult Behavior Activity and longevity Behavior and activity of a dult house flies changes with age. As male house flies age, wing function declined due to age and damage caused by mating attempts rendering them flightless within 12 days (Ragland and Sohal 1973). Mating activity, like flight activity, also declined with age. Flight activity of M. domestica may be influenced by temperature and age. House flies are mobile between 14 and 40 C but peak flight activity occurs between 20 and 30 C (Tsutsumi 1968, Luvchiev et al. 1985). Flight activity signi ficantly decreased above 35 C and activity ceased above and below 20 C, but high relative humidity contributed to a 2to 3-fold increase in f light activity (Tsutsumi 1968, Buchan and Sohal 1981, Luvchiev et al. 1985). Since higher temperatures induced greater house fly activity, Buchan and Moreton (1981) observe d that house fly lifespan significantly decreased at higher temperatures. They hypothe sized that higher temperatures induced a higher metabolism, suggesting that the house fl y rate of living also increased (Buchan and Moreton 1981, Buchan and Sohal 1981). Later experiments confirmed that life expectancy of both sexes significantly declin ed as temperature increased from 20 to 35 C (Fletcher et al. 1990, Lysyk 1991a). Population density may also influence longe vity of adult house flies. The life expectancy in the lab may range between 12 and 30 days for adult male house flies and between 11 and 44 days for adult females (Rag land and Sohal 1973, Fletcher et al. 1990).

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7 Caged experiments using adult house flies show ed an inverse relati onship between adult life expectancy and population density (Rockste in et al. 1981). Susceptibility to high mortality associated with high density was greater for males than females (Haupt and Busvine 1968). Field experiments using ar tificial garbage dumps showed exponential growth of fly populations within 1 month of dumping the garbage and confirmed that as density increases, survivabil ity decreases (Imai 1984, Krafsur 1985). Both adult males and females also showed an inverse relations hip between life expectancy and mate access (Ragland and Sohal 1973). Dietary restrictions may al so influence life expectancy and activity of adult house flies. Rockstein et al. (1981) reporte d that protein-starved hous e flies of both sexes had a significantly lower life expectancy than prot ein-satiated flies. Adding sucrose for house flies reared on manure or powdered milk si gnificantly increased the longevity of both sexes (Lysyk 1991a). Starved flies and flie s fed on sugar-only diet s were significantly more active than protein-satiated hous e flies (Tsutsumi 1968, Skovmand and Mourier 1986). Conversely, replete flies rested and s howed a significantly higher frequency of regurgitation and resting behaviors (Tsutsumi 1968). Photoperiod House flies are diurnal insect s whose activity is directly related to light intensity (Tsutsumi 1968, Sucharit and Tumrasvin 1981). Adult house flies entrained on a 12:12 (L:D) photoperiod showed resting behavior induced by lower light levels, and ceased flight activity at the onset of night even when the photoperiod was removed (Tsutsumi 1968). Although peak activity times ranged fr om 9AM to 4PM, continuous brightness ultimately suppressed the circadian rhythm of the house fly and complete darkness inhibited house fly activity (Tsutsumi 1968, Meyer et al. 197 8, Semakula et al. 1989).

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8 Dispersal House flies are disease vectors capable of dispersing between 5 and 20 miles from their point of origin (Schoof and Silverly 1954b, Morris and Hansen 1966). Initial markrecapture studies showed that flies dispersed randomly and approximately 50% of 150,000 released flies were captured within mile from their initial release point (Schoof and Silverly 1954b). It was estimated that flies migrate 0.5 miles to 2.5 miles over a period of 1-5 days (Morris and Hans en 1966). However, a lack of available breeding sites encouraged flies to disperse up to mile within 3 to 8 hours (Pickens et al. 1967). Although dispersal was random, Pickens et al. (1967) observed house flies were 2 to 3 times more likely to disperse from cl ean dairy farms versus unsanitary farms with multiple breeding sites. Environmental factors such as wind may al so affect dispersal (Morris and Hansen 1966). Strong down winds may aid in disper sal, but house flies have been observed flying upwind of breezes between 2 and 7 m ph (Morris and Hansen 1966, Pickens et al. 1967). In poultry and dairy units containing great abundance of animal manure, house flies dispersed approximately 50 meters (Lysyk and Axtell 1986, Hogsette et al. 1993) Rather than density-depende nt mortality in field studies, evidence shows densitydependent dispersal toward better habitat (Imai 1984, Krafsur 1985). However, studies in poultry houses showed house fly distribution downwind was twice as great as upwind with dead-air zones containing the greatest a bundance of adults (Geden et al. 1999).

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9 Attractants for Musca domestica Chemical Attractants House flies respond to a wide variety of ch emical or odorous attr actants. In initial studies, excrement and decomposing organic material attracted si gnificant numbers of house flies into containment traps (West 1951, Mulla et al. 1977). Food baits composed of sugar, molasses, putrifie d egg extracts, or chicken a nd rice were also successful attractants or served as a me dium for insecticides (Pickens et al. 1973, Mulla et al. 1977, Pickens et al. 1994, Pickens 1995). Other stud ies using an odorous “dumpster recipe” caught significant numbers of house and stable fl ies, but such attractants may be limited to the outdoors (Pickens et al. 1975, Rutz et al. 1988). The discovery and synthesis of the female sex pheromone (Z)-9-tricosene led to the development of muscalure and enhanced the e fficacy of synthetic fly baits (Carlson and Beroza 1973, Carlson et al. 1974). Although (Z )-9-tricosene is produced by females, field trials showed significant attraction of both male and female house flies (Pickens et al. 1975, Rutz et al. 1988, Chapman et al. 1999). High concentration of (Z)-9-tricosene many act as an aggregation pheromone for both sexes of M. domestica (Chapman et al. 1998). Physical Attractants Color House flies respond to a variety of envir onmental factors such as color, light quality, light reflectance, and color contrast (Hecht 1970). High color saturation of a surface combined with a strong contrast between that surface and its surrounding environment was thought to be more attractive to M. domestica than individual colors, however their response to individual colors s eemed to change with temperature (Pickens

PAGE 21

10 et al. 1969, Hecht 1970, Green 1984, Bellingham 1995, Snell 1998). Although Hecht (1970) detected no significant differences in house fly response to black and white surfaces across temperatures ranging from 15 to 40 C, he also did not measure the quality of reflected light. The spectrum of reflected light, regardless of surface color, is more likely to induce landing response by house flies than the color of the surface (Bellingham 1995). Surfaces that reflected UV were more attrac tive to stable flies, while surfaces that absorbed UV were more attractive to horse flies (Agee et al. 1983, Hribar et al. 1991). Colorimetric studies with the face fly, Musca autumnalis suggested that edge effects of baited traps could be enhanced by maximizi ng color contrast between traps and the surrounding environment (Pickens 1990). Surfaces Plane geometric patterns or shapes displayed on a surface may also enhance landing-response by M. domestica Single shapes consisting of a large area and perimeter were significantly more attractive than a seri es of small shapes with small perimeters (Bellingham 1995). When house flies were pres ented with a series layout of squares, they significantly preferred outer squares and edges versus inner squares, with both sexes exhibiting significant preference towa rd shape corners (Bellingham 1995). There were no significant preferences by house flies towa rd symmetric versus asymmetric shapes, but simple shapes such as triangles and rect angles were significantly more attractive to house flies than complex shapes such as hexagons and octagons (Bellingham 1995). Bellingham (1995) and Hecht (1970) observed th at house flies preferred to rest on rough dark surfaces such as red and black and pref erred matte surfaces over glossy surfaces.

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11 Overall, house flies preferred to rest on corners and edges of shapes or objects as well as narrow vertical objects hanging from ceiling, but they exhibited no significant preference toward horizontal or vertical stripes on a glue board (Keiding 1965, Bellingham 1995, Chapman et al. 1999). Later experiments on landing response demonstrated that house flies significantly preferred a clumped distri bution of small black spots against a white background versus a regular distribution of spots (Chapman et al. 1998, Chapman et al. 1999). These studies suggested that visual cues resembling house-fly aggregations may also induce landing response (Chapman et al. 1999). Light The house fly eye is composed of differen t cells that are cap able of gathering information about light quantity, qualit y, and polarization wi thin the surrounding environment. Each facet of the compound eye of M. domestica contains three different kinds of photocells designated as R1 – R 6, R7, and R8 (McCann and Arnett 1972). Each cell type provides specific visual informa tion to the insect (McCann and Arnett 1972). Cells R1R6 + R7 contain photopigments se nsitive to 350-nm and 490-nm peaks with R8 containing photopigment sensitive to 490 only (McCann and Arnett 1972, Bellingham 1995). The dorsal rim area of the house fly eye detects polariza tion and polarization sensitivity is located in the R7 and R8 marginal cells (Phili psborn and Labhart 1990). Philipsborn and Labhart (1990) determined th at house fly attraction to polarized light, especially in the UV range, is directly relate d to intensity of light. However, polarized UV did not always elicit photot actic response from house flie s (Philipsborn and Labhart 1990). Polarization sensitivity is thought to provide information on spatial forms, motions, velocity, and contrast ratio in the fly’s environment and thus may help the fly track mates (McCann and Ar nett 1972, Bellingham 1995).

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12 The visible spectrum for M. domestica ranges 310 nm – 630 nm, with optimal attraction observed at 350 nm (Thimi jan and Pickens 1973, Bellingham 1995). Electroretinogram studies have shown that the M. domestica eye is sensitive to UV light ranging from 340 nm to 370 nm and blue-green light ranging from 480 nm to 510 nm, but there is debate over how this sensit ivity affects optomotor response of M. domstica (Goldsmith and Fernandez 1968, McCann and Arnett 1972, Thimijan and Pickens 1973). Goldsmith and Fernandez (1968) observed positive phototaxis by M. domestica towards UV light of 365 nm. McCann a nd Arnett (1972) observed that M. domestica is equally sensitive to 350 nm UV and 480 nm blue-g reen and concluded the house-fly eye contained separate photopigments for UV and blue-green light sensitivity. Similar studies with the face fly, Musca autumnalis revealed a similar spectral range from 350 nm to 625 nm with peak sensitivities at 360 nm and 490 nm (Agee and Patterson 1983). Although blue-green sensitiv ity was relatively high, M. domestica attraction gradually decreased from 390 nm to 630 nm with no si gnificant differences between male and female responses (Thimijan and Pickens 1973). Further studies have shown the house fly eye contains more UV-sensitive pigments in its dorsal region (B ellingham 1995). It was hypothesized that sensitivity to UV and blue gr een light may allow the fly to distinguish between ground and sky and detect predators or mates against the sky (Bellingham 1995). Green and red light wavelengths may induce negative phototaxis in M. domestica (Green 1984). Green (1984) observed a di rect relationship between attraction and intensity of near-UV 400-nm light and an inverse relationship between attraction and intensity of 550-nm (green) light. Stra ight UV elicited a significantly stronger phototactic response from M. domestica than green-UV suggesti ng that green-UV is less

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13 attractive to house flies (Green 1984). Musca domestica were unable to distinguish red lights from green lights at various intens ities (Green 1984). Be llingham (1995) observed that house flies detected red light (630 nm ) but sensitivity to re d was not attraction. Female house flies were more sensitive to re d than males with th e dorsal region of the eye containing red-sensitive pigments (Bellingham 1995). Control Using Attractants Chemical Baits Insecticidal food baits or c ontainment traps rely on synt hetic attractants such as muscalure ((Z)-9-tricosene) to attract house flies and provide localized control of house fly populations. High doses of muscalure mixe d with a sugar bait attracted significant numbers of house flies and seemed to pr omote significantly higher consumption of insecticide baits (Morgan et al. 1974, Lemke et al. 1990). Newer technology incorporating polymer beads impregnated with (Z)-9-tricosene significantly enhanced the long-term efficacy of sugar baits (Chapman et al. 1998). Physical traps combining muscalure with visual cues caught signifi cantly more house flies than traps without muscalure (Mitchell et al. 1975, Mu lla et al. 1979). However, baited trap catch decreased significantly at lower temperatur es due to decreased volatiliza tion of attractants (Pickens and Miller 1987). Physical Traps Baited jug traps made from plastic milk j ugs, utilized (Z)-9-tricosene and indole to capture house flies breeding in poultry units (Burg and Axtell 1984). Although this design killed thousands of house flies, jug tr aps are primarily used for monitoring house fly populations (Burg and Axtell 1984, Stafford III et al. 1988).

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14 Pickens and Miller (1987) re ported that pyramid traps, utilizing glue boards or electric grids, were effectiv e at intercepting dispersing hous e flies before they entered buildings (Pickens and Miller 1987). Subse quent trials with pyramid traps determined that vertical orientation of electric grids combined with chrome plating on electronic grids attracted and killed significantly mo re house flies (Pickens and Mills 1993). Replacing paint with white plastic increased UV reflectance, and thus attracted significantly more house flies toward pyramid traps (Pickens and Mills 1993). Success of physical traps is largely depe ndent on their proximity to house fly breeding sites. Baited jug traps were most effective when hung 1 m above breeding and aggregation sites (Burg and Ax tell 1984). Pyramid and baited traps were significantly more effective when placed within 3 m of br eeding sites or sheltered from wind (Pickens and Miller 1987). Insect Light Traps (ILT) Insect light traps (ILTs) and electronic fl y killers (EFKs) uti lize UV light to lure M. domestica onto glue boards or kill them with electricity. Su ch devices are designed to exploit positive phototaxis in house flies a nd remove them from environments where insecticide applications ar e not an option. However, house fly response to UV traps varies due to a range of environmen tal and physiological factors. House Fly Response to ILTs Age of M. domestica may influence their response to light traps. Adult male and female house flies aged 7 d or older exhibite d significantly slower response to UV light traps than flies aged 1 to 5 days (Picke ns et al. 1969, Skovmand and Mourier 1986). Deimel and Kral (1992) observe d that light sensitivity wa s related to age-dependent concentration of the photopigment xanthopsin in cells R1-R6. Age-dependent sensitivity

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15 to light may have been influenced by visual experience gained within the first five days after adult emergence (Deimel and Kral 1992). Hunger and nutrition also influe nced searching activity of M. domestica, and thus light-trap catch may also be affected (S kovmand and Mourier 1986). House flies that were starved or sustained on a sugar and wate r diet were significantly more active than protein-satiated flies and thus starved flies responded to UV-light traps in significantly less time than protein-satiated flies (S kovmand and Mourier 1986). Bellingham (1995) suggested that food searching is non-oriented behavior motivat ed by the insectÂ’s intrinsic nutritional needs. Once the insect satiates its hun ger, then its behavior shifts toward mate location and environmental orientation (Bel lingham 1995). This reasoning suggests that starved house flies are not necessarily more attr acted to UV-light traps than satiated flies, but rather they have a higher probability of being caught simply because they are more active. Design and Location of ILTs Further attempts to enhance ILT perfor mance focused on trap designs included increasing bulb wattage, manipulating trap colo rs, and adding reflective surfaces to the trap exterior. Increased bulb wattage provi ded a higher intensity of UV light, and thus yielded a significant increase in catch, but the use of black light blue (BLB) bulbs did not significantly increase attraction of house or stable flies when compared to standard black light (BL) bulbs (Pickens 1989b, Snell 1998). Pickens and Thimijan (1986) suggested a black-box trap offered greatest contrast to UV bulbs and caught significantly more flies. However, Snell (1998) found that black backgr ound was significantly less attractive than white background. Snell (1998) also suggested that grills created a significant distraction for house flies by providing them with a place to rest. Traps with grea ter grill lengths in

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16 front of the UV bulbs caught significantly fewe r flies compared with traps that had lower grill length (Snell 1998). Location of light traps also plays an important role in their efficacy. Studies with electronic fly killers (EFKs) in poultry units demonstrated that traps located within 1m of the ground eliminated significantly more house flies than traps located 2m or higher (Driggers 1971). Subsequent studies with baited pheromone traps also reinforced the idea that ground-level traps within 3m of breeding sites were most efficient for eliminating flies (Mitchell et al 1975, Pickens and Miller 1987). Skovmand and Mourier (1986) acknowledged that competing light so urces as well as competing attractants distracted a significant number of house flies away from EFKs. They concluded UVlight traps, specifically EFKs, only provided ma rginal control in swine units because the abundance and production of house flies exceed ed the trapsÂ’ ability to recruit flies (Skovmand and Mourier 1986). Competing Light Sources The urban environment presents house f lies with location challenges as well as artificial light sources that may interfere with UV light traps. Lill ie and Goddard (1987) demonstrated that multiple light traps si gnificantly reduced house fly populations in restaurant kitchens. However, traps visibl e to the outdoors may a ttract flies into the structure (Lillie and Goddard 1987). Additionally, placement of light traps in dim areas enhanced the catch of house flies (Picke ns and Thimijan 1986). Both Pickens and Thimijan (1986) and Shields (1989) implied that artificial cool-white fluorescent light adversely affected house-fly attraction to UV light traps, but neither study examined intensity or quality of artificial light.

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17 Although greater light intensity may attract more flies, othe r factors such as flicker fusion and directionality of light may influe nce house fly response to a light source. Syms and Goodman (1987) disc overed that light flicker cr eated by alternating current (AC) was more attractive to hous e flies than light produced by direct current (DC). Ultra violet lights from AC sources with half the intensity of DC sources caught significantly more house flies (Syms and Goodman 1987, Shie lds 1989). Additionally, diffuse sources of light were significan tly more attractive to M. domestica than directiona l light (Roberts et al. 1992). Neither Syms and Goodman ( 1987) nor Roberts et al. (1992) found any sexrelated differences in house-fly response to AC-flicker or diffuse light sources. The effects of competing light sources on vector monitoring programs utilizing light traps have been documented in th e mosquito literature. Bowden (1973) acknowledged the inverse relationship between mo squito catch in light traps and intensity of background illumination from the moon. The intensity of moonlight gradually changed with each phase, light trap catches of mosquitoes adjusted accordingly (Bowden 1973). In Venezuela, illumination from a fu ll moon reduced light trap catch abundance of Anopheles spp. by approximately one-half when compared to moonless trap nights (Rubio-Palis 1992). Similarly in India, Singh et al. (1996) documented significant reduction of Anopheles spp. caught by Center for Dis ease Control (CDC) light traps during a full moon phase compared with moonl ess trap nights. A lthough total catch was significantly lower, the parity rates of Anopheles spp. among samples remained the same regardless of the moon phase (R ubio-Palis 1992, Singh et al. 1996). Bowden (1973) documented an inverse re lationship between m oonlight and trap catch for a variety of species of Coleopter a and Lepidoptera. Si nce light intensity

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18 decreases at a rate equal to the inverse square of distance from its source, Bowden (1973) asserted that light traps exerte d a region of influence unique to individual species and that insects outside of this region of influence would remain unaffected by the light trap. Therefore, modifications to light trap output or the intensity of competing illumination would alter a light trapÂ’s ar ea of influence (Bowden and Church 1973, Bowden 1982). In subsequent studies, Bowden (1982) estim ated a minimum 12:1 ratio of background luminosity to trap luminosity was necessary to have an adverse effect on light trap performance. Increasing UV output from light traps may overcome some of these obstacles, but Bowden (1982) also noted a curvilinear relations hip between total UV output and trap catch where significant increas es in UV output resulte d in marginal or no increases in trap catch (Bowde n 1982). It is not known if th e same relationship exists for house flies. Statement of Purpose The purpose of my research is to underst and how factors in urban environments affect the catch efficacy of UV light traps used to manage house flies. I have designed a light-tunnel bioassay that presen ts house flies with both a UV light trap and a source of overhead competing light. Since location of UV traps may influence catch, the first research chapter (Chapter 2) establishes a baseline study of a li ght-tunnel bioassay that does not exhibit location bias. This bioassay was then used to determine effects of house fly age and gender on trap catch. The time to catch 50% of a population (CT50) was estimated for house flies to determine the approximate time house flies responded to a UV trap. Information from these studies helped to eliminate any bias and determine the proper age range of house flies and lengt h of time for the experiments.

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19 Chapter 3 explores how intensity and spect rum of competing light sources affects house fly response to UV light trap s. Light intensities sample d in five local restaurants and grocery stores provided a ba seline range of intensity treatments for my experiments. For light quality experiments, house flies we re presented with competing lights with spectral outputs ranging from UV light up through warm-white fluorescent. Finally, Chapter 4 explores whether conti nuous exposure to artificial light induces habituation or attraction. If house flies habituate to light after continuous exposure, then I hypothesize that they would be less attracted to that source of light over time.

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20 CHAPTER 2 ESTIMATES OF RESPONSE TIME BY HOUSE FLIES TOWARD UV LIGHT TRAPS USING LIGH T-TUNNEL BIOASSAY Introduction The house fly, Musca domestica L., is a synanthropic filth fly that breeds in garbage and animal waste (Schoof and Silverly 1954a, Greenberg 1973, Imai 1984, Graczyk et al. 2001). Larvae develop in manure, and the adults will feed on the larval substrate (Hogsette 1995). Growing populations of adult house flies are a nuisance to livestock, poultry, and humans especially in urban centers adjacent to farming communities (Hogsette and Farkas 2000). In addition, house flies may also transmit enteric pathogens such as Shigella spp. and Salmonella spp., which they may acquire from their breeding sites and transmit to humans (Levine and Levine 1991, Graczyk et al. 2001) The significance of house flies as disease ve ctors is enhanced by their capability of dispersing approximately 30 km from their poi nt of origin (Schoof and Silverly 1954b, Morris and Hansen 1966). Subsequent studies estimated that flies dispersed an average of 1 to 4 km over a period of 1 to 5 d in s earch of suitable breeding sites within rural or urban areas (Morris and Hansen 1966, Hogsette and Farkas 2000). As house flies cause problems in structures, light traps were deve loped as a tool to intercept house flies by attracting them to UV light and killing them with glue boards or high-voltage electricity (Pickens et al. 1969, Bowden 1982, Roberts et al. 1992). Prompt removal of house flies within hospitals, gro cery stores, or restaurants is necessary to

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21 prevent transmission of diseases among pe ople and food sources (Levine and Levine 1991, Rady et al. 1992, Graczyk et al. 2001). Insect light traps are used to attract and catch house flie s, but factors such as fly age or trap location within a building may lim it trap catch. Dispersal from breeding sites into structures may take days, and as flies di sperse, they age and may exhibit a significant decline in flight activity (Ragland and Sohal 1973). As house flies en ter structures, light traps obscured from view may have little or no effect on a house-fly infestation and significant wind or air movement within a building may redirect house flies downwind away from potential light tr aps (Lillie and Goddard 1987, Rutz et al. 1988, Geden et al. 1999). Additionally, incident light from window s or overhead fixtures may also be an additional source of variability for light tr ap studies (Pickens and Thimijan 1986, Syms and Goodman 1987). Although previous studies sought to understa nd variables that ma y affect light-trap performance, none have provided a standardized bioassay that elimin ates variables such as background light, trap location, or air move ment within a structur e. Therefore, the first objective of this study was to develop and standardi ze a procedure that overcomes effects associated with light-trap placem ent. The second objective was to use the standardized procedure to examine the effect s of fly age on light-trap catch efficacy and to examine house fly response time to insect light traps. Materials and Methods Insects. Two strains of M. domestica were used in this research; the USDACMAVE strain and the Horse-Teaching-Unit (H TU) strain, both from Gainesville, FL. Larvae from USDA-CMAVE strain were reared on USDA larval medium and held on a 12:12 (L: D) photoperiod (Hogsette 1992). Larvae from the HTU strain were reared on a

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22 medium containing 3 liters wheat bran, 1.5 liters water, and 250 ml of Calf Manna (Manna Pro Corp., St. Louis, MO) pellets. All stages of HTU strain were placed on a 12:12 (L: D) photoperiod at 26 1 C and 51.03 3.49% RH. Adult flies from both strains were provided granulated sugar, powdered milk, and water ad libitum and held on a 12:12 photoperiod (L:D) (Hogsette et al. 2002). Adult flies were he ld no longer than 7 days. Before experimentation, adult flies between 2 and 5 d of age were aspirated from screen cages (25.4 by 53.3 by 26.7 cm) using a ha ndheld vacuum with modified crevice tool. Aspirated flies were transferred into a refrigerator (~5 C) for 2 min to subdue activity. Flies were removed from the refriger ator and placed on a chilled aluminum tray, counted and sexed. Counted and sexed flies we re placed into plastic cups (237 ml), lids were placed over the cups, then the flie s were held at room temperature for approximately 30 min before being placed into experiments. All flies were handled with camel hair paint brushes a nd featherweight forceps. Light tunnel design. The enclosed light-tunnel (152 by 20 dia. cm metal duct) consisted of a release cage attached to a galv anized aluminum light tunnel that terminated in a box enclosing a light trap (Fig. 2-1). The release cage (30 by 30 by 45 cm) was fitted with a sheet-metal bottom and aluminum windo w screen on the top, sides, and one end. Stockinette was fitted on the remaining end (30 by 30 cm) to allow access into the cage. Release cages were placed on a 10.4 cm-high pl atform to make them level with a light tunnel entrance. The light tunnel (152 by 20 dia. cm metal duct) was painted with one coat of primer and one coat of flat black pain t, then allowed to cure for at least 3 d to eliminate paint fumes. A light-tunnel en trance (20 cm dia.) was cut into the box

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23 enclosure (66 by 91 by 60 cm) which was constr ucted of corrugated cardboard. The 20 cm hole was centered horizontally on the 91cm face and was 12.7 cm from ground level. Vents were cut in the top of the box encl osure (17.7 by 38.1 cm) to prevent buildup of heat from light traps. A piece of black orga ndy was glued over each vent to prevent flies from escaping. A piece of plywood (91 by 60 cm) was painted with white paint and placed inside the box enclosure opposite the light tunnel entrance. One UV light trap (Nova, Whitmire Microgen Inc., St. Louis, MO) was mounted with four screws onto the white plywood inside the box enclosure. Th e trap was laterally centered and located directly opposite the light tunnel entrance. The trap utilized three 15-watt UV bulbs (Sylvania Quantum Manchester, UK) as well as a horizontal (7.6 by 40.6 cm) and a vertical glue board (25.4 by 40.6 cm ). Ultra-violet (UV) bulbs in traps had < 1000 h use. A workshop fixture containing two 40-watt Sylvania cool-white fluorescent light bulbs was hung 8 cm above top of release cages to pr ovide a source of background light that is common in urban environments. The distance of 8 cm above the cages was selected in order to establish intensity comparable w ith levels of compe ting light in urban environments. Procedure. To perform an experiment, new gl ue boards were placed inside traps and all lights were turned on. One hundred sexe d flies were released from a plastic cup (237 ml) into a release cage. Experiments commenced when stockinette on the release cages was unfurled and wrapped around the en trance of the light tunnel, allowing flies access to the UV light trap. At the end of each experiment, the release cages were sealed and removed, traps turned off, and glue boa rds collected. Flies not captured were

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24 removed from the experimental set up pr ior to subsequent repetitions. Ambient temperature for all experiments was approximately 29 C. Quality and quantity of background light and ultraviolet light were measured at the release-cage end of the li ght tunnel with a USB2000 Spectrometer (Ocean Optics, Dunedin, FL) (Fig.2-2). Absolute light quant ity from cool-white fluorescent light and UV-trap output was measured with a HOBO Light Intensity logger (Onset, Bourne, MA). Intensity data from light tr aps and overhead fluorescent lig ht were analyzed at each position to investigate significant differences among the light sources. Separate one-way analyses of variance were run using light intensity as the re sponse variable against trap and position within building as main factors. Location dependent assay. Experiments were conducted in two buildings (3 by 3 m) designated as Buildings A and B. All windows were covered with aluminum foil to prevent external light from interfering with experiments. Two positions were identified within each building and designated as positions a1 and a2 for Building A and positions b1 and b2 for Building B. The four box en closures opposite the release cages were consecutively numbered and rotated among all four possible positions nested within the two buildings. All repetitions used house flies from both strain s. Four replications, each with 100 adult house flies (50 M: 50 F) aged 2 to 5 d, were conducted per box and position, for a total of eight replications per bu ilding. Assays were concluded after 4 h. Age dependent assay. Pupae from both strains were removed from larval medium and placed in separate screen cages (40.6 by 26.7 by 26.7 cm). Flies were allowed to emerge for 24 h, then pupae were removed to en sure that all flies were of the same age.

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25 Age of flies was based on the number of days after adult emergence from pupal cases. The assay was conducted with 100 flies (50 M: 50 F) aged 1, 3, 5, or 7 d placed in the release cage and left for 4 h. Flies on glue boards were counted sexed. Four replications per age were conducted. Time dependent assay. Time treatments were started simultaneously when 100 adult flies (50 M: 50 F) were pl aced into each of four separa te release cages for 1, 2, 4, or 8 h Treatments were randomly assigned to each release cage a priori with four replications per time. At the end of e ach time period, the assigned release cage was closed, glue boards were collected, and the light trap was turned off. Statistical analysis. For location studies, total numbers of male and female flies caught on glue boards were analyzed using a tw o-way nested analysis of variance with box enclosure and building as fixed factors with position nested within the building. Time and age studies were separately analy zed with one-way analysis of variance with time (h) or age (d) as fixed factors. M eans separation for significant F-values was performed with a Student-New man Keuls (SNK) test. A catch time for 50, 90, and 95% of house flies (CT50) caught by UV light traps was estim ated using probit analysis (SAS 2001). Results and Discussion Location Dependent Assay. Analyses of spectrometry data indicated there were no significant differences in lig ht spectra and intensity from UV light traps (F=0.29; df = 3, 298; P = 0.83) or overhead cool-white fluor escent light among the four set ups (F=2.22; df = 3, 325; P = 0.085) (Figures 2-2 and 2-3) There were no significant differences in the numbers of house flies ca ught among the locations within buildings A and B (F = 0.89; df = 3, 13; P = 0.46) nor were any significa nt differences detected

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26 among the four box enclosures (F=0.22; df = 3, 13; P = 0.87) (Table 2-1). On average, 65 adult house flies were caught among all positions over a period of 4 h, thus the different positions within and among buildings A and B did not signi ficantly influence house fly response to light traps (Table 2-1). In previous studies, the effects of location bias on catch efficacy of UV light traps depend largely on environmental factors unique to each site. Lillie and Goddard (1987) found that catch efficacy in urban environments varied due to trap location relative to other sources of light such as windows or doors that might lure flies away from a UV light trap. Light quality and intensity were standardized in this research among all positions within our buildings. Rutz et al. (1988) suggested that UV light traps are most effective when placed in close proximity to house-fly breeding sites and areas of high activity, but they did no t define any specific distance. In the current study, house flies were released 2.66 m from the UV light traps. Furthermore, Geden et al. (1999) reported that in closed poultry units, house flies signi ficantly preferred dead -air spaces versus direct air currents. By providing an en closed light-tunnel design, the current study eliminated air movement between the rele ase cage and the light trap. Thus, results showed that removing variability of locati on, trap distance, background light intensity, and air movement, assured that the house f lies responded to light traps in consistent manner. Age-dependent assay. Significantly greater numbers of male house flies aged 1, 3, and 5 d were caught by UV light traps than 7day old male house flies (Table 2-2). One possible reason for this decline is that as male house flies ag e, wing function declined due to damage caused by mating attempts (Ragland and Sohal 1973). Within our colonies, I

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27 observed mating attempts among flies of all ages but noticed significant wing damage among males aged 7 d or older. There was no significant difference in response among all age groups of female house flies toward UV light traps (Table 2-2) The nutritional state of 7 d old female house flies may have influenced their activity le vels. All house flies had access to protein (powdered milk), carbohydrates (granulated sugar), and water within 1 h prior to experiments. Tsutsumi (1968) reported that pr otein-satiated house flies rest more and fly less than protein-starved house flies. However, if protei n-satiated adult females were mated, then their flight activity may have in creased as they searched for a site for oviposition (Tsutsumi 1968, Skovmand and Mourie r 1986). If females were gravid and looking for a dark place to oviposit, then one would expect to see a decline in their response towards light traps. When results of both sexes were combine d, the overall response to UV light traps by adult house flies significantly decreased at 7 d of age because of the reduction in the number of males captured (Table 2-2). Resu lts agree with previous studies indicating that significantly fewer house flies aged > 5 d were caught in UV light traps (Pickens et al. 1969). As house flies age, their sensitivity to light decreases due to deterioration of photopigments within cells R1-R6 of the fly eye (Deimel and Kral 1992). These results confirmed that house flies aged 5 d are most likely to be caught in UV light traps. Time-dependent assay. The cumulative mean number of male and female house flies caught by UV light traps significantly increa sed over a time period of 1 to 8 h (Table 2-3). Although total trap catch by 8 h was significantly greate r than catch at 4, 2, or 1 h,

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28 some house flies did not respond to the light trap and remained in the release cage throughout the duration of the e xperiment (Table 2-3). Male house flies were caught inside th e light traps within an estimated CT50 of 1.56 h (99 min) (Table 2-4). The CT90 and CT95 estimated catch time for males at 5.03 h (301.8 min) and 7.01 h (420.6 min), respectively (Table 2-4). Female house flies were caught inside the light trap s within an estimated CT50 of 1.90 h (114 min) (Table 2-4). The CT90 and CT95 estimated catch time for females at 7.02 h (421.2 min) and 10.17 h (610.2 min) respectively (Table 2-4). Probit analysis estimated the CT50 for total house fly response toward an UV light trap at approximately 1.72 h (103.2 min) (Table 2-4). The CT90 and CT95 estimate for total house fly catch was 6.01 h (360.6 min) a nd 8.57 h (514.2 min), respectively (Table 2-4). There was no significant difference be tween male and female response time as evident by overlapping 95% confidence intervals for CT50, CT90, and CT95 (Table 2-4). Skovmand and Mourier (1986), who also conducted a series of light-trap experiments inside an enclosed chamber, concluded that male house flies responded to UV light traps in significantly le ss time than females. The CT50 estimate of 99 min (1.56 h) for male response was similar to their estimated LT50 of 100 min (Skovmand and Mourier 1986). However, the CT50 estimates for females of 114 min was slower than the 52 min reported by Skovmand and Mourier (1986), and there were no significant differences in response time between males and females (Table 2-4). During these studies, I observed some house flies remain ed inside the rele ase cage throughout the duration of the test and thus, reduced our esti mates for house fly response to light traps.

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29 In conclusion, the light-tunnel bioassay enabled us to standardize conditions for age and time studies by reducing variability associat ed with air movement, trap location, trap distance, and background light House flies that were 5 d old exhibited significantly greater attraction toward UV light traps than older flies. Estimates of CT50 by house flies toward UV traps ranged from 99 to 114 min for males and females, respectively, with no significant difference in response between the sexes.

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30Table 2-1. Effect of building, position w ithin building, and box enclosure on the num ber of house flies caught in UV light tra ps (50 M: 50 F per repetition). Building Mean SE Position Mean SE Box enclosure Mean SE A 63.56 2.41 a1 63.75 3.79 1 65.62 3.56 B 68.00 2.58 a2 64.87 3.63 2 65.62 3.71 b1 68.37 3.72 3 68.00 3.51 b2 68.12 3.71 4 65.87 4.25 Means within a column followed by the same letter are not si gnificantly different (P = 0.05, Stude nt Newman-Keuls test [SAS Institute, 2001]).

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31Table 2-2. Influence of age and sex on number of house flies caught in UV li ght traps (50 M: 50 F per repetition) Fly age (d) 1 3 5 7 Gender Mean SE Mean SE Mean SE Mean SE Male 40.75 2.33a 38.25 1.47a 45.5 1.97a 22.75 3.22b Female 46.25 2.18a 48.25 3.75a 42.5 2.52a 40.00 1.08a Total 87.0 3.21a 87.25 3.37a 88.0 2.67a 62.6 4.21b Means within a row followed by the same letter are not significantly different (P = 0.05, Student Ne wman-Keuls test [SAS Instit ute, 2001]).

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32Table 2-3. Cumulative house-fly ca tch in UV light traps over time (50 M: 50 F per repetition) Time (h) 1 2 4 8 Gender Mean SE Mean SE Mean SE Mean SE Male 15.2 1.88a 31.0 1.92b 37.0 2.24b 48.0 1.3c Female 12.6 1.03a 26.8 3.76b 32.8 3.92c 45.8 1.46d Total 27.8 2.6a 57.8 5.32b 71.8 6.58c 93.8 2.03d Means within a row followed by the same letter are not significantly different (P = 0.05, Student Ne wman-Keuls test [SAS Instit ute, 2001]).

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33Table 2-4. Estimated time (h) to catch of adult house flies by UV light traps using Probit analysis n Reps Slope SE CT50 95% C. I. CT90 95% C. I. CT95 95% C. I. X2 P Male 50 5 2.52 0.18 1.56 1.40-1.72 5.03 4.29-6.15 7.01 5.78-9.01 0.34 0.557 Female 50 5 2.26 0.15 1.90 1.71-2.11 7.02 5.88-8.80 10.17 8.19-13.43 0.52 0.467 Total 100 5 2.35 0.11 1.72 0.59-1.84 6.01 5.31-6.95 8.57 7.37-10.26 1.03 0.307

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Figure 2-1. Light tunnel design illustrating release cage (30 by 30 by 45 cm) (foreground), overhead light source ( 101.6 cm), light tunnel (152 by 20 cm), and box enclosure (66 by 91 by 60 cm) containing light trap Box Enclosure Light Tunnel Release Cage Overhead Light Source Platform

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35 Figure 2-2. Intensity (lumens / m2) of UV-light trap with re lative intensity of light by wavelength Intensity SE of UV light traps 1.33 0.048 lumens/m2

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36 Figure 2-3. Intensity (lumens/m2) of cool-white fluorescent light with relative intensity of light by wavelength Intensity SE of cool white fluorescent light 54.87 0.92 lumens/m2

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37 CHAPTER 3 INFLUENCES OF QUALITY AND INTENSITY OF BACKGROUND LIGHT ON HOUSE FLY RESPONSE TO LIGHT TRAPS Introduction Musca domestica L. is a synanthropic insect that breeds in animal waste, dumpsters, and garbage (Morris and Hans en 1966, Imai 1984). They are known to transmit pathogens such as Salmonella spp., Shigella spp., Campylobacter spp., and enterohemorrhagic E. coli from their breeding sites to open food markets, hospitals, slaughter houses, and animal farms (Levin e and Levine 1991, Iwasa et al. 1999, Graczyk et al. 2001). Because house flies are potenti al disease vectors, their control in urban environments is necessary to prevent food contamination. A variety of devices have been devel oped to attract and kill house flies in agricultural and urban areas. Baited trap s containing molasses, sugar, decomposing biomass, or animal excrement have been used to lure house flies in to a catch basin from which they can not escape (West 1951, Pickens et al. 1973, Mulla et al. 1977). Pyramid traps utilizing glue boards or electrocution grids were effect ive at intercepting house flies before they entered buildings (Pickens a nd Miller 1987). But although these traps may be effective in outdoor settings, their odorous baits and visibility prohibit their use indoors. Additionally, trapped flies must be emptied and baits must be replenished to maintain trap efficacy. Insect light traps utilizing ultraviole t (UV) light ranging from 340-370 nm were developed after physiological and behavior studies demons trated that house flies

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38 exhibited positive phototaxis toward UV-emitting light sources (Goldsmith and Fernandez 1968, McCann and Arnett 1972). Ligh t traps utilizing glue boards to subdue attracted flies are a common ma nagement tool in indoor settings (Lillie and Goddard 1987). Ultraviolet light traps for indoor use are an a lternative to chemicals, but some factors in urban environments that may limit trap success. As house flies disperse within a building, they may encounter competing so urces of light origin ating from windows or overhead light fixtures which may interfere with trap catch (Pickens and Thimijan 1986). Previous studies demonstrated that increas ing UV output of light traps significantly enhanced catch efficacy of house flies, but they did not take into account light-trap performance relative to compe ting light sources in the urba n environment (Pickens and Thimijan 1986, Snell 1998). Therefore, the first objective of this study was to examine competing light intensities in public settings where light traps would most likely be used, then corroborate those data w ith light-intensity levels in experiments to measure effects of competing light intensity on house-fly re sponse to UV light traps. The second objective was to present house f lies with competing light sour ces with different spectral outputs and quantify their re sponse to UV light traps. Materials and Methods Insects. The Horse-Teaching-Un it (HTU) strain of M. domestica from Gainesville, FL, was used in this research. Larvae from the HTU strain were reared on a medium containing 3 liters wheat bran, 1.5 lite rs water, and 250 ml of Calf Manna (Manna Pro Corp., St. Louis, MO) pellets. All stages of HTU strain were placed on a 12:12 (L: D) photoperiod at 26 1C and 51.03 3.49% RH. Adult flies from both strains were

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39 provided granulated sugar, powdered milk, and water ad libitum and held on a 12:12 photoperiod (L:D) (Hogsette et al 2002). Adult flies were held no longer than 7 days. Before experimentation, adult flies were aspirated from screen cages (25.4 by 53.3 by 26.7 cm) using a handheld vacuum with modi fied crevice tool. Aspirated flies were transferred into a refrigerator (~5C) for 2 min to subdue activity. Flies were removed from the refrigerator and placed on a chilled aluminum tray, counted and sexed. Counted and sexed flies were placed into plastic cups (237 ml), clear plastic lids were placed over the cups, then the flies were held at room temperature for approximately 30 min before being placed into experiments. All flies were handled with camel hair paint brushes and featherweight forceps. Light tunnel design. Enclosed light-tunnel design consists of a release cage attached to a galvanized aluminum light tunne l that terminates in a box enclosing a light trap (Fig. 2-1). The release cage (30 by 30 by 45 cm) was fitted with a sheet-metal bottom and aluminum window screen on the top, sides, and one end. Stockinette was fitted on the remaining end (30 by 30 cm) to allow access into the cage. Release cages were placed on a 10.4 cm-high platform to make them level with a light tunnel entrance. The light tunnel (152 by 20 dia. cm metal duct) was painted with one coat of primer and one coat of flat black paint, then allowed to cure for at least 3 d to eliminate paint fumes. A light-tunnel entrance (20 cm dia.) was cu t into the box enclosure (66 by 91 by 60 cm) that was constructed of corrugated cardboard The 20 cm hole was centered horizontally on the 91-cm face, and was 12.7 cm from ground level. Vents were cut in the top of the box enclosure (17.7 by 38.1 cm) to prevent buildup of heat from light traps. A piece of black organdy was glued over each vent to prevent flies from escaping. A piece of

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40 plywood (91 by 60 cm) was painted with white paint and placed inside the box enclosure opposite the light tunnel entran ce. One UV light trap (Nova, Whitmire Microgen Inc., St. Louis, MO) was mounted with four sc rews onto the white plywood inside the box enclosure. The trap was late rally centered and located dire ctly opposite the light tunnel entrance. The trap utilized three 15-watt UV bulbs (Sylvania Quantum, Manchester, UK) as well as a horizontal (7.6 by 40.6 cm) a nd a vertical glue board (25.4 by 40.6 cm). Ultra-violet (UV) bulbs in traps had < 1000 h use. A wo rkshop fixture containing two 40-watt Sylvania cool-white fluorescent light bulbs was hung 8 cm above release cages to provide a source of background light th at is a common light source in urban environments. The distance of 8 cm above th e cages was selected in order to establish intensity comparable with levels of co mpeting light in urban environments. Procedure. To perform an experiment, new gl ue boards were placed inside traps and all lights were turned on. One hundred se xed flies were released from a plastic cup (237 ml) into a release cage. Experiments commenced when stockinette on the release cages was unfurled and wrapped around the en trance of the light tunnel, allowing flies access to the UV light trap. After 4 h, experime nts were shut down and at the end of each experiment, the release cages were sealed and removed, traps were turned off, and glue boards were collected. The time period of 4 h was selected because preliminary results showed between 90 and 100% of flies within dark controls were caught inside UV light traps after 4 h. Flies not captured were re moved from the experimental set up prior to subsequent repetitions. Ambient temperatur e for all experiments was approximately 27 to 29C. All repetitions contained 100 adult hou se flies (50 M: 50 F) between 2 and 5 d of age.

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41 Light intensity survey of restaurants and grocery stores. A HOBO Light Intensity logger (Onset, Bourne, MA) was used to measur e light intensity inside five restaurants and/or grocery st ores. The logger was held 1.3 m from the ground with its light sensor facing the ceili ng and the researcher carried the logger throughout the establishment in this fashion. Data were co llected at 5-s interval s until a minimum of 100 points were collected at each establishment. Direct sunlight was a voided at all locations because its high intensity may influence averag e measurements of artificial light. Impact of competing light intensity on trap catch. Four intensity levels of competing light were set up based upon the re sults of the field survey. Two workshop light fixtures, each containing two fluorescen t 40-watt light bulbs, were suspended directly above the release cages. A range of 1 to 4 40-watt bulbs were illuminated and provided light intensities ra nging from 27 to 125 lumens/m2. Three replications were conducted per intensity level. Impact of competing light sp ectra on trap catch. Four types of fluorescent light bulbs were presented to house flies as a source of overhead competing light. The bulb models and types were as follows: Sylvania Warm White (F40T12/WW), Sylvania Cool White (F40T12/CW), Sylvania Daylight (F40T12/DX), and Sylvania Blacklight (F40T12/350BL). Two fluorescent workshop light fixtures, each capable of holding two 40-watt light bulbs, were suspended directly above the release cages. Three 40-watt bulbs of each model were placed inside the fixt ures and illuminated during experiments. Four replications were c onducted per treatment. Spectral analyses and relative intensity of all treatments were measured using a USB2000 spectrometer (Ocean Optics, Dunedin, FL). Light intensity for all treatment

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42 outputs was measured with a HOBO Light Intensity logger (Onset, Bourne, MA). Since measurements of light intensity by HOBO Light Intensity l ogger (350 to 700 nm) represented a proportion of total spectrum measured by the USB2000 spectrometer (200 to 820 nm), total light intensity was es timated using the following formulae where Total spectrum units represents relative light in tensity measured by the USB2000 spectrometer and Measured light units represents relative light in tensity perceived by the HOBO Light Intensity logger. Measured light represents the light intensity (lumens/m2) recorded by the HOBO Light Intensity logger and units measured represent intensity counts per nanometer tabulated by USB2000 spectrometer using OOIBase32 software (Ocean Optics, Dunedin, FL). Measured light units Total spectrum units = Proportion Total light output (%) Measured light (lumens/m2) Proportion Total light output (%) = Estimate Total light output (lumens/m2) Once the Estimate Total light output (lumens/m2) was calculated, the intensity levels of UV (350 to 370 nm) and blue-green light (480 to 510 nm) were also calculated. The UV light units and Blue-green light units represent intensity counts per nanometer tabulated by USB2000 spectrometer using OOIBase32 software (Ocean Optics, Dunedin, FL). UV light units Total spectrum units = Proportion UV light output (%) Proportion UV light output (%) Estimate Total light output (lumens/m2) = Estimate UV light output (lumens/m2) Blue-green light units

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43 Total spectrum units = Proportion Blue-green light output (%) Proportion Total light output (%) Estimate Total light output (lumens/m2) = Estimate Blue-green light output (lumens/m2) Statistical analysis. Because all four treatments for the light-intensity experiments and light-quality experiments could not be conducted simultaneously, both experiments were set up using a two-way balanced incomp lete block design. Treatment pairs were randomly assigned a priori for each trial day until all po ssible treatment combinations were met (SAS 2001). A dark control was run concurrently with each experiment. For each dark control, house flies were placed in to a release cage and presented with an illuminated Whitmire Nova trap at the end of the light tunnel without a competing light source placed overhead. Means were separated with a Student Newman-Keuls test. Regression analysis was conducte d on data from light-intens ity experiments to examine the relationship between trap catch and intensity of blue-green light. Another regression analysis was conducted on light -quality experiments to examine the relationship between trap catch and UV intensity. Results and Discussion Light intensity survey. Results of light-intensity survey at area restaurants and grocery stores showed intensity of artific ial and natural light sources ranged from approximately 27 to 91 lumens/m2 (Table 3-1). Light intensity of treatments within laboratory bioassays was within the range of field results (Table 3-2). Impact of competing light intensity on trap catch. The number of males caught in UV traps significantly decreased when inte nsity of the competing light exceeded 91.46 lumens/m2 when compared with dark controls (F= 9.63; df = 4, 50; P < 0.0001) (Table 33). The number of females caught declined significantly when intensity of competing

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44 light exceeded 51.43 lumens/m2 (F= 18.17; df = 4, 50; P < 0.0001) (Table 3-3). When the data were combined, the overall results showed total catch in UV light traps decreased significantly as the in tensity of competing light s ource increased (F = 39.46; df = 4, 50; P < 0.0001) (Table 3-3). As overall competing light intensity was in creased, spectral analyses showed the relative intensity of a blue-green light increas ed 5x from the lowest to highest treatment (Table 3-4; Figs. 3-1 to 34). Regression analysis s howed a significant correlation between increases in blue-green light and decr eases in trap catch (Fig. 3-5). Blue-green light ranging between 480nm and 510nm constituted approxim ately 13% of total light emitted from fluorescent fixtures in all treatments (Table 3-4; Figs. 3-1 to 3-4). Both Pickens and Thimijan (1986) and Shields (1989) have suggested that artificial cool-white fluorescent light adversely aff ected house-fly attraction to UV light traps, but neither study measured spectral output nor measured their eff ects on house-fly behavior. The blue-green light emitted by cool-white fluorescent bulbs in the current study corresponded directly with the bl ue-green sensitivity of the house-fly eye demonstrated in previous studies (Figs. 3-1 to 3-4) (M cCann and Arnett 1972, Bellingham 1995). These results suggest that relatively high intensitie s of competing light containing blue-green wavelengths may distract house flies from rela tively low intensities of ultraviolet emitted from light traps. Approximately 1 to 2% of light emitted from cool-white fluorescent treatments consisted of UV ranging between 350 to 370 nm (Table 3-4; Figs 3-1 to 3-4). Spectral analyses showed the UV emission from fluorescent treatments exceeded the UV originating from light traps by almost 4x when four bulbs were used (Table 3-4; Figs. 3-1

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45 to 3-4). However, the spectrum of the UV cons isted of a narrow spik e that peaked at 365 nm contrasted with the broad-based UV from the light traps ranging from 310 to 399 nm with a peak at 350 nm (Table 3-4; Figs. 3-1 to 3-4). Previous studies have demonstrated that higher intensity of UV out put significantly increased ho use fly catch within light traps (Pickens and Thimijan 1986, Pickens 1989b, Snell 1998). But if house flies in this study were simply responding to UV intensity, then one would expect to find a greater number of flies remaining inside the release cage at the conclusion of the experiments. Bowden and ChurchÂ’s studies (1973) docum ented an inverse relationship between moonlight and trap catch for multiple species of beetles and moths. Since light intensity decreases at a rate equal to the inverse squa re of distance from its source, Bowden and Church (1973) asserted that light traps exer ted a region of influence unique to individual species. Insects outside of this region would remain unaffected by the trap, and modifications to light-trap out put or intensity of competi ng illumination would alter the size of this region (Bowden and Church 1973). If the same concept applies to house flies, then competing fluorescent light originating from multiple overhead light fixtures reduces the region of influence of UV light traps by saturating the environment with fullspectrum fluorescent light. Subsequently, Bowden (1982) estimated that a minimum 12:1 ratio of background light to trap light was necessary to have an adverse effect on light trap performance. This ratio ma y hold for some species of Coleoptera or Lepidoptera, but my lab studies found th at background light intensity must be approximately 25 times greater than light in tensity from a trap to have a significant adverse effect on house fly response (Bowde n 1982). Although this may seem high, intensity of competing light in urban envi ronments can meet or exceed light levels

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46 reported in this study (Table 31). In addition, as the intensity of UV light diminishes over distance, the survey study showed that average light intensity from competing sources remained relatively constant within ea ch restaurant or grocery store (Table 3-1). Impact of competing light spectra on trap catch. Results of the light quality studies showed significantly fewe r male (F = 21.28; df = 4, 64; P < 0.0001) and female house flies (F = 37.85; df = 4, 64; P < 0.0001) were caught among all treatments when compared against a dark control (Table 35). When the data were pooled together, overall trap catch among all treatments was al so significantly lower than the dark control (F = 56.60; df = 4, 64; P < 0.0001), but significantly fewer flies were caught in light traps when competing light consisted of black lig ht versus daylight, cool-white, and warmwhite fluorescent (Tables 3-5 and 3-6; Figs. 3-5 to 3-8). Blacklight bulbs emitted the lowest intensity of blue-green light while day light bulbs emitted the highest intensity of blue-green (Table 3-6; Figs. 3-6 to 3-9). For this study, regression analysis showed a signifi cant correlation between increases in UV and decreases in trap catch (Fig. 3-10). Inte nsity of UV emitted from Blacklight treatments was approximately 10x greater than UV intens ity from daylight, cool white, and warm white treatments (Table 3-6; Figs. 3-6 to 39). In addition, the intensity of UV output from all treatments exceeded UV emitted from li ght traps (Table 3-6; Figs. 3-6 to 3-9). Yet the spectrum of the UV produced by da ylight, cool white, and warm white fluorescent bulbs consisted of a narrow spike peaking at 365 nm contrasted with blacklight treatments and insect light traps which emitted broad-based UV ranging from 310 – 399 nm and peaking at 350 nm (Tab le 3-6; Figs. 3-6 to 3-9).

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47 The M. domestica eye is sensitive to UV light ra nging from 340 nm to 370 nm and blue-green light ranging fr om 480 nm to 510 nm, but ther e is debate over how this sensitivity affects a house flyÂ’s optomotor response (Goldsmith and Fernandez 1968, McCann and Arnett 1972, Thimijan and Pickens 1973, Green 1984). Although bluegreen sensitivity was relatively high, phototactic response by male and female M. domestica gradually declined as light spectra approached 630 nm (Thimijan and Pickens 1973). Results from our light quality expe riments were consistent with previous literature indicating that house flies exhibited a stronger resp onse toward UV versus bluegreen wavelengths (Pickens 1989a). In conclusion, the results of our lab study showed a significant decrease in response of male and female house flies toward UV li ght traps as the intensity of competing fluorescent light was increased. When house flie s were presented four different types of competing light, their response towards UV light traps was significantly lower when competing light sources contained broa d-based UV versus blue-green light.

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48 Table 3-1. Light intensity (lumens/m2) measured within five local restaurants (R) and grocery stores (G) Location n Intensity A (G) 100 27.33 1.59 B (R) 100 28.29 0.37 C (R) 100 50.67 0.80 D (G) 100 61.43 2.42 E (R) 100 91.24 1.28 Table 3-2. Light intensity (lumens/m2) of four intensity trea tments of cool-white fluorescent light measured 45 cm from light source Number of bulbs Total wattage Intensity 1 40 W 27.43 2 80 W 51.21 3 120 W 91.46 4 160 W 125.67

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49 Table 3-3. Effect of intens ity of cool-white fluorescent li ght as a competing light source on number of adult house flies (mean SE) caught in UV light traps (50 M: 50 F per repetition) Light intensity Gender Dark control 27.43 51.43 91.46 125.67 Male 45.25 0.51a 42.66 1.31ab 41.88 1.16ab 40.00 1.49bc 37.00 1.15c Female 47.00 0.58a 45.00 1.28ab 42.66 0.70bc 40.55 1.37cd 38.22 1.35d Total 92.29 0.85a 87.66 1.45b 84.55 1.20b 80.55 0.97c 75.22 0.92d Means within a row with the same letter ar e not significantly differe nt (P=0.05; StudentNewman Keuls [SAS Institute, 2001])

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50Table 3-4. Estimated intensity (lumens/m2) of total spectral output, blue-green output, and ultraviolet output emitted from competing light sources and light traps used in light quantity experiments Number of Estimated total Blue-green output UV output Blue-green Total Cool white bulbs light intensity (480510nm) (350-370nm) + UV output Trap Catch 1 33.01 3.36 0.70 4.06 87.66 1.45 2 59.23 6.46 1.03 7.49 84.55 1.20 3 104.22 11.85 1.26 13.11 80.55 0.97 4 140.60 16.66 1.59 18.65 75.22 0.92 UV Trap 1.95 0.06 0.44 0.50 -

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51Table 3-5. Effect of competi ng light quality on mean number ( SE) of adult house f lies caught in UV light traps (50 M: 50 F per repetition) Competing light source Gender Dark control Warm white Cool white Daylight Blacklight Male 45.91 0.61a 40.25 1.15b 39.16 1.86b 39.66 0.91b 30.83 1.91c Female 46.71 0.63a 35.66 2.14b 33.16 2.61b 34.50 1.21b 21.08 2.13c Total 92.79 0.81a 75.91 2.72b 73.41 1.87b 74.16 1.63b 52.08 3.84c Means within a row with the same letter are not significantly different (P=0.05; Student-Newma n Keuls [SAS Institute, 2001])

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52Table 3-6. Estimated intensity (lumens/m2) of total spectral output, blue-green output, and ultraviolet output emitted from competing light sources and light traps used in light quality experiments Competing light Estimated total Blue-green output UV output Blue-green Total spectrum light intensity (480-510nm) (350-370nm) + UV output Trap Catch Blacklight 73.84 2.02 15.79 17.81 52.08 3.84 Day Light 76.61 11.94 1.27 13.21 74.16 1.63 Cool White 84.80 9.68 1.30 9.98 73.41 1.87 Warm White 89.62 10.57 1.73 12.30 75.91 2.72 UV Trap 1.95 0.06 0.44 0.50 -

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53 Figure 3-1. Spectral analysis and mean intensity (lumens/m2) of 1 Sylvania Cool White fluorescent bulb measured at 61 cm from source. Arrow highlights blue-green peak between 480 and 510 nm. 0 1000 2000 3000 4000 200300400500600700800Intensity (counts) Wavelength (nm) Master Sylvania Cool White 27.43 lumens/m2

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54 Figure 3-2. Spectral analysis and mean intensity (lumens/m2) of 2 Sylvania Cool White fluorescent bulbs measured at 61 cm fr om source. Arrow highlights bluegreen peak between 480 and 510 nm. 0 1000 2000 3000 4000 200300400500600700800Intensity (counts) Wavelength (nm) Master Sylvania Cool White 51.21 lumens/m2

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55 Figure 3-3. Spectral analysis and mean intensity (lumens/m2) of 3 Sylvania Cool White fluorescent bulbs measured at 61 cm fr om source. Arrow highlights bluegreen peak between 480 and 510 nm. 0 1000 2000 3000 4000 200300400500600700800Intensity (counts) Wavelength (nm) Master Sylvania Cool White 91.46 lumens/m2

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56 Figure 3-4. Spectral analysis and mean intensity (lumens/m2) of 4 Sylvania Cool White fluorescent bulbs measured at 61 cm fr om source. Arrow highlights bluegreen peak between 480 and 510 nm. 0 1000 2000 3000 4000 200300400500600700800Intensity (counts) Wavelength (nm) Master Sylvania Cool White 125.67 lumens/m2

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57 y = -0.9108x + 90.723 R2 = 0.9933 74 76 78 80 82 84 86 88 90 024681012141618 Intensity of Blue-green light (480-510nm)Trap catch Figure 3-5. Regression analys is showing relationship between trap catch and intensity (lumens/m2) of blue-green light

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58 Figure 3-6. Spectral analysis and mean intensity (lumens/m2) of Sylvania Blacklight bulbs measured at 61 cm from source. Arrow highlights UV peak between 340 and 370 nm. 0 1000 2000 3000 4000 200300400500600700800Intensity (counts) Wavelength (nm) Master Sylvania Blacklight Bulb 43.46 1.84 lumens/m2

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59 Figure 3-7. Spectral analysis and mean intensity (lumens/m2) of Sylvania Daylight fluorescent bulbs measured at 61 cm fr om source. Arrow highlights bluegreen peak between 480 and 510 nm. 0 1000 2000 3000 4000 200300400500600700800Intensity (counts) Wavelength (nm) Master Sylvania Daylight Bulb 65.9 1.08 lumens/m2

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60 Figure 3-8. Spectral analysis and mean intensity (lumens/m2) of Sylvania Cool White fluorescent light measured at 61 cm from source. Arrow highlights blue-green peak between 480 and 510 nm. 0 1000 2000 3000 4000 200300400500600700800Intensity (counts) Wavelength (nm) Master Sylvania Cool White Bulb 73.81 0.69 lumens/m2

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61 Figure 3-9. Spectral analysis and mean intensity (lumens/m2) of Sylvania Warm White fluorescent light measured at 61 cm from source. Arrow highlights blue-green peak between 480 and 510 nm. 0 1000 2000 3000 4000 200300400500600700800Intensity (counts) Wavelength (nm) Master Sylvania Warm White Bulb 74.04 0.59 lumens/m2

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62 y = -1.5558x + 76.704 R2 = 0.9854 40 45 50 55 60 65 70 75 80 05101520 Intensity of Ultraviolet (350-370nm)Trap Catch Figure 3-10. Regression analysis show ing relationship between tr ap catch and intensity (lumens/m2) of blue-green light

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63 CHAPTER 4 LIGHT TRAP HABITUATION STUDY Introduction The house fly Musca domestica (Diptera: Muscidae) is a nuisance in agricultural and urban environments (Cosse and Ba ker 1996, Moon 2002, Hogsette 2003). High populations of house flies can cause economic losses in livestock, and dispersing house flies are pestiferous in reside ntial and commercial areas (Hogs ette and Farkas 2000). House flies breed in animal waste, dumpsters, and garbage and have been implicated as mechanical vectors of enteric diseases such as Salmonella spp. and Shigella spp. among animals and humans (Imai 1984, Graczyk et al. 2001, Mian et al. 2002). In urban areas, UV light traps are used to ma nage house flies. Insect light traps that utilize ultra-violet light were developed as an alternative to insecticide applications. As house flies enter structures they are exposed to artificial light through time, but it is unknown whether continued exposure to artificial light influen ces their sensitivity to UV light traps. If house flies habituate to bac kground light in their su rrounding environment, then they may be more inclined or disincline d to fly towards a UV-li ght trap. Therefore, the objective of this study was to determin e if previous experience with fluorescent or UV light influences house fly response to UV light traps. Materials and Methods Insects. The Horse-Teaching Unit (H TU) strain of house fly, M. domestica, from Gainesville, FL, was used for all studies presented here. Larvae were reared on a medium containing 3 liters wheat bran, 1. 5 liters water, and 250 ml of Calf Manna

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64 (Manna Pro Corp., St. Louis, MO) pellets. All stages of HTU strain were placed on a 12:12 (L: D) photoperiod at 26C + 1C and ~55% RH. Adult flies from both strains were provided granulated sugar, powdered milk, and water ad libitum and held on a 12:12 photoperiod (L:D) (Hogsette 1992, Hogsette et al. 2002). Adult flies were held no longer than 7 d. Prior to experimentation, adult flies we re aspirated from screen cages using a handheld vacuum with modified crevice tool to aspirate adult flies. Aspirated flies were transferred into a refrigerator (~5C) for 2 min to subdue activ ity. Subdued flies were removed from the refrigerator and placed on a chilled aluminum tray, then counted and sexed. Counted and sexed flies were placed into deli cups (237 ml) and held at room temperature for approximately 30 min. A ll flies were handled with camel hair paintbrushes and featherweight forceps to prevent damage. Light tunnel design. Enclosed light-tunnel design consisted of a release cage attached to a galvanized aluminum light tunne l that terminates in a box enclosing a light trap (Fig. 1). The release cage (30 by 30 by 45 cm) was fitted with a sheet-metal bottom and aluminum window screen on the top, sides, and one end. Stockinette was fitted on the remaining end (30 by 30 cm) to allow access into the cage. Release cages were placed on a 10.4 cm platform to make them le vel with a light tunnel entrance. The light tunnel (152 by 20 dia. cm metal duct) was prim ed and painted with one coat of primer and one coat of flat black paint, then allowe d to cure for at least 3 d to eliminate paint fumes. A light-tunnel entran ce (20 cm dia.) was cut into the box enclosure (66 by 91 by 60 cm) which was constructed of corrugate d cardboard. The 20 cm hole was centered horizontally on 91 cm face, and it was 12.7 cm from ground level. Vents were cut into

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65 the top of the box enclosure (17.7 by 38.1 cm) to prevent buildup of heat from light traps. A piece of black organdy was glued over each ve nt to prevent flies from escaping. A piece of plywood (91 by 60 cm) was painted wit h white paint and placed inside the box enclosure opposite the light tunnel entrance. One UV light trap (Nova, Whitmire Microgen Inc., St. Louis, MO ) was mounted with four sc rews onto the white plywood inside the box enclosure. Th e trap was laterally centered and located directly opposite the light tunnel entrance. The trap utilized three 15-watt UV bulbs (Sylvania Quantum, Manchester, UK) as well as horizonta l (7.6 by 40.6 cm) and vertical (25.4 by 40.6 cm) glue boards. Ultra-violet light bulbs in light traps had less than 1000 h use. A workshop light containing two 40-watt Sylvania cool-white fluores cent light bulbs was hung 8 cm above release cages to provide a s ource of background li ght that is a common light source in urban environments. Procedure. All experiments were conducted in side two buildings (3 by 3 m); each building held two light tunnels. New glue boa rds were placed inside traps and all lights were turned on. One hundred counted and sexe d adult flies were released from a plastic cup (237 ml) into a release cage. Experi ments commenced when stockinette on the release cages was unfurled and wrapped around the entrance of the light tunnel, allowing access to the UV light trap. At the end of each experiment the release cages were sealed and removed, traps were turned off and glue boards were collected. Flies not captured were removed from the experimental set up prior to subsequent repetitions. Ambient temperature for all experiments was 29C. Quality and quantity of light were recorded at the release-cage end of the light tunnel (Fig. 2). Spectral analyses and relativ e light intensities were measured using a

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66 USB2000 Spectrometer (Ocean Optics, Dunedin, FL). Abso lute light quantity for cool-white fluorescent light output and UV-trap output was measured with a HOBO Light Intensity logger (Onset, Bourne, MA). Light habituation treatments. All house flies in primary lab colonies were reared on a 12:12 (L:D) photoperiod using 4 40-watt GE Wide Spectrum Plant and Aquarium bulbs (GE F40PL/AQ) at intensity of 10.28 2.38 lumens/m2. Prior to habituation experiments, house fly pupae were separated from primary lab colonies, placed in a screen holding cage (30 by 17.5 by 30 cm) a nd stored in a separate rearing room. Holding cages were covered on top and thre e sides with aluminum foil to prevent overhead light from entering the cages. The side of the holding cage (30 by 17.5 cm) that was not covered by aluminum foil was placed 12 cm away directly in front of a light fixture. Light fixtures pr ovided either cool-white fluor escent light from four 15W Sylvania Cool White bulbs or UV li ght from four 15W Sylvania Quantum Blacklight bulbs. Cool white fluorescent light was sele cted for this treatment because it is a common source of indoor ligh ting. Emerging adult house fl ies in holding cages were reared on a 12:12 photoperiod (L:D) of either co ol-white fluorescent li ght at intensity of 34.11 0.54 lumens/m2 or black light bulbs at in tensity of 15.88 0.39 lumens/m2 for 2 to 3 d prior to experiments. All hous e flies were provided with powdered milk, granulated sugar, and water ad libitum. Statistical analysis. Since both treatments for th e habituation experiments could not be conducted simultaneously, this st udy was set up using a two-way balanced incomplete block design. Treatme nt pairs were randomly assigned a priori for each trial day until all possible treatmen t combinations were met (SAS 2001). A dark control was

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67 run concurrently with each repe tition. For each dark control, house flies were placed into a release cage and presented w ith an illuminated light trap at the end of the light tunnel without a competing light source placed overh ead. The house flies used in all controls were selected from the original laboratory colonies. A Whitmire Nova light trap was used in all dark controls. Results and Discussion Although all treatments caught significantly fewer house flies than the dark control, there was no significant differe nce in the response to UV light traps among house flies reared on UV light, cool-white light, versus the plant and aquarium light used in the laboratory (F = 11.47; df = 3, 21; P < 0.0001) (Table 4-1). Rearing house flies on blacklight or cool-white fluor escent did not influence thei r response to UV light traps (Table 4-1; Figs. 4-1 to 4-3) If house flies did habituat e to blacklight, then we would have expected a significantly lower response to UV light traps. Conversely, if they habituated to cool-white fluorescent, then we would have expected to see a significant increase in their response to UV light traps. Fukushi (1976) demonstrated that hous e flies could discriminate among narrow ranges of light wavelengths when specific wavele ngths were associated with sugar water. Although this experiment of classical conditi oning was not directly related with my experiment, it does illustrate that visual expe rience with specific wavelengths of light can influence house fly behavior (Fukushi 1976). Pickens et al. (1969) speculated that adu lt house flies exposed to UV-light traps for at least 12 h exhibited a significantly greater response towards light traps compared with adult house flies that did not have previous vi sual experience with UV. This result would suggest that house flies develope d increased sensitivity to UV, not habituation (Pickens et

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68 al. 1969). But our results showed that that pr ior exposure to UV light did not significantly increase or decrease catch efficacy of light traps (Table 4-1). Subsequent studies on visual sensitivity of house flies showed that dark-reared flies re sponded to significantly lower intensity levels of light than house flies rear ed on a 12:12 (L:D) photoperiod (Deimel and Kral 1992). Thus, Deimel and Kral (1992) determined that fly vision developed within the initial 1-5 d after adult emergence and suggested that visual experience within this time frame may influenc e the fliesÂ’ sensitivity to light. However, their research did not compare sensitivity acros s different light spectra, but rather light intensity needed to stimulate the optic nerv e (Deimel and Kral 1992). These results show that the spectrum of light presented to hous e flies during this developmental period did not influence house fly response to overhead or UV light when placed in a bioassay that provides them with a choice of light spectra.

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69 Table 4-1. Mean number of adult house f lies caught in UV light traps after being preconditioned under differe nt light conditions. Pre-conditioning light treatments Gender Control Wide spectrum Black light Cool white Male 45.22 0.51a 40.66 1.31b 36.33 1.16b 36.66 1.49b Female 44.00 0.58a 41.16 1.28b 40.33 0.70b 40.50 1.37b Total 89.22 0.85a 81.82 2.45b 76.66 1.20b 77.16 1.97b Means within a row with the same letter ar e not significantly differe nt (P=0.05; StudentNeuman Keuls [SAS Institute, 2001]).

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70 0 1000 2000 3000 4000 200300400500600700800Intensity (counts) Wavelength (nm) Master Figure 4-1. Spectral analysis and mean intensity of GE Plant & Aquarium fluorescent light used in house fly rearing room. Mean light intensity presented in lumens/m2. Rearing Room GE Plant & Aquarium 10.28 2.38 lumens/m2

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71 0 1000 2000 3000 4000 200300400500600700800Intensity (counts) Wavelength (nm) Master Figure 4-2. Spectral analysis and mean intensity of Sylvania Blacklight used to rear treatment house flies. Mean light intensity presented in lumens/m2. Sylvania Blacklight 15.88 0.39 lumens/m2

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72 0 1000 2000 3000 4000 200300400500600700800Intensity (counts) Wavelength (nm) Master Figure 4-3. Spectral analysis and mean intensity of Sylvania Cool White fluorescent light used to rear treatm ent house flies. Mean light intensity presented in lumens/m2. Sylvania Cool White 34.11 0.54 lumens/m2

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73 CHAPTER 5 SUMMARY AND CONCLUSIONS The main purpose of this research wa s to investigate factors in the urban environment that inhibit the catch efficacy of UV light traps used to manage the house fly, Musca domestica, in urban environments. To do this the first priority was to develop a standard bioassay that eliminated or reduced position effects associated with light-trap placement that influence results. Initial studi es with a light tunnel bioassay demonstrated there were no significant pos ition effects detected among two research buildings, four positions, or box enclosures which enclosed the light traps. In addition, the light-tunnel bioassay minimized air movement and standard ized trap location, trap distance, and background light for future experiments. The first portion of this research investig ated the effect of house fly age on its response to UV light traps. House flies th at were 5 d and younger exhibited significantly greater attraction toward UV light traps than older flies. The second part of the first research chapter used probit analysis to esti mate response time of house flies to UV traps. A catch time for 50% of house flies (CT50) within UV traps was estimated from 99 – 114 min for males and females. The estimated CT50 for total house fly response toward an UV light trap was approximately 1.72 h (103.2 min). The CT90 and CT95 estimates for total house fly catch were 6.01 h (360.6 min) and 8.57 h (514.2 min) respectively. There was no significant difference between male and female response time as evident by overlapping 95% confidence intervals for CT50, CT90, and CT95.

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74 For the second portion of this research, hous e flies were presente d various intensity levels of cool-white fluorescent light in or der to determine whethe r intensity of non-UV competing light sources influenced house fly at traction to UV light traps. Intensity levels in experiments correlated with preliminary surveys of overhead and natural light within local grocery stores and restaurants wher e light traps are commonly used. Results showed that the number of males caught in UV traps significantly decreased when intensity of the competing li ght exceeded 91.43 lumens / m2. Significant declines in catch of females occurred at a lower intensity when the competing light exceeded 51.43 lumens / m2. When the data were combined, the ove rall results showed total catch in UV light traps decreased significantly as the in tensity of competing light source increased. These results demonstrated a significant decrease in respons e of male and female house flies toward UV light traps as the intensity of competing fluorescent light was increased. House flies were also presented with four different types of competing light which covered a broad spectral range from UV to red (700 nm) which is beyond the house flyÂ’s visual perception. Again, house fly response toward UV light traps si gnificantly declined when a source of competing light was intr oduced. However, house fly response towards UV light traps was significantly lower when background light cont ained broad-based UV versus background light containing blue-green light and no UV. Finally, the third portion of this research investigated whethe r or not house flies habituated to light quality within their surrounding environment. House flies from current colonies were compared against house flies reared on black light and cool-white fluorescent light. The results of habituati on experiments showed that all treatments caught significantly fewer house flies than th e dark control. However, there was no

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75 significant difference in the response to UV light traps among house flies reared on UV light, cool-white fluorescent li ght, and grow-lights which are us ed in the rearing rooms. The spectrum of light used in rearing did not significantly influence house fly response to UV light traps. These results also suggest th at previous experience to different kinds of light does not influence house fly response to light traps.

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76 APPENDIX A DIAGRAM OF BUILDING LAYOUT Figure A-1. Diagram of buildings, positions, and bioassay layout at USDA X X a 1 a 2 A 1 2 Building Position Box Enclosure Location of Light Measurements Overhead Fluorescent Li g ht Fixture Release Cage X X b 1 b 2 B 3 4 3m 3m

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77 APPENDIX B SAS PROGRAMS USED FOR DATA ANALYSIS SAS programs for Chapter 2 /Analysis of variance for study standardizing the bioassay/ / ‘Position’ is nested within ‘Building’/ Proc glm data = work.fly; Class building (position); Model male fem total = building (position); Means building (position) / snk; Run; /Analysis of variance for age study/ Proc glm data = work.fly; Class age; Model male fem total = age; Means age / snk; Run; /Probit analyses for Time study/ /Probit analysis for total number of flies caught on glue boards/ Proc probit data = work.fly inversecl log10 lackfit; Class gbtot; Model time/n = hrs /; Run; /N = 500/ /Probit analysis for adult male house flies caught on glue boards/ Proc probit data = work.fly inversecl log10 lackfit; Class male; Model time/n1 = hrs /; Run; /N1 = 250/

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78 /Probit analysis for adult female house flies caught on glue boards/ Proc probit data = work.fly inversecl log10 lackfit; Class female; Model time/n1 = hrs /; Run; /N1 = 250/ /Analysis of variance co mparing light output of four UV light traps/ Proc sort data = work.light; By trap; Proc glm data = work.light; Class trap; Model intensity = trap; Means trap / SNK; Run; /Analysis of variance comparing overhead cool -white fluorescent light measured at four independent positions/ Proc sort data = work.light; By position; Proc glm data = work.light; Class position; Model intensity = position; Means position / SNK; Run;

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79 SAS programs for Chapter 3 Proc sort data = work.fly; by day treatmnt; Proc univariate data = work.fly; Class treatmnt; Var total male fem; Run; / Balanced Incomplete Block Design (BIBD); Two-way analysis of variance (BIBD) of light intensity data / Proc sort data = work.fly; by day treatmnt; Proc glm data = work.fly; Class day treatmnt; Model male fem total = day treatmnt; Means treatmnt / snk; Lsmeans treatmnt / pdiff; Proc glm data = work.fly; Class day treatmnt; Model armale arfem artotal = day treatmnt; Means treatmnt / snk; Lsmeans treatmnt / pdiff; Proc sort data = work.sex; by treatmnt; Proc glm data = work.sex; by treatmnt; Class sex; Model resp aresp = sex; Means sex / snk; Proc sort data = work.sex; by sex; Proc glm data = work.sex; by sex; Class treatmnt; Model resp aresp = treatmnt; Means treatmnt / snk; Run;

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80 /Proc univariate for light quality data/ Proc sort data = work.fly; by day treatmnt; Proc univariate data = work.fly; Class treatmnt; Var total male fem; /Balanced Incomplete Block Design; Two-wa y analysis of variance (BIBD) of light quality data/ Proc sort data = work.fly; by day treatmnt; Proc glm data = work.fly; Class day treatmnt; Model male fem total = day treatmnt; Means treatmnt / snk; Lsmeans treatmnt / pdiff; Proc glm data = work.fly; Class day treatmnt; Model armale arfem artotal = rep treatmnt; Means treatmnt / snk; Lsmeans treatmnt / pdiff; Proc sort data = work.sex; by treatmnt; Proc glm data = work.sex; by treatmnt; Class sex; Model resp aresp = sex; Means sex / snk; Proc sort data = work.sex; by sex; Proc glm data = work.sex; by sex; Class treatmnt; Model resp aresp = treatmnt; Means treatmnt / snk; Run;

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81 SAS Programs for Chapter 4 Proc sort data = work.fly; by day treatmnt; Proc univariate data = work.fly; Class treatmnt; Var total male fem; Run; / Balanced Incomplete Block Design (BIBD); Two-way analysis of variance (BIBD) for light habituation data/ Proc sort data = work.fly; by day treatmnt; Proc glm data = work.fly; Class rep treatmnt; Model male fem total = day treatmnt; Means treatmnt / snk; Lsmeans treatmnt / pdiff; Proc glm data = work.fly; Class day treatmnt; Model armale arfem artotal = day treatmnt; Means treatmnt / snk; Lsmeans treatmnt / pdiff; Proc sort data = work.sex; by treatmnt; Proc glm data = work.sex; by treatmnt; Class sex; Model resp aresp = sex; Means sex / snk; Proc sort data = work.sex; by sex; Proc glm data = work.sex; by sex; Class treatmnt; Model resp aresp = treatmnt; Means treatmnt / snk; Run;

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82 APPENDIX C SPECTROMETRY MEASUREMENTS FO R LIGHT TRAPS AND BACKGROUND LIGHT Figure C-1. Spectral analysis and mean light intensity of Whitmire Nova trap 1 at Position a1 0 1000 2000 3000 4000 200300400500600700800Intensity (counts) Wavelength (nm) Master Position a1 Trap 1 Mean light intensity 1.33 0.15 lumens/m2

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83 Figure C-2. Spectral analysis and mean light intensity of Whitmire Nova trap 2 at Position a2 0 1000 2000 3000 4000 200300400500600700800Intensity (counts) Wavelength (nm) Master Position a2 Trap 2 Mean light intensity 1.34 0.09 lumens/m2

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84 Figure C-3. Spectral analysis and mean light intensity of Whitmire Nova trap 3 at Position b1 0 1000 2000 3000 4000 200300400500600700800Intensity (counts) Wavelength (nm) Master Position b1 Trap 3 Mean light intensity 1.35 0.14 lumens/m2

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85 Figure C-4. Spectral analysis and mean light intensity of Whitmire Nova trap 4 at Position b2 0 1000 2000 3000 4000 200300400500600700800Intensity (counts) Wavelength (nm) Master Position b2 Trap 4 Mean light intensity 1.33 0.17 lumens/m2

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86 Figure C-5. Spectral analysis and mean intens ity of overhead cool-whi te fluorescent light at Position a1 0 1000 2000 3000 4000 200300400500600700800Intensity (counts) Wavelength (nm) Master Position a1 55.92 lumens/m 2

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87 Figure C-6. Spectral analysis and mean inte nsity overhead cool-white fluorescent light at Position a2 0 1000 2000 3000 4000 200300400500600700800Intensity (counts) Wavelength (nm) Master Position a2 53.67 lumens/m 2

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88 Figure C-7. Spectral analysis and mean inte nsity overhead cool-white fluorescent light at Position b1 0 1000 2000 3000 4000 200300400500600700800Intensity (counts) Wavelength (nm) Master Position b1 54.88 lumens/m 2

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89 Figure C-8. Spectral analysis and mean inte nsity overhead cool-white fluorescent light at Position b2 0 1000 2000 3000 4000 200300400500600700800Intensity (counts) Wavelength (nm) Master Position b2 55.01 lumens/m 2

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90 APPENDIX D REARING CONDITIONS FOR CONLONIES OF MUSCA DOMESTICA 20 21 22 23 24 25 26 27 28 29 3008/03/05 09:59:01.0 08/03/05 12:03:31.0 08/03/05 14:08:01.0 08/03/05 16:12:31.0 08/03/05 18:17:01.0 08/03/05 20:21:31.0 08/03/05 22:26:01.0 08/04/05 00:30:31.0 08/04/05 02:35:01.0 08/04/05 04:39:31.0 08/04/05 06:44:01.0 08/04/05 08:48:31.0 08/04/05 10:53:01.0 08/04/05 12:57:31.0 08/04/05 15:02:01.0 08/04/05 17:06:31.0 08/04/05 19:11:01.0 08/04/05 21:15:31.0 08/04/05 23:20:01.0 08/05/05 01:24:31.0 08/05/05 03:29:01.0 08/05/05 05:33:31.0 08/05/05 07:38:01.0 08/05/05 09:42:31.0 Degrees (C) Figure D-1. Temperature (C) of rearing room for adult Musca domestica recorded by HOBO Temp & RH data logger Mean Temperature 26.41 0.19 C

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91 50 52 54 56 58 60 62 64 66 6808/03/05 09:59:01.0 08/03/05 12:02:01.0 08/03/05 14:05:01.0 08/03/05 16:08:01.0 08/03/05 18:11:01.0 08/03/05 20:14:01.0 08/03/05 22:17:01.0 08/04/05 00:20:01.0 08/04/05 02:23:01.0 08/04/05 04:26:01.0 08/04/05 06:29:01.0 08/04/05 08:32:01.0 08/04/05 10:35:01.0 08/04/05 12:38:01.0 08/04/05 14:41:01.0 08/04/05 16:44:01.0 08/04/05 18:47:01.0 08/04/05 20:50:01.0 08/04/05 22:53:01.0 08/05/05 00:56:01.0 08/05/05 02:59:01.0 08/05/05 05:02:01.0 08/05/05 07:05:01.0 08/05/05 09:08:01.0 Relative Humidity (% ) Figure D-2. Relative Humidity (%) of rearing room for adult Musca domestica recorded by HOBO Temp & RH data logger Mean RH 59.94 0.78%

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92 0 2 4 6 8 10 12 14 16 1808/03/05 10:01:18.0 08/03/05 11:56:48.0 08/03/05 13:52:18.0 08/03/05 15:47:48.0 08/03/05 17:43:18.0 08/03/05 19:38:48.0 08/03/05 21:34:18.0 08/03/05 23:29:48.0 08/04/05 01:25:18.0 08/04/05 03:20:48.0 08/04/05 05:16:18.0 08/04/05 07:11:48.0 08/04/05 09:07:18.0 08/04/05 11:02:48.0 08/04/05 12:58:18.0 08/04/05 14:53:48.0 08/04/05 16:49:18.0 08/04/05 18:44:48.0 08/04/05 20:40:18.0 08/04/05 22:35:48.0 08/05/05 00:31:18.0 08/05/05 02:26:48.0 08/05/05 04:22:18.0 08/05/05 06:17:48.0 Lumens Figure D-3. Light intensity (lumens/m2) of rearing room for adult Musca domestica recorded by HOBO Light Inte nsity data logger. Gra ph illustrates 12:12 (L:D) photoperiod Mean Intensity 10.28 2.38 lumens/m2

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93 20 21 22 23 24 25 26 27 28 29 3003/04/05 15:58:34.0 03/04/05 23:06:04.0 03/05/05 06:13:34.0 03/05/05 13:21:04.0 03/05/05 20:28:34.0 03/06/05 03:36:04.0 03/06/05 10:43:34.0 03/06/05 17:51:04.0 03/07/05 00:58:34.0 03/07/05 08:06:04.0 03/07/05 15:13:34.0 03/07/05 22:21:04.0 03/08/05 05:28:34.0 03/08/05 12:36:04.0 03/08/05 19:43:34.0 03/09/05 02:51:04.0 03/09/05 09:58:34.0 03/09/05 17:06:04.0 03/10/05 00:13:34.0 03/10/05 07:21:04.0 03/10/05 14:28:34.0 03/10/05 21:36:04.0 03/11/05 04:43:34.0 03/11/05 11:51:04.0 Temperature (C ) Figure D-4. Temperature (C ) of rearing room for Musca domestica larvae recorded by HOBO Temp & RH data logger Mean Temperature 26.19 0.42 C

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94 0 10 20 30 40 50 60 7003/04/05 15:58:34.0 03/04/05 23:03:34.0 03/05/05 06:08:34.0 03/05/05 13:13:34.0 03/05/05 20:18:34.0 03/06/05 03:23:34.0 03/06/05 10:28:34.0 03/06/05 17:33:34.0 03/07/05 00:38:34.0 03/07/05 07:43:34.0 03/07/05 14:48:34.0 03/07/05 21:53:34.0 03/08/05 04:58:34.0 03/08/05 12:03:34.0 03/08/05 19:08:34.0 03/09/05 02:13:34.0 03/09/05 09:18:34.0 03/09/05 16:23:34.0 03/09/05 23:28:34.0 03/10/05 06:33:34.0 03/10/05 13:38:34.0 03/10/05 20:43:34.0 03/11/05 03:48:34.0 03/11/05 10:53:34.0 Relative Humidity (% ) Figure D-5. Relative Humidity (%) of rearing room for Musca domestica larvae recorded by HOBO Temp & RH data logger Mean RH 51.03 3.49%

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95 0 2 4 6 8 10 1208/03/05 10:03:30.0 08/03/05 12:05:00.0 08/03/05 14:06:30.0 08/03/05 16:08:00.0 08/03/05 18:09:30.0 08/03/05 20:11:00.0 08/03/05 22:12:30.0 08/04/05 00:14:00.0 08/04/05 02:15:30.0 08/04/05 04:17:00.0 08/04/05 06:18:30.0 08/04/05 08:20:00.0 08/04/05 10:21:30.0 08/04/05 12:23:00.0 08/04/05 14:24:30.0 08/04/05 16:26:00.0 08/04/05 18:27:30.0 08/04/05 20:29:00.0 08/04/05 22:30:30.0 08/05/05 00:32:00.0 08/05/05 02:33:30.0 08/05/05 04:35:00.0 08/05/05 06:36:30.0 Lumens Figure D-6. Light intensity (lumens/m2) of rearing room for Musca domestica larvae recorded by HOBO Light Inte nsity data logger. Gra ph illustrates 12:12 (L:D) photoperiod Mean Intensity 6.67 1.44 lumens/m2

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96 LIST OF REFERENCES Agee, H. R., V. M. Kirk, and J. C. Davis. 1983. Comparative spectral sensitivity and some observations on vision related beha vior of northern and western corn rootworm adults (Diabrotica: Coleoptera ). J. Ga. Entomol. Sci. 18: 240-245. Agee, H. R. and R. S. Patterson. 1983. Spectral sensitivity of st able, face, and horn flies and behavioral responses of stable flie s to visual traps (D iptera: Muscidae). Environ. Entomol. 12: 1823-1828. Axtell, R. C. 1970. Integrated fly control program for caged-poultry houses. J. Econ. Entomol. 63: 400-405. Barnard, D. R. and C. J. Geden. 1993. Influence of larval de nsity and temperature in poultry manure on development of the house fly (Diptera: Muscidae). Environ. Entomol. 22: 971-977. Barnard, D. R., R. H. Harms, and D. R. Sloan. 1998. Biodegradation of poultry manure by house fly (Diptera: Muscid ae). Environ. Entomol. 27: 600-605. Bellingham, J. 1995. A comparative study of the spectral sensitivity, antennal sensilla, and landing preferences of the house fly, Musca domestica (L.) (Diptera: Muscidae), and the lesser house fly, Fannia canicularis (L.) (Diptera: Fanniidae), Dissertation, Biology. Queens University, Belfast. pp. 130. Bidawid, S. P., J. F. B. Edeson, J. Ibrahim, and R. M. Matossian. 1978. The role of non-biting flies in the transmi ssion of enteric pathogens (Salmonella species and Shigella species) in Beirut, Lebanon. Ann. Trop. Med. Parasitol. 72: 117-121. Borror, D. J., C. A. Triplehorn, and N. F. Johnson. 1989. An introduction to the study of insects. Harcourt Brace College Pubishers, Fort Worth, TX. Bowden, J. 1973. The influence of moonlight on catch es of insects in light traps in Africa. Part I. The moon and moon light. Bull. Ent. Res. 63: 113-128. Bowden, J. 1982. An analysis of factors affecting catch es of insects in light traps. Bull. Ent. Res. 72: 535-556. Bowden, J. and B. M. Church. 1973. The influence of moonlight on catches of insects in light traps in Africa. Part II. The ef fect of moon phase on light trap catches. Bull. Ent. Res. 63: 129-142.

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97 Bryant, E. H. 1970. The effect of egg density on ha tchability in two strains of the housefly. Physiol. Zool. 43: 288-295. Buchan, P. B. and R. S. Sohal. 1981. Effect of temparature a nd different sex ratios on physical activity and life sp an in the adult housefly, Musca domestica. Exp. Geront. 16: 223-228. Buchan, P. B. and R. B. Moreton. 1981. Flying and walking of small insects (Musca domestica) recorded differentially with a sta nding-wave radar act ograph. Physiol. Entomol. 6: 149-155. Burg, J. G. and R. C. Axtell. 1984. Monitoring house fly, Musca domestica (Diptera: Muscidae), populations in cage-layer poul try houses using a baited jug-trap. Environ. Entomol. 13: 1083-1090. Carlson, D. A. and M. Beroza. 1973. Field evaluations of (Z)-9-tricosene, a sex attractant pheromone of the house fly. Environ. Entomol. 2: 555-559. Carlson, D. A., R. E. Doolittle, M. B eroza, W. M. Ragoff, and G. H. Gretz. 1974. Muscalure and related compounds. I. Res ponse of houseflies in olfactometer and pseudofly tests. J. Agr. Food Chem. 22: 194-196. Chapman, J. W., P. E. Howse, J. J. Knapp, and D. Goulson. 1998. Evaluation of three (Z)-9-tricosene formulations for control of Musca domestica (Diptera: Muscidae) in caged-layer poultry units. J. Econ. Entomol. 91: 915-922. Chapman, J. W., J. J. Knapp, and D. Goulson. 1999. Visual responses of Musca domestica to pheromone impregnated targets in poultry units. Med. Vet. Entomol. 13: 132-138. Cosse, A. A. and T. C. Baker. 1996. House flies and pig manure volatiles: Wind tunnel behavioral studies and elect rophysiological evaluations. J. Agric. Entomol. 13: 301-317. Deimel, E. and K. Kral. 1992. Long term sensitivity adjustment of the compound eyes of the housefly, Musca domestica, during early adult life. J. Insect Physiol. 38: 425-430. Driggers, D. P. 1971. Field evaluation of blacklight elec trocutor grids for the control of flies associated with poultry, Master s Thesis, Entomology and Nematology. University of Florida, Gainesville, pp. 33. Elvin, M. K. and E. S. Krafsur. 1984. Relationship between temperature and rate of ovarian development in the house fly, Musca domestica L. (Diptera: Muscidae). Ann. Entomol. Soc. Amer. 77: 50-55.

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98 Fatchurochim, S., C. J. Geden, and R. C. Axtell. 1989. Filth fly (Diptera) oviposition and larval devlopment in poultry manure of various moisture levels. J. Entomol. Sci. 24: 224-231. Fletcher, M. G., R. C. Axte ll, and R. E. Stinner. 1990. Longevity and fecundity of Musca domestica (Diptera: Muscidae) as a func tion of temperature. J. Med. Entomol. 27: 922-926. Fukushi, T. 1976. Classical conditioning to vi sual stumuli in the housefly, Musca domestica. J. Ins. Physiol. 22: 361-364. Geden, C. J., J. A. Hogsette, and R. D. Jacobs. 1999. Effect of airflow on house fly (Diptera: Muscidae) distribution in p oultry houses. J. Econ. Entomol. 92: 416420. Goldsmith, T. H. and H. R. Fernandez. 1968. The sensitivity of housefly photoreceptors in the mid-ultraviolet and the limits of the visible spectrum. J. Exp. Biol. 49: 669-677. Graczyk, T. K., R. K. Knight, R. H. Gilman, and M. R. Cranfield. 2001. The role of non-biting flies in the epidemiology of hu man infectious diseases. Microbes and Infection 3: 231-235. Green, C. H. 1984. A comparison of phototactic responses to red and green light in Glossina morsitans and Musca domestica. Physiol. Entomol. 16: 165-172. Greenberg, B. 1973. Flies and disease, Volume 2. Biology and disease transmission. Princeton University Press, Princeton, NJ. Gruebel, P., J. S. Hoffman, F. K. Chong, N. A. Burstein, C. Mepani, and D. R. Cave. 1997. Vector potential of houseflies (Musca domestica) for Helicobactero pylori. J. Clin. Microbiol. 35: 1300-1303. Haupt, A. and J. R. Busvine. 1968. The effect of overcrowding on the size of houseflies (Musca domestica L.). Trans. R. Ent. Soc. Lond. 120: 297-311. Hecht, O. 1970. Light and color reactions of Musca domestica under different conditions. Bull. Ent. Res. 16: 94-98. Hogsette, J. A. 1992. New diets for production of house f lies and stable f lies (Diptera: Muscidae) in the laboratory. J. Econ. Entomol. 85: 2291-2294. Hogsette, J. A. 1995. The house fly: Basic biol ogy and ecology, pp. 71-76. In H. H. Van. Horn [ed.], Nuisance concerns in anim al manure management: Odors and flies. Florida Cooperative Extension, University of Florida, Gainesville, FL.

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105 BIOGRAPHICAL SKETCH Matthew D. Aubuchon, son of David and Claire Aubuchon, was born February 7, 1974, in St. Louis, Missouri. He graduated from St. Louis University High School in 1992. After high school, he attended Indiana University and graduated with honors in 1996 after completing the requirements for the degree of Bachelor of Science with a major in environmental science and public po licy. During his seni or year of college, Matt moved to Washington, D.C., for an inte rnship at the nonprofit organization Center for Policy Alternatives. During the summ ers of 1995 through 1997, Matt acquired his aquatic-applicator license and worked on over 100 lakes throughout Indiana and Michigan abating invasive speci es of aquatic plants. Matt moved to Auburn in Fall of 1997 and worked as a laboratory technician for the Auburn University Department of Entomology. In winter, 1998, he was accepted into the graduate entomology program at Auburn University, where he pursued his master Â’s degree under the guidance of Dr. Gary Mullen. After finishing his M.S. in August, 2001, Matt promp tly moved to Gainesville, FL, to pursue his Ph.D. at the Entomology and Nematology Department under the guidance of Dr. Phil Koehler. On April 23, 2005, Matt was married to Amanda Kathleen Chambliss in St. Augustine, FL.