• TABLE OF CONTENTS
HIDE
 Title Page
 Acknowledgement
 Table of Contents
 List of Tables
 List of Illustrations
 Introduction
 Literature review
 Sterilization with tepa and...
 Dispersion
 Population densities
 Discussion
 Summary and conclusions
 Literature cited
 Biographical sketch
 Copyright














Title: Chemosterilization, dispersion and population densities of the eye gnat Hippelates pusio Loew
CITATION PDF VIEWER THUMBNAILS PAGE IMAGE ZOOMABLE
Full Citation
STANDARD VIEW MARC VIEW
Permanent Link: http://ufdc.ufl.edu/UF00091313/00001
 Material Information
Title: Chemosterilization, dispersion and population densities of the eye gnat Hippelates pusio Loew
Series Title: Chemosterilization, dispersion and population densities of the eye gnat Hippelates pusio Loew
Physical Description: Book
Creator: Williams, David F.,
 Record Information
Bibliographic ID: UF00091313
Volume ID: VID00001
Source Institution: University of Florida
Holding Location: University of Florida
Rights Management: All rights reserved by the source institution and holding location.
Resource Identifier: alephbibnum - 000431401
oclc - 37907912

Downloads

This item has the following downloads:

Binder1 ( PDF )


Table of Contents
    Title Page
        Page i
    Acknowledgement
        Page ii
    Table of Contents
        Page iii
    List of Tables
        Page iv
    List of Illustrations
        Page v
        Page vi
    Introduction
        Page 1
        Page 2
        Page 3
    Literature review
        Page 4
        Page 5
        Page 6
        Page 7
    Sterilization with tepa and metepa
        Page 8
        Page 9
        Page 10
        Page 11
        Page 12
        Page 13
        Page 14
        Page 15
        Page 16
        Page 17
        Page 18
        Page 19
        Page 20
        Page 21
        Page 22
        Page 23
        Page 24
        Page 25
        Page 26
        Page 27
        Page 28
    Dispersion
        Page 29
        Page 30
        Page 31
        Page 32
        Page 33
        Page 34
        Page 35
        Page 36
        Page 37
        Page 38
        Page 39
        Page 40
        Page 41
        Page 42
        Page 43
        Page 44
        Page 45
        Page 46
        Page 47
        Page 48
        Page 49
        Page 50
        Page 51
        Page 52
        Page 53
        Page 54
        Page 55
        Page 56
        Page 57
        Page 58
        Page 59
        Page 60
        Page 61
        Page 62
    Population densities
        Page 63
        Page 64
        Page 65
        Page 66
    Discussion
        Page 67
        Page 68
        Page 69
        Page 70
        Page 71
        Page 72
        Page 73
    Summary and conclusions
        Page 74
        Page 75
        Page 76
    Literature cited
        Page 77
        Page 78
        Page 79
    Biographical sketch
        Page 80
        Page 81
    Copyright
        Copyright
Full Text









CHEMOSTERILIZATION, DISPERSION AND POPULATION

DENSITIES OF THE EYE GNAT

HIPPELATES PUSIO LOEW













By
DAVID F. WILLIAMS












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






UNIVERSITY OF FLORIDA
1969















ACENOWLEDGENTS


I wish to express my appreciation to the numerous individuals who

assisted throughout this study.

My deepest appreciation goes to Dr. Louis C. Kuitert, chairman of

the supervisory committee, for his encouragement and guidance.

I am especially gratefulto Dr. G. C. LaBrecque of the Laboratory

of Insects Affecting Man and Animals, Entomology Research Division, Agri-

culture Research Service, USDA, for his invaluable suggestions and assist-

ance.

I wish to thank Dr. W. G. Eden, Chairman of the Department of

Entomology, Dr. F. S. Blanton, and Dr. L. Berner who served as members

of the supervisory committee.

The largest indebtedness and affectionate appreciation go to my

wife, Sylvia, for her encouragement, patience, and understanding during

this period of graduate study.


















TABLE OF CONTENTS


Pace


ACKNOWLED ENTS . . . . . . . . . . .

LIST OF TABLES . . . . . . . . . . .

LIST OF ILLUSTRATIONS . . . . . . . . .

INTRODUCTION . . . . . . . . . . .

LITERATURE REVIEW . . . . . . . . . .
Chemosterilization of Insects . . . . .
Dispersion and Population Densities of Eye Gnats .

Part I. CHEMOSTERILIZATION TESTS . . . .


STERILIZATION WITH TEPA AND METEPA . . . . .
Studies on Autosterilization . . . . .
Chemosterilant Treated Screen . . . .
Over an Attractant . . . . .
On Inner Surface of Holding Container.
Treated Foam Strands Placed on Pupae .
Treated Foam Strands Placed on Anesthetized


Adults.


Studies on Elapsed Time Required to Migrate Through Foam .
Multiple Mating Test . . . . . . . . . .

Part II. DISPERSION AND POPULATION DENSITY STUDIES .


DISPERSION . . . . . .
Laboratory Studies . . . .
Field Studies . . . .

POPULATION DENSITIES. . . . .
Reproductive Capacities .. .

DISCUSSION. . . . . . . .
Chemosterilization of Eye Gnats.
Dispersal Tests . . . .
Population Density Studies .


SUMMARY AND CONCLUSIONS . . . . . . .

LITERATURE CITED . . . . . . . .

BIOGRAPHICAL SKETCH . . . . . . . .


. . . . 0


. . . . . . .
. . . . . . .
. . . . . . .


. . . . . . I
. . . . . . .

. . . . . . .
. .


. 7LI















LIST OF TABLES


Table Page

1. Per cent sterility and mortality in male eye gnats after
being placed in a holding jar containing a baited cup
covered with screen treated with 5.0 per cent metepa. . . 13

2. The per cent sterility and mortality in 2-to 3-day old
colonized male and female eye gnats following exposure to
5.0 per cent or 10.0 per cent metepa residues on nylon
mesh screen . . . . . . . . .. .. . . 1. 5

3. Per cent sterility and mortality in 2-to 3-day old colo-
nized adult and field-collected adult eye gnats follow-
ing exposure to 5.0 per cent or 10.0 per cent metepa resi-
dues on nylon mesh screen ... . . . . . . . 16

h. Per cent sterility and mortality in eye gnats following
migration as newly closed adults through 10-centimeter
layer of polystyrene foam strands treated with 5.0 per
cent tepa or metepa . . . . . . . . . 19

5. Per cent sterility and mortality in eye gnats following
migration as newly closed adults through 15-centimeter
layer of foam strands treated with 5.0 per cent tepa or
metepa. . . . . . . . . ... ....... 20

6. Per cent sterility and mortality in eye gnats following
recovery from carbon dioxide and migration through 15-cen-
timeter layer of foam strands treated with 5.0 per cent
tepa or metepa . . . . . . . . . . . 21

7. Elapsed time required for newly closed adult eye gnats
to escape from the puparia and migrate upward through a
15-centimeter layer of foam strands. . . . . . 23

8. Elapsed time required for anesthetized adult eye gnats to
recover and migrate upward through 1&-centimeter layer of
foam strands . . . . ..... . . . .. 2.

9. Per cent egg hatch from crosses between untreated female
(UF), treated male (TM), and untreated male (Tl) eye
gnats . . . . . . . . . . . . . 27

10. Population density of the eye gnat 1i. pusio calculated
from collections of marked and unmarked _tants at the
horticulture farm. The area surveyed was 527 acres . .. .71















LIST OF ILLUSTRATIONS


Figure Page

1. Modified glass funnel-plastic cylinder trap used to collect
eye gnats. . . . . . . . . . . . 10

2. Map of horticulture farm. Trapping sites designated O,
release site designated X . . . . . . . . . 30

3. Dispersal pattern of marked field-collected H. pusio 24
hours following release . . . . . . . . 35

4. Dispersal pattern of marked field-collected H. pusio 48
hours following release . . . . . . . . . 37

5. Dispersal pattern of marked field-collected H. pusio 72
hours following release . . . . . . . 39


6. Dispersal pattern of marked field-collected H. pusio 96
hours following release . . . . . .

7. Dispersal pattern of marked laboratory-reared (F139)
H. pusio 24 hours following release . . . . .

8. Dispersal pattern of marked laboratory-reared (F139)
H. pusio 48 hours following release . . . . .

9. Dispersal pattern of marked laboratory-reared (F139)
H. pusio 72 hours following release . . . .. .

10. Dispersal pattern of marked sterilized field-collected
H. pusio 24 hours following release . . . . .

11. Dispersal pattern of marked sterilized field-collected
H. pusio L8 hours following release . . . . .

12. Dispersal pattern of marked sterilized field-collected
H. pusio 72 hours following release . . . . .

13. Dispersal pattern of marked sterilized field-collected
H. pusio 96 hours following release . . ..

14. Dispersal pattern of marked laboratory-reared (F1lO)
H. pusio 21 hours following release . . . ...

15. Dispersal pattern of marked laboratory-reared (FlI0)
H. pusio 48 hours following release . . . . .


. . 41


. . 43


. . 45


.. . 7


. 50


. 52


. . 54


. . 56


. . 61









Figure Page

16. Population densities of the eye gnat H. pusio collected
in baited traps at the horticulture farm and honey plant
areas during a 2 year period ................. 65














INTRODUCTION


The eye gnat, a small fly of medical and veterinary importance, be-

longs to the genus Hippelates of the family Chloropidae (Diptera). This

fly is abundant and is a pest in many areas of the world. In the United

States, the most important species are Hippelates pusio Loew in the south-

east and Hippelates collusor (Townsend) in the southwest. Because they

are attracted to sores, cuts, secretions, and natural orifices of man and

animals, eye gnats can act as mechanical carriers of diseases. In the

past, they have been incriminated in the mechanical transmission of yaws

(Kumm and Turner, 1936), conjunctivitis (Herms, 1926), mal de pinto

(Blanco and Soberon, 19hh) in man, and bovine mastitis in cattle (Sanders,

19h0). More recently this incrimination has been extended to nephritis

(Bassett, 1967) in man and possibly anaplasmosis in cattle (Roberts, 1968).

The vexatious nature of the eye gnat can also cause a loss of man-

hours in agricultural fields, reduce efficiency of military personnel,

become a nuisance around outdoor recreational areas, and annoy resting

and feeding animals. The latter can result in weight loss, low milk

yield, and other disorders to the animal.

There are no known effective control measures against the eye gnat.

Present recommendations favor the use of larvicides or adulticides. How-

ever, because of the large areas to be treated the former is expensive and

the latter is effective for such a short period of time that relief is

negligible.


- 1 -







-2-


One of the more promising methods of insect population control began

with the sterilization of screwworm flies Cochliomyia hominivorax (Coquerel)

by gamma radiation and the successful release of these flies into a natural

population. The eventual eradication from Florida and the southeastern

United States of this destructive pest of livestock initiated an enormous

amount of interest and research in the sterility method for insect control.

Unfortunately, the use of radiation in sterilizing insects has certain

disadvantages; it is expensive, stationary, and unable to induce sterility

in a natural population.

Knipling (1959) proposed the theoretical advantages of the use of

chemicals to induce sterility in a large segment of the natural popula-

tion. LaBrecque et al. (1960) pointed out that various compounds in-

duced sterility in house flies, Musca domestic Linnaeus. He later showed

that sterility of a similar type caused by radiation could be induced in

male and female house flies by aziridinyl derivatives (apholate, aphamide,

and tepa), compounds he named chemosterilants (LaBrecque, 1961).

If chemosterilants are to be used in an insect control program it is

absolutely necessary that such factors as population size determinations,

reproductive capacity indexes, compatability of laboratory reared insects

with natural populations and techniques for rearing and sterilizing large

numbers of insects for release be resolved.

As little of this information is available, the major purposes of this

study were: (1) to investigate the feasability of chemically sterilizing

eye gnats using an autosterilization technique, (2) to determine the dif-

ferences if any, between dispersion of laboratory reared and field gnnts,

and (3) to determine population densities of field eye gnats. Many other

tests were performed in relation to the major objectives, of Len rc:ultini






-3-


in new problems rather than resolving the ones under study.

The use of chemosterilants to control the eye gnat offers much

promise; however, many questions need to be resolved before a feasible

control program could be initiated.
















LITERATURE REVIEW


Chemosterilization of Insects

Prior to 1958 very little work was done in chemosterilization of

insects; however, the cytotoxic and mutagenic effects of chemicals on

Drosophila were reported by Auerbach and Robson (19h7). Bird (1950) re-

ported that some alkylating chemicals produced sterilant effects in

Drosophila. The practical usefulness of these chemicals was not noticed

until the eradication program on the screwworm fly proved successful.

Chemosterilants are chemicals that cause sexual sterility in insects

by (1) preventing the development of sperm or ova, (2) causing the death

of the sperm or ova after they have been produced, or (3) injuring the

genetic material of the sperm and ova,producing multiple dominant lethal

mutations. The third mode of action is preferred because males steril-

ized in this fashion usually compete readily with normal males for avail-

able females, and the transfer of motile sperm to these females satisfies

the mating requirements to the same extent as in mating with normal males

(Smith et al., 1964).

Several classes of chemicals are known to contain compounds that arc

insect chemosterilants. Turner (1968) lists five classes plus some mis-

cellaneous compounds not representative of these classes.

The largest and most successful class of chemosterilants are the

alkylating agents. These compounds replace hydrogen with one, two, or

more alkyl groups and have the ability of combining with electron-rich


- It -










centers (electrophilic). The antifertility effects caused by these agents

are believed to be the result of alkylation of some target nucleophile(s),

compounds the alkylating agents react with, thereby preventing its utiliza-

tion in the process of insect reproduction. The specific molecules) in-

volved is not known (Turner, 1968). A complete and thorough review of

insect chemosterilization is presented by LaBrecque and Smith (1968).

The most important and most numerous groups cf biological alkylating

agents are the derivatives of aziridine (Borkovec, 1966). Three of these

compounds (tepa, apholate, and metepa) have been used by previous workers

in sterilizing Hippelates species.

Schwartz (1964) reported that both sexes of H. pusio were capable of

being sterilized in the adult stage by feeding on sugar solution treated

with tepa, metepa, and apholate. The female usually required a slightly

higher concentration for sterility than the males.

Mulla (1968) studied the effects of tepa, metepa, apholate and 16

other compounds on H. collusor in California. He sterilized this species

using a feeding, contact, and pupal dipping method of application.

Apholate proved highly effective against laboratory reared H. collusor.

Dispersion and Population Densities of Eye Gnats

Numerous papers and textbooks have been written on dispersion and

population density studies of insects. Some of the more recent, com-

prehensive works are Andrewartha (1961) who discussed various aspects of

dispersion and Southwood (1966) reporting on ecological methods used in

studying insect populations. Clark et al. (1967) outlined the develop-

ment of ecological principals in theory and practice.

In 1941 Bigham, reporting on the eye gnat in the southeastern United

States, compiled the first detailed survey of gnat breeding areas by


-5-







-6-


using baited traps and recovery cages. His results indicated that H. pusio

was the predominant species and pest in this area and that in Florida this

species breeds in soil which has been freshly disturbed by plowing, har-

rowing, digging or other means. Thus, the eye gnats are abundant in areas

where a large proportion of the land is under cultivation.

Dow and Hutson (1958) described a new bait trap used in measuring

adult populations of H. pusio in Georgia. The seasonal peaks of this

species occurred from July through September.

Dow (1959) tagged field adult eye gnats with radioactive phosphorus,

p32, and when releasing them I and 1 mile from a rural community found

that the eye gnats almost completely penetrated the small town on the day

of release.

Mulla and March (1959) reported on flight range dispersal patterns

and population densities of H. collusor in California. Gnats tagged with

radioactive phosphorus dispersed into agricultural and residential areas

where favorable breeding conditions existed and avoided virgin desert

regions. Dispersal occurred both upwind and downwind with the greatest

distance traveled, 4.3 miles, with the wind. The population density was

estimated at 3,000 to 5,000 gnats per acre. Gnats were found resting at

night on dry or damp ground, on soil clods, on dried rootlets protruding

above the ground, and on foliage of low-growing plants.

































PART I


CHEMOSTERILIZATION TESTS















STERILIZATION WITH TEPA AND METEPA


Studies on Autosterilization

The laboratory strain of H. pusio was established by Turner in 1958

from eye gnats collected around Orlando, Florida and has been reared con-

tinuously.

The field strain of eye gnats was collected at the University of

Florida's horticulture farm with a modified version of the glass funnel-

plastic cylinder trap (Fig. 1) designed by Ruff (1967). The modification

consisted of shortening the funnel stem to 2 millimeters in length, thus

facilitating the movement of eye gnats into the plastic collection cylinder.

A mixture of 20 medium sized shrimp and 500 milliliters of distilled water

was placed in a 2-quart jar covered with a screened lid and held outdoors

for 36 hours. This putrefying mixture was used as the attractant.

All adult eye gnats were anesthetized with carbon dioxide, separated

according to sex and maintained in separate containers until needed. The

holding containers consisted of 3 types: pint standard mason jars used

to hold 15 gnats or more, 10-dram glass shell vials used to hold 10 gnats

or less and 2-quart standard mason jars used for a few special tests.

The gnats were restrained in the containers by covering the open end

with nylon mesh (32 x 32) screen. Sections of cotton dental rolls satu-

rated in honey-water were made available to all gnats before and after

most tests.

The chemosterilants used were tepa (tris (l-aziridinyl) phosphinc

oxide) and metepa (tris (2-methyl-l-aziridinyl) phosphine oxide) which


- 8 -






























Figure 1.--Modified glass funnel-plastic cylinder trap used to collect
eye gnats.















iO
I
o
iI



-'J .m

f
CU






- 11 -


were obtained from the USDA Insects Affecting Man and Animals Laboratory

in Gainesville. The chemosterilants were kept at 0h C and when needed

were diluted with absolute methanol or absolute ethanol.

Three autosterilization methods were used to sterilize the eye gnats.

These were: (1) adults were exposed to chemosterilant residue on nylon

mesh (32 x 32) screen which had been immersed in a 5.0 per cent or 10.0

per cent metepa-methanol solution for 10 minutes and allowed to air dry

for 16 to 2h hours, (2) newly closed adults were allowed to migrate

through chemosterilant treated polystyrene foam strands (2.0 to 8.0 cm.

long and 0.2 to 0.5 cm. in diameter), and (3) anesthetized adults were

allowed to recover and crawl through treated polystyrene foam strands.

Untreated polystyrene foam strands and nylon mesh screen soaked in abso-

lute methanol or absolute ethanol were used as controls in all tests.

The use of treated polystyrene foam strands in sterilizing insects was

first described by Fye et al. (1968) in an autosterilization technique

developed for the house fly Musca domestic L.

After exposure to the chemosterilant, treated eye gnats were caged

with an equal number of untreated laboratory virgins of the opposite sex

and of approximately the same age.

Four to five days later sterility was evaluated in the following

manner. A random sample of 100 eggs, or the total if less than 100,

that had been laid on the wall of each jar was collected and placed on

larval medium. The containers with the larval medium were placed in

emergence cages and newly emerging adults were counted. The per cent

progeny failing to reach the adult stage,after accounting for natural

mortality, determined the degree of sterility obtained. Sterility and

mortality were corrected for control mortality and sterility by Abbott's






- 12 -


(1925) correction formula.

Chemosterilant Treated Screen

Over an Attractant.--This method consisted of 7 replications using 10

laboratory males 2 to 3 days of age per replicate. The adults were placed

in 2-quart jars along with a plastic jelly cup (bottom diameter 2.7 cm.,

top diameter h.3 cm., and height h.0 cm.) containing the shrimp attractant.

The top of the jelly cup was covered with a circular piece of nylon mesh

screen previously treated with metepa. The eye gnats were confined with

the attractant and the treated screen in the jars for 2h hours. Eye gnats

were noticed to be crawling and resting on the treated screen when visual

observations were made at prescribed intervals during the exposure period.

After the exposure period, the gnats were removed from the 2-quart jars,

placed in clean pint jars, and held 4 to 5 days for determining mortality.

Following the holding period, 5 virgin laboratory females were placed in

each jar. Prior to exposure to the treatment the males were not fed, how-

ever, following exposure, honey-water was made available when they were

transferred to the clean holding containers. Sterility was evaluated as

previously described on Page 11 and the results of the tests are shown in

Table 1.

Since the males were only confined in the same container and did not

have to come into contact with the treated screen, the per cent sterility

obtained was quite high ranging from 78 per cent to 92 per cent with a

mean of 81 per cent and mortality never exceeded 27 per cent.

On Inner Surface of Holding Container.--In this method the first test con-

sisted of 15 eye gnats exposed to 5.0 per cent and 10.0 per cent metepa-

treated nylon mesh screen. The test was replicated h times with each sex.

The metepa treated screen was placed in pint jars in such a manner






- 13 -


Table l.--Per cent sterility and mortality in male eye gnats after being
placed in a holding jar containing a baited cup covered with
screen treated with 5.0 per cent metepa.


Replication Number eggs Sterility* Mortality*


1 59 88 19

2 57 8t 18

*3 65 86 22

4 83 92 27

5 52 88 21

6 100 78 15

7 76 90 23


by Abbott's correction


*Corrected for control mortality and sterility
formula. 10 males per replicate.










that the entire inside area of the jar was covered. Thus, the eye gnats

were nearly always in contact with the treated screen during the exposure

periods of 10 and 30 minutes. After exposure, the gnats were transferred

to clean pint jars and held for h to 5 days during which mortality was

recorded. The treated gnats were then crossed with untreated virgins of

the opposite sex and sterility was evaluated following the previously

described technique. The results are given in Table 2.

Sterility was greater in the males than in the females which is in

agreement with the findings by Mulla (1968) on H. collusor. Mortality

was approximately the same for both sexes.

In the second test, 15 adults of mixed sexes were exposed to nylon

mesh screen treated with either 5.0 per cent or 10.0 per cent metepa. The

gnats were exposed for 10-and 30-minute periods and held for h to 5 days

to determine the effects of the concentration of the sterilant and the

exposure period on survival. After this period the gnats were crossed

with virgins of the opposite sex and sterility determined following the

procedure described previously. These tests were performed with gnats

reared in the laboratory as well as those collected in the field. Each

test was eplicated twice for exposure period, eye gnat strain, and metepa

concentration. The results are given in Table 3.

The highest sterility and mortality was obtained with field-collected

adults. Laboratory-reared adults were more difficult to sterilize and

showed a slightly lower mortality in all tests except one.

Generally as the exposure period was increased, both the sterility

and mortality increased. This was also true for the concentration of 1nctcpa.






- 15 -


Table 2.--The per cent sterility and mortality in 2-to 3-day old colonized
male and female eye gnats following exposure to 5.0 per cent or
10.0 per cent metepa residues on nylon mesh screen.




Sex Replicatione-; Metepa Exposure time Sterilityy- Mortali ty-,-
() (min.)
1 10 65 4

5
2 30 72 9

Male
3 10 78 14

10
4 30 81 18


5 10 63 5

5
6 30 69 7
Female
7 10 74 16
10
8 30 78 17


4Corrected for
formula.


control mortality and sterility by Abbott's correction


s*l15 gnats per replicate.






- 16 -


Table 3.--Per cent sterility and mortality in 2-to 3-day old colonized
adult and field-collected adult eye gnats following exposure to
5.0 per cent or 10.0 per cent metepa residues on nylon mesh
screen.



Hippelates Metepa Exposure time Sterility- Mortality*
Strain (%) (min.)

10 82 7
5
30 85 9
Field
Adults 10 86 13

10
30 89 16

10 78 4
5
30 78 8
2 to 3 day old
colonized
(F136) 10 83 10
Adults
10
30 84 16



iCorrected for control mortality and sterility by Abbott's formula.

15 gnats per replicate.






- 17 -


Treated Foam Strands Placed on Pupae

In the second method of autosterilization 2 tests were carried out

using treated polystyrene foam strands covering pupae. Laboratory (Fl and

F135 generation) pupae 3 to 5 days old were separated from the larval

medium by sifting the medium through a series of 10 mesh and 16 mesh

screens. The 10 mesh screen removed the larger material while the pupae

were retained by the 16 mesh screen. Since pupae are difficult to obtain

in large numbers from natural breeding niches, field-collected eye gnats

of mixed sexes were placed in 2-quart mason jars and held for egg produc-

tion. Eggs were collected and the larvae reared to Fl generation pupae.

Six replications with 100 pupae per replicate were used in the two tests.

In each test a different thickness of the layer of the expanded poly-

styrene foam strands was used to cover the pupae. The thicknesses used

were 10 centimeters and 15 centimeters.

Prior to each test the foam strands were treated with 5.0 per cent

tepa and metepa by immersing in the chemosterilant-ethanol solution for

10 minutes and allowing them to air dry for 16 hours. One-hundred pupae

were placed in a 1 gallon ice cream carton and covered with the treated

foam strands to the selected depth.

When the adults emerged they migrated upward and crawled through the

treated foam strands. They were collected, isolated according to sex,

crossed with untreated laboratory virgins of the opposite sex, and sterility

evaluated according to the previously described technique.

The results of the first test using 10 centimeters of treated foam

(Table h) indicated that Fl adults were easier to sterilize than F135

adults with both tepa and metepa, however, the mortality was very high.

Tepa yielded the highest sterility when Fl pupae were used and mctcpa the






- 18 -


least mortality when using F135 pupae. In this test all adults were

sterilized using the 10 centimeter layer of foam strands.

In the second test (Table 5),where foam layers of 15 centimeters in-

stead of 10 centimeters were used, the results show that 99 to 100 per

cent sterility was obtained with Fl adults. However, the mortality was

so high, it cancelled the advantages of the high sterility obtained. Al-

though sterility was lower in the F135 adults, mortality was also much

lower, especially in the tests where metepa was used.

Treated Foam Strands Placed on Anesthetized Adults

In the third method of autosterilization, treatment was very similar

to the second method; however, anesthetized adults rather than pupae were

covered with 15 centimeter. layers of 5.0 per cent tepa or metepa-treated

polystyrene foam strands.

Field-collected and laboratory-reared adults were anesthetized with

carbon dioxide, separated according to sex, placed in containers and gently

covered with foam. One hundred adults were used in each test and each test

replicated four times with each chemosterilant. As the adults recovered

from the anesthesia and crawled upward through the foam, they were collected,

sexed, and crossed with untreated laboratory virgins of the opposite sex

and sterility assessed as previously described. These results are given

in Table 6 and are by far the best obtained in all chemosterilant tests.

Sterility was high while mortality was very low. The highest sterility

was obtained using tepa on field-collected adults. The least mortality

occurred when using 2-to 3-day old laboratory adults.

Studies on Elapsed Time Required to Migrate Through Foam

Tests were conducted to determine the mean time required for eye

gnats to crawl through a 15-centimeter layer of foam.






- 19 -


Table h.--Per cent sterility and mortality in eye gnats following migra-
tion as newly closed adults through 10-centimeter layer of
polystyrene foam strands treated with 5.0 per cent tepa or
metepa.


Hippelates Chemosterilant Sterility* Mortality-
Strain used


97 69

Fl Tepa 99 67

96 63

96 59
Adults Metepa
97 67

96 59

77 46

77 43
F135 Tepa
80 32

85 13

Adults Metepa 84 12

90 11


*Corrected for control
formula.


mortality and sterility by Abbott's correction


100 pupae per replicate.






- 20 -


Table 5.--Per cent sterility and mortality in eye gnats following migra-
tion as newly closed adults through 15-centimeter layer of
foam strands treated with 5.0 per cent tepa or metepa.


Hippelates Chemosterilant Sterility* Mortality*
Strain used


100 80

Fl Tepa 100 82

100 79

100 70


Adults Metepa 99 70

100 71

89 59


F135 Tepa 84 49
87 53

94 13


Adults Metepa 98
97 17


iCorrected for control
formula.


mortality and sterility by Abbott's correction


100 pupae per replicate.






- 21 -


Table 6.--Per cent sterility and mortality in eye gnats following recovery
from carbon dioxide and migration through 15-centimeter layer of
foam strands treated with 5.0 per cent tepa or mctepa.


Hippelates Chemosterilant Sterility*- Mortalityi'-
Strain used


100 7

Field- 100 h
collected Tepa
Adults 99 5

100 h


9h 2

85 4
Metepa
92 1

90 1


95 0

90 1
2 to 3 day old Tepa
colonized 91 2
(F135)
Adults 90 0


92 0

87 1
Metepa
90 1

84 1


correction


100 adults per replicate.


iCorrected for control mortality and sterility by Abbott's
formula.






- 22 -


In the first test newly closed adults from two laboratory strains

were used. Ten pupae were placed in a clear plastic cylinder 22.5

centimeters long and 5.0 centimeters in diameter and covered with a 15

centimeter layer of tepa-treated polystyrene foam strands. A piece of

black plastic was wrapped around the cylinder,causing emerging adults

to travel upward through the foam as quickly as possible. A flap was

cut in the black plastic so emerging adults could be timed immediately

upon eclosion. These tests were performed in a darkened room with only a

small microscope light shining at the top of each plastic cylinder during

observation and timing. A stop-watch was started as soon as the emerging

adult began leaving the puparium and stopped when the adult was no longer

in contact with the polystyrene foam strands. Each test was replicated

5 times with each strain. The results of these tests are given in Table

7.
/
The mean exposure time was 15 minutes 2h seconds, with a range of

12 minutes 2 seconds to 18 minutes 50 seconds. There was very little

difference between the Fl and F135 adults mean elapsed time from eclosion

to emergence from the foam.

Scherer (1963), reporting on H. pusio, found the average duration of

emergence from the puparia for females was 2 minutes 3 seconds and for

males it was 5 minutes 36 seconds. The time elapsed between emergence

and flight was about 32 minutes.

In this next series of tests, the same procedure as described in the

previous test was followed, except that in this instance 2-to 3-day old

adults of the laboratory strain and adults of indeterminate age from the

field-collected gnats were used instead of pupae.

The adults were anesthetized with carbon dioxide, placed in the






- 23 -


Table 7.--Elapsed time required for newly closed adult eye gnats to
escape from the puparia and migrate upward through a 15-
centimeter layer of foam strands.


Hippelates Replication* Elapsed Time
Strain Min. Sec.


Fl 1 12 2

Adults 2 13 45

3 16 56

4 16 25

5 16 5


6 18 50
F135
7 15 4
Adults
8 15 3

9 13 3l

10 17 16


*10 gnats per replicate






- 2h -


plastic cylinders and covered with a 15-centimeter layer of tepa-treated

foam strands. The stop-watch was started as soon as the foam strands

were placed on top of the eye gnats and stopped when the gnats were no

longer in contact with the foam. The results of these tests are shown in

Table 8.

The mean exposure time was h minutes 26 seconds. These adults

migrated through the foam strands approximately 11 minutes faster than the

newly closed adults.

Because the second and third methods of autosterilization basically

did not differ except for age of adult used, the high mortality that

occurred in the second method was unexpected. However, when the means of

the elapsed times were compared the reason for high mortality becomes

evident. The anesthetized adults recovered and migrated upward through

the foam almost four times as fast as did the newly closed adults. The

longer time needed by the newly closed adults to migrate through the

treated foam resulted in a longer exposure time which probably is indica-

tive of the high mortality.

Multiple Mating Test

In these studies tests were conducted to determine whether females

mated more than once. Untreated virgin laboratory females were crossed

with sterile males and egg hatch recorded. These same females were then

crossed with untreated laboratory males and hatch again determined. These

tests were also repeated with the sterile male--fertile male sequence

reversed.

The males used in this test were sterilized by exposure to 5.0 per

cent metepa-ethanol treated polystyrene foam strands. The test was

replicated twice and the male : female ratio used in each replication was






- 25 -


Table 8.--Elapsed time required for anesthetized adult eye gnats to
recover and migrate upward through 15-centimeter layer of
foam strands.


Hippelates Replication- Elapsed time
Strain Min. Sec.


1 6 20

2 3 43

Field- 3 4 22
collected
Adults 4 8 10

5 3 32


6 1 25

7 7 10
2-to 3-day old
colonized 8 5 33
(F135)
Adults 9 1 20

10 2 4o


--10 gnats per replicate






26 -


5:3. The results of this test are given in Table 9.

The sperm in the first mating was retained by the female and the

second mating probably diluted the first. Sterility would then depend on

the ratio of treated sperm to untreated sperm. These results conform

with those obtained by Flint (1964) using cobalt 60 gamma rays on H. pusio.






- 27 -


Table 9.--Per cent egg hatch from crosses between untreated female (UF),
treated male (TM), and untreated male (UM) eye gnats.


Replication Crosses Egg Hatch ({)
(in order of occurrence)


TM x UF 0
1
UM x UF 31


TM x UF 0
2
UM x iUF 33


U x UF 53
3
TM x UF 15


UM x UF 66

TM x UF 8



































PART II



DISPERSION AND POPULATION DENSITY STUDIES















DISPERSION


Laboratory Studies

The adult eye gnats used in all dispersal studies were market with

"Day-Glo" daylight fluorescent pigment manufactured by Switzer Brothers

Incorporated. The four colors used were saturn yellow, rocket red, hori-

zon blue and arc yellow.

Preliminary tests revealed that 0.05 grams was the optimum amount of

fluorescent dust needed for treating containers used for marking. The

gnats were marked by placing the fluorescent dust in a 2 quart standard

mouth mason jar, and rotating the jar until the dust was evenly dispersed

on the inside. Approximately 1000 anesthetized adults were placed in the

jar which was slowly rotated, the marked gnats were removed, placed in a

holding cage (61 cm. x 47 cm. x 51 cm.) and allowed to recover. Honey-

water was made available to all gnats before and after marking. The marked

gnats were held for 6 hours for mortality recordings. Finally, the hold-

ing cage containing the marked eye gnats was transported to the release

site at the University of Florida's horticulture farm (Fig. 2). This farm

is located 10 miles NW of Gainesville and consists of 527 acres of which

260 are under cultivation with the remaining portion in woodland and pine.

The 37 trapping sites were randomly selected over the entire 527 acres.

All releases were made from June to September on a Monday at approx-

imately 3:00 PM. Wind direction, wind velocity and air temperature were

recorded at the release area. The relative humidity was taken from re-


- 29 -








- 30 -


Wa. iyfCl Vq~Ls4
tL .A All~


HORTICULTURAL UNIT


Ir. Z, -Z;-,. 1; FLORIDA AGRICULTURAL EXPERIMENT STATION
"i* A .....^ "' GAINESVILLE, FLORIDA
;V= l =I A,,

Cf- r -
-Z. '-. 1 -Z

k*, ; .. .. .,. .'-, ". --. ,- : .-- :..- -, .:- ,C.-, : I

... .:..
....... .. .. -..........
:::::% ...
;;:: ::..jiiiii ii i :".



S.' .. iI::::::::::::::: ::::::l ,
.. ... Q i, -. -. . . ,. . ... -
'It '... ..... .. .. ... .........,.. I.. ... .,. ,, .,:, ,.



I 5 ( :: .::. .::::.::::::: ::::::. ,. .......






... ... .............. ........... ..: ....-....-......".".te...
F i g u r e . . . .. ..o r .i c u. t. r : : : a: r : T r a p p i' n g ,. i t e- -::. ..0'.." ". .': : '"


s e t
":::::1 : :' ": .. I1 j. i ,^ e. i i "; :








/ V 0 __:__: 660:::: ::::::: 1 66 ft. 1320 feet
.... :::: : ::l:: :::::':::::: ";. -; -" ":"'' "utiva...













r. ... : : ...n.. . p ree stand


.site designated X .. .. : ..... ..-
= = === == ===:= == = =. = 'iiii li.L iiiii i i iii ,.. iii '-'.% ::::::: ..' 1.' ,,- '- -,. "










"F"'"v "l- 'r J=.' ;r' pietrestn
Figure~I 2.-a ofhriutr ar. Tapn ie ds9ae" 'O :'ecI







- 31 -


cordings of the general (10 square mile) area.

A mixture of putrefying shrimp and distilled water was used as the

attractant for baiting the traps and this was replenished every third day.

The traps were set with the attractant before the release was made. Plas-

tic collection cylinders on each trap were changed daily for a 2-week

period following each release. The collections were returned to the lab-

oratory and checked for marked individuals by using a shortwave ultraviolet

(UV) light. After the marked gnats were removed and counted from each

collection, the remaining gnats were then placed on a piece of filter paper

and crushed with the head of a nail dipped in acetone. The filter paper

was then checked under the UV light. Any marked gnats that might have

escaped the first detection were easily spotted using this method described

by Steiner(1965).

The length of time that the fluorescent dust would persist on a marked

individual and the longevity of marked eye gnats versus unmarked gnats were

preliminary problems that needed answering. Thus, field-collected adults

and laboratory-reared adults were marked and placed in outdoor holding

cages (61 cm. x 47 cm. x $1 cm.). Food was made available, tests were

checked daily until the mortality reached 100 per cent and the experiment

was terminated. Each test involved 400 eye gnats and was replicated twice.

The length of time the fluorescent dust would persist was checked by

daily removing all dead marked eye gnats from the cages and placing them

under the UV light. All marked gnats were easily detected throughout the

test when placed under the UV light.

When using field-collected adults, marked individuals lived an average

of 16 days while the unmarked control adults averaged 19 days. However,

when using laboratory eye gnats, marked individuals lived an average of 45






- 32 -


days while unmarked control gnats averaged h3 days. In the latter tests

the marked individuals lived longer than the control individuals. This

would indicate that the marking technique used had little effect on the

longevity of the eye gnats.

Field Studies
Four independent releases each consisting of approximately 12,000

marked adult eye gnats were made using the following H. pusio strains:

(1) field-collected eye gnats, (2) laboratory-reared (F139) gnats, (3)

sterilized field-collected eye gnats and (h) laboratory-reared (FlhO)

gnats.

In a 5th release, approximately 36,000 marked adults were used in the

following proportions: (1) 12,000 sterilized field-collected gnats, (2)

12,000 laboratory-reared (Fll) eye gnats and, (3) 12,000 laboratory-

reared (Fl) gnats.

Because 95 per cent of all field-collected adults were females, this

ratio was also used whenever laboratory adults were released. Thus, all

dispersion tests relate mainly to the female of H. pusio.

In the first release approximately 12,000 field-collected eye gnats

marked with a rocket red fluorescent dust were released at the horticulture

farm. Wind velocity was h miles per hour, with the wind direction from the

IW. The air temperature at ground level was 30.60 C. The average relative

humidity during the week of the release was h3.2 per cent.

Released gnats appeared to linger for a few minutes at the release

site and then fly off in all directions. The outcome of this dispersal

test is given for 2h-, h8; 72; and 96-hour trapping results.

The marked gnats readily dispersed upwind and downwind over the area.

The farthest distance of dispersal (Fig. 3) was approximately 3630 feet






- 33 -


(1100 meters). Of the 37 traps that were set, 22 of them collected marked

gnats during the 24 hours following the release. The number of traps col-

lecting marked gnats 48 hours after the release declined to 10, however,

the dispersion was still good (Fig. 4).

The results of 72 and 96 hours indicate the marked gnats were still

being collected ; however, the number of traps yielding marked individuals

had declined to 7 and 6, respectively. These results are shown in Fig. 5

and Fig. 6.

Marked eye gnats were not collected in any traps after 96 hours even

though traps were operated for 7 days after this period.

In the second release, approximately 12,000 laboratory-reared (F139)

gnats were marked with a horizon blue fluorescent dust and released at the

horticulture farm. The release was made 30 minutes after a rainstorm and

the wind velocity and direction was 3 miles per hour from the NE. The air

temperature at ground level was 27.80 C and the weekly average relative

humidity was 45.0 per cent. It became rather difficult to get the marked

gnats to leave the holding cage; however, as soon as this was accomplished,

the released eye gnats began landing on the personnel at the release site.

Neither of these incidents occurred in the first release when field eye

gnats were used.

The results of this dispersal test are given for 21, 48, and 72 hours.

The marked eye gnats were no longer collected after 72 hours following the

release.

The farthest distance of dispersal was approximately 1200 feet (360

meters). During the period 24 hours following the release only 3 traps

collected marked eye gnats (Fig. 7). The number of traps collecting marked

gnats increased to 7 for the 48 hour results (Fig. 8), however, this number

decreased to h during the 72 hour period (Fig. 9). Dispersion shown by



























Figure 3.--Dispersal pattern of marked field-collected H. pusio 24 hours
following release.



C= traps that collected marked and unmarked gnats

= traps that collected only unmarked gnats












-w Release site
"--" "- O" 0 Traps collecting marked gnats

.....:: ':. - .:i -"T"::: i = Traps collecting unmarked gnats
:: ........ .. .
......... : : i l..........
J i; : : : :............. ......... : :

Si::: :: ::: ::. ::::



-- -p-- -U-- , . ......
.. .... ............... .........





'. .... : :::.::::::: .

.-N ":',;J: ::: ::i:::::. t?^^% %
*^ .*i;.: r .-:': m n: : Ir ;::::::::;;:::ii -r ';;^'^ '.l'';^ '?''^ ^^^;I'l:{- ,-*1


... ,...... ..
.. ....... ........... Z'C"l"
";]3~i~I ~ i i ii i ":::::::~ liiiiii'i~i : F :::::- .... :::I -::::::;-::'i "...... I..



S: :: ::::::::::::
S: ................ .............
: .liii.i i ,.!i ~I~ .............
... :-L ;; 3 i .. .... :: i~ii .. ,,i ... .. :::: ::: :I i. .. ... . .. .. ... L : .. .



,. -L, ._,. '::::: . .::::::: ,.- .
,.. ...... ... ' ,
IJ ~:~:~~~~j:~,-:~~~:~ r:: .~































Figure 4.--Dispersal pattern of marked field-collected H. pusio 48 hours
following release.










=== I -f x1..I L..3 it


- Release site
QtCLE"' I' "t" C14II = Traps collecting marked gnats

..- ... ........ 77, 7- Traps collecting unmarked gnats

.. ".." L .........* ):'. 7-:- -I f5c 1
.. ......... ....

.i.... /iii l ii ) ii i .... i ii ,i

.... . . .










^-i'!i:;:i^ !i JJ" | i||liii ^ lliylii 3!-ii;-II .;!;?:^.^ ^
.. .......... .. ...................... I



l"Z+N i? i` : : iiiil :: ::: :::.:` ` ;; ;k.. : :: '':::i :: :: '..: . ` ;
I ;' . ,. .... .., ii ...t. .. . 1... .. .-. :,.;.,; ,., ,I f





I' i ...^....'............II' .....l, ............... .. : ..........- ...... ,";' '.
-1 .-12 V-, LIZ] .. ......... :X :-.h ........... .:.
S... .. ... .. ::::..: I.... ... II.::::::::. ... ... ..... 1::::::::: *.... I:
. . . - ,' i+ .....: ............. ..... ..... .. ,
..... .. ............ ............................ .... ......
.. .. ......_i .: i- . . I: Ii : .. ....... .. . ..


-q . . . . ........... .. .. . . .. . i

-. .......... ,,. .~: .i.~ ....... i _~ ... ii:........... ., ,,( ... .: .,. . . ..


































Figure 5.--Dispersal pattern of marked field-collected H. pusio 72 hours
following release.












S' %~" I .7 j Release site
- Traps collecting ednt
:: ..-i0-= Traps collecting marked gnats

%A-
........ Traps collecting unmarked gnats

.... ........... ....:::::::::::::: ...::::::::: :: N

... ) i, -. "- "..' ..:::::.........:...... -

.. .iii..i ii.. .. iii .i ......':I




'^<*::::::: ::: ::::::::::::: : ; Iiii_ .;,:j_ ^ ^.. ... ..
......... ...






.,::t:.-.:: : |:: ::- : : 1 <')::: 11::jl"::::" :::" :::::::::::::::::::*::::: "n-^ ^ ^ .'. ; :,-:: ......; .- ^
......... .
... ...... ......
: : .-- :;..,, ...... ... ... .. j .... -. 4... . . .:: .:: ::... . *



.......:: ......... ... I., ,
...... ..::: :: ..........

SI : :: ::::: == == = == = == = l: :::T ::T:i -.F'2 -
: r: ... .. ..... ... ..... i:: .........
....... .::.............. ...........
S" : ...... ". ...... .......................... ............ I
S.::::::: ............. ..........;
.-'.-- L:: ::: :::: ::::: ::::: : : : :--\\ j ; ; ;::"-/--+ .

,. . . . . .
., ,. . . .. ::.: :.. ...:-:.: :: : : . .

..- .'". ...i. _. :, .: .: ::: :: .:::::... .. .
J .7..i : :::: :::::::::::: ::.::::::::.::... ": : : ,. ':: : "
. .-..........

































Figure 6.--Dispersal pattern of marked field-collected H. pusio 96 hours
following release.












.. :. Release site

~ Traps collecting mIarke gnats

D ,-' = Traps collecting unmarked gnats
^<^^ 5^ ^ :::::::::::::: :: ::::::::::::
..... i,,
.;......... :::::1 1. ...........



m S^ i :i -Ii !iiiiiiiiii'i! !iilii.ii'inif i" ;;,
..... .....
..............:.. ...I ......... .


................. ..... ......
.-','..-::i;.:: :: Ir:: :Tl'" :'"g "-"' ='; J ::::::::::. illlJ; :

S.... i li:11 L............... lr:: ::I; :ii : ![


i' ..... ."j 1 -',. iT::::::.:-- -- ." ..... .: ;:: :. -
-\ .b'- rJ . 'C( -. .. : : : : : : : .. .J I..,:(;.. 1:..., .........
-.. ...........
S . ... . . .. C . . . . .. . . . . . . . . . . .
:.:::::: -- . '' . :::::..:: ..........
...... I .. . ::::. ... ..
: ,, :. ,::::.......: ::: :: ; 2 : ... .......... tt: ,



.... ........ ..............


iI==7 : ___ ____
(' ", : : :; :c .. -: :'J I -'": ...... : : 2 : ::: : .........: :::::I ::: .. . -, ;': :' : ,



S........ .. ;-'. ,. .' .',-
: ": "f ' :. . . . . . . I ' " . ....
d+ z Cs:


































Figure 7.--Dispersal pattern of marked laboratory reared (F139) H. pusio
2h hours following release.











S 1 Release site

., Traps collecting marked gnats

t:: ..........: = Traps collecting unmarked gnats


9 ij iij. Ii __ iikS p ..
............. .:::: :::::::
., ....:.. .:::::i :: :::: ..:::::::: I .r. !






... r............... . .. .. . . . .
!lti: ; iii: :iii: :i ii : : I :::::::::::::: l^. .-... i




...............i ............................
. . . . . .. : : .




"3 -- "' ::::::::::....:::::: :. . . ..
@' : ::::::::::i ; -'11;:-F *:i^ ;^.^ ^ .






: ......... .. .. 3..... ...... ....,. ......... .
::' '. :T.. ........... .. .. . '
i ..-*.i.... ...:::::!1
:::: :. .::.::::::: : :: :: .... ... ....-.. ,' -'
....... ...... _., ....... ,. ... .... ..... ... ........... 1,3.: LI.. ....
~::: : ' ......- ""l::::::I '" " ".."" .'....
: :: :I .: .... ,' ... ... ... ........ I





~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~~ ~;; %'- '., i; t ...... 1, I .... '11 ........ I...... .. .......-: ', "I {
,.,::: l~iiil .q .. . . .. .. .. 4. --
k ...-, ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ :T '.;*" I[ .l,: ...... : ....... ,... ,- ,,,..- .-- iT-. :=.- ...,,-w .c .




. . ..~~~. l l.. .. I I] .. .. .. . . .'. . i t... . .
i I iI .'I l l. .I . . . U l + i I I I I I I I


































Figure 8.--Dispersal pattern of marked laboratory reared (F139) H. pusio
48 hours following release.











S= Release site
." Traps collecting marked gnats

::::::. : : : |: Q- Traps collecting unmarked gnats

l,^ i :^:::::::::::::: :1:ii ::;
''^ H^ ^ ^ S ^ ^i;,l : :::::::::::::I: :::: : : f::":, /^. ^c ^;iV?^
..............
: : ::" ............ I: i i Sj
.... ....- !-Z,-q '-i
.. ... ..



S. . .. .......lI.-.. .. ..._1

iL jL...:11W7:]::::::2j ;!^ ^
:::::: .....: :: ::: :::.. ............:.- .
.; *--...- --..^: i:,- -:: ::i- .....::::::: : .,,'-"-.::! :::^::::: ::: : : ^^^



.....L ... .... "..... .....,.. .-
-. ...... II :' ::: ::: -:::i': -:: : ::.. ..-I::
.... .... j ....... V e /:
t_ ..... ... ... -- ,: .. tvr .-.--. ..- . ...... ..
^jj'::l : | : ^ j; | : 11111; I li^ ^: ::::::::::::: ::::" ;






S .......... -
.. .. . . -- . .. ... ... .. .. . .. .. ...._. . . .. .
.. .. ....~t i .~ '~ ...... a ,l...... . I' ; c.............. I i I I ............ .
:-::::::: .. ........
............ .......... ...... .. :.- ,,.< .
...... i...... ............ : .......... .. .. : : :::::: .... :",l
- "" I .... " .......... .. ....i . f ... .i ,, i :;J... .. ........


::-..' .;:: : %-i.:..! :: ;: :-: :. i - ,:y : ,:a-. :.,_ -- .: .:. :.. .?i


































Figure 9.--Dispersal pattern of marked laboratory reared (F139) H. pusio
72 hours following release.















'K= Release site

0= Traps collecting marked gnats


i?...,.-.i~lf~j~~Traps collecting unmarked gnats
.........~.....


..........



.1,.


it~~~rjt?;kt~E5L~Lr~sJL-) r 1L i

I-A
A1 CA Rm-Cy
1 IL ; o








= w.... . .. ..- :C I, -,'

IF..
............. ...............
'.7,: 1 F rn .. .........






... ... .
*.............
............ .,, ..~LLViC:
I~r ~ ii. T-- -:-F-ii
17 :77 _7'; 7 : t~s
..........."-
.. .. .. . .. .
... .............. ............ ell:c


~f~t~ ~..............
~ ~~ .e .. .z::r~:7r:-m
.. ............
... ........ % ~ ~ C~E
t~f~ jP5LL









these eye gnats was definitely inferior to that displayed by the field gnats

used in the first release.

The third release consisted of approximately 12,000 tepa-sterilized

field-collected adults marked with saturn yellow fluorescent dust. The eye

gnats were anesthetized with carbon dioxide, placed in containers and

covered with 15 centimeters of polystyrene foam strands treated with 5 per

cent tepa in ethanol. As the gnats recovered and crawled upward through

the foam, they were assumed to be sterilized. Sterility obtained was 98

per cent in a random sample of 100 individuals. This release was made

about 20 minutes following light rain showers. The air temperature at

ground level was 36.70 C and the average relative humidity for the week

of the release was h3.0 per cent. The wind velocity was 3 miles per hour

from the NW. The released gnats did not linger but flew off in all direc-

tions. Some individuals appeared to fly about 3 meters and then land on

the ground.

The results for this release are given in 2h-, 8-, 72-and 96-hour

periods. Marked gnats readily dispersed over the cultivated area of the

farm. The 2h hour results (Fig. 10) indicated the farthest distance of

dispersal by these gnats as 2300 feet (700 meters). Both the 2h hour and

h8 hour results (Fig. 11) show 12 traps that collected marked adults. This

number of traps declined to h and 6 for the 72 hour and 96 hour results,

respectively (Fig. 12 and Fig. 13).

Ten days after this release was made a trap collected one marked eye

gnat. The dispersion pattern displayed by these sterilized field-collected

adults was quite similar to that shown by the untreated field adults in the

first release. This would indicate that sterilizing the eye gnats had

little effect on their dispersion.
/


- 48 -


































Figure 10.--Dispersal pattern of marked sterilized field-collected H.
pusio 24 hours following release.










.,-.,, Release site


^r-r'iI^ (.-)- Traps collecting unmcarked gnats

77,*,':;*- -^ <^& _ L-7 .... I l,;Traps-..-lectig;-.-.rk;:,g.at
..............


*., ......... ..... . : .: z. '- '


::::.....: .......... : :I:


1, ::::: ::::.:.:......: : : : : . . .. , .
o..... . I
.j : : 1LJ . . : 2 : .-.*................. .


F:: .: ::::::: :::: ::: :::: : ; .. 1,,. ;.-.mr.- 1 ;..,.... ...: ,i .'
. .... .. .. . C o e

i L. i I II Ii
:: ; .. .. .: : : :: :.,, .IL', ... .. .. ", fs' ..........:: :: ** ** :: i: :1 :" : : "'". "':. !,.-" .'::::: ,'; '; '. i -- A ^ p :
.. . .. . ........ . -..-.... .. ... . .- i
;.. I{ , 1 ~~... ............ ,.. ',
m r 'e ', m -l . m. . . . ..l. . . .. I ' '


A.y ,. .. . I ,, . ............... A I --zO


41I
: e'."'i :: :'I; :! : T". I -_2.if;. ,.:. "''::]r.-. 7_ F. T . <: q : :''r '

i--.' i ii i! l ii it :: :i ; : :; :'".''I': f:: :: :: :,:_::_;__i l:,''.,' i ". .'.,,. I

































Figure ll.--Dispersal pattern of marked sterilized field-collected H.
pusio 48 hours following release.













.o Release site

STraps collecting marked gnats

7 :77---"- "'::-- Traps collecting unmarked gnats
:::::::::::::::::::::::::::::


.. ......... .... ..............



.... ......_ ..... .... .A.-.'
".... .....


::::.. .: . .. : : .I 1 .... : :::: I ::.
.......... .. ...



:::::: :.... :: :: : : :. ; :: :::: :
.. ..... .: .. . C...... .........




~.. .s.* ,' .....~..... . ........... ................... .......... .. '.... ;:
- "Jill : : . I .. .. . .. .. . .. . . ... '. ', .. .. ,'"q '" ,, ', .,} 'P '









}* : '*"*-* : .:-' ''- % : ,% .'1. .. .... ... ........... ........ ;.z- -', l -=..-,



































Figure 12.--Dispersal pattern of marked sterilized field-collected H.
pusio 72 hours following release.










SRelease site
,. -,';, *....'- "* 0 =Traps collecting marked gnats
.....; ... : Traps collecting marked gnats
; .-. ....-.......
........... ... ..|-........:: ,

!^ ^ -::::: :11A:::, ^ . :^ !... ....

V. 4:. :::T:. : 7: :::: :: ::: ::: :::: :: 4.. .... *: ;. .
"t-t i :: :l: : : . .-.....
..... i ..... ... :.. ....... .



S^ ^ i^-^i,'. : i:: !^;;;;;;! ^
......::::.:..i:..... .,. ." ."..:i :""
L.-" :l.- .- "J L ........ "' ":" "iil: ^^'; ;"""' ^
...... : : ,; -,~ ,'::::::: .._.. .. .. ....... *...: F . ,^.,


"1 4I. 1 4-: 7cII
L: : i .J .... .: -. .. ., . ". ....-

1 J . . . :.::.. . . .
, *: .-'< -,,'$ : :: ? i: : :J 1: : ; ; : : ; 11_i :--: i: !.;_ ;_. i.: i: i^ i*^ ^ *^- .^ i .'.-'*-,- -: ; .
', ii :: :: :: *" ::: "^ '"-' ::: ": '"':"::\ ::::'*' ''''" <:'': *]; ^ A ;;
1F. ..... : -.-... .. .
.. . . .. ... .. ... ..... 9 .- .. . . ............. I ,, ,


In .... III ............. ........ ....................... ...............-
...... ........... .. ...........
,::::: ::::: ::!1 ; ,- .. .. 1. .. ... ...........::: ............ ..I ..........: : : b..- ,:- :..y =, .<
.... ... t ... J .... .. .. .... ... .............. j L: .. .... ..
,xv -- . 1. . . .. . . .... . . .. . . . . ... ,-, r%. . .. . . . .
.o :" 'f I[ ... .. ]i:::: ::ll ... ...........r.. .'' ' Ju .._- .. < v .. \ ".I
-. .--' ....: '- ..... P L:'",' ;::........:.:...... . . . . . .,'.-:'... .., ,r
I..' ,:,' :.";;- fa .. . -- . . ... . . -' ," ,"


































Figure 13.--Dispersal pattern of marked sterilized field-collected H.
pusio 96 hours following release.











.. . =; Release site

1 0 Traps collecting marked gnats
.. . . . '- ":"' : ?Traps collecting unmarked gnats
Si i==!i=~ ~i..........
S... .. .. .. . i i i = -
L ............ ..


============;==========;== .; i x ,.,-^o:;;; ^ ;!;"; ^ ;;; ^.. ^'" :"=^ ^:

5-:^ "'im :,;; ; -1 lF- :' ::;;: ii;;;;;:;C;^ ^
... ... .. FV ...ii...ii i ;i : := =.. ;: : : ,:: -,
oJ( o... .... .. ..... :b

.. ... ..- ...
............ -.. .. ........ ..
.; .... =i!" .,
.. . ... 17%. L 7 f : F.-........... -:* I = = := : .
- ... . . . ...



,. .. .... Al::: ... ..... ... ...... .I .. ........
.. .. .. .. .. ... ".L -,L:
-:, L. 3I ": _1 ,1 .. .
JL 77:71 777 rn
I .; . . . . . . . . . ... ...=.:: : = i . . . . . . ." "".... . . .

^ ^ ,t^< ::::::::::: : *::: :: : T : : :::-i:::::r *-,< i- ^ *T* *^ * : : : : : : : : ^:::."- ,,,'. : -" :'** A *-

".. . . . .... -E7 7| |1. . . | | | i i "l| | ,,
'.:L = :: =, "" : -..-,..... L. '...... . ..... . .. .. .
... ... ..... .... ..'r-'..- .. .-;. .- ....... ... .. '':: .. _...... .,,.



............., ..........
SI I ........... L ... ,
S- .......... ......... ... .. .... .
. . . I . . .I I . f L : = = = . . I t ., , ... > . . . . . .7 o l. . . .. = :.:. .".. .'.".: '" 1

...... ...... .... ..,.......-....:..-









The fourth release consisted of approximately 12,000 laboratory-reared

(F14o) eye gnats marked with arc yellow fluorescent dust. The air temper-

ature was 3h.h0 C and the average relative humidity for the week was hh.O

per cent. The wind velocity and direction was 6 miles per hour from the

SE.

The released adults reacted similarly to the F139 gnats used in the

second release.by not flying out of the cage until disturbed and also land-

ing on the personnel in the vicinity of the release site. This differs from

the other releases because when a trap collected marked gnats. the same

number of marked eye gnats were replaced in the population approximately

10 meters from the collecting trap.

The results of this dispersal test are given only for 2h and h8 hours,

since trapping after this period did not yield marked gnats. This release

displayed a very good dispersion pattern for 2h hours (Fig. lh) with the

greatest distance approximately 1650 feet (500 meters). Also, 19 of the

37 traps collected marked eye gnats. The results for h8 hours exhibited

a sharp decline in numbers with only h (Fig. 15) traps collecting marked

individuals.

The fifth release was made using 12,000 tepa sterilized field-collected

adults, 12,000 laboratory-reared (Flhl) adults and 12,000 laboratory-reared

(Fl) adults marked with fluorescent dust colored rocket red, horizon blue

and saturn yellow, respectively. The minimum relative humidity for the

week of the release was 62.h per cent with the air temperature at ground

level 32.20 C. The wind velocity was less than 1 mile per hour.

Due to heavy rains that lasted for 8 days, the results of this dis-

persal test are negligible. In most instances traps did not collect any

eye gnats and also some of the traps could not be checked daily because of


- 57 -




































Figure l1.--Dispersal pattern of marked laboratory reared (Fl1O) H. pusio
2h hours following release.













.- .c.C-t, . .,. O T..\ Release site
I "oPU ^^ A ; ,,^ Cb' .+ :,'T l -, 'aT.'.;*<'^-,. -*;-, a'q,- &'*t*<; '*^ '*., '"> -
tot.^ "t v.2i,.,+ .. Traps collecting marked gnats
**' s. ,,q, ,, '.* ,- '<' -c.' /' .' '+l/ ;,JM it~'l '-i +'." ,- 7*^ ';. +,'*,, - **_""* t+- l
^TY|yN^L: 'bt i:TTT1^3FU^iuu'.:, &A Traps collecting unmarked gnats
% .. g ".......... ....... t
S......::::::....:::::::::.::..

............ ............ .- 1

.. . + ',.1 .. _ 12,- ._ Z +, .'-." .. .....-.......,........ "

I
"" '", ,- L .' -,"I, II ... .... ...:ti........... '" ,> . +i t',. T s'- v, ,::. =. ta ,
i..?- : X ::-:::4~ ..... .........c 0.......


*A ^ ^ :::: : t:::::^ ?:?4I:.1..,r^.-^ ^^.-^ ^ ^L
I ., ... ... ... rI- .. .< .. ... , . .: ,:M ,.
...........
-i.:. ........ .... ..: .. . .


I -
, ........ .....,.. ....
",, ...' . .- '. .... . .. ."'
. . . . . ... & .. ..

.. . . ... r
f-1~I .7--
i".: r: : : [ : JL `D...... . ..... ............
.i,<, ...... .... .... r;. ,
....... I ....... ..... .... . ..-
fI ( .........j . I::::I'.. ...I. : : : .: :... :::::::::::.. :::::: : ::.: -, .

I| *:::::; : L'. L<: ;LLL.i :7 4i
:t.~~..... C '- 4fl7r.
47 k..;4*
.... .... ...,
S:::: : .... ........ ''
It-,+: ~ ~ ~~~~~~~~ .... ,... L... 1... ......:,...... J .... { ] .... .. I .... .. .. .., l






























Figure 15.--Dispersal pattern of marked laboratory reared (FlhO) H. pusio
h8 hours following release.











2-- (itr%-- .I v -77M -- ..- -

Release site

Ir,.'. Q =Traps collecting marked gnats

.i.....7.. :.T. .I Traps collecting unmarked gnats

IA t 7 . . . . . . . . .
'< i '::::::::::...... ... : :::: :: ,,
..:::::::::::::: : ::::::::::::: L ,
J. ...... .. .=.. .. .




... .............. .






S l ::' : : ::::::: :: d
t .' ..........- .. ..

.... ........ .. .. ... ... .. ... ...

L ., i L.- r.. ..... :: J J L ... ... .. .. . -. .
I... ...........................
S................. ......... .. .................. .
, , . . .. . .. I....... ..... ... t ::-I









'' 'r'." ':'';:,"*'? :: :: :::: ::: :: : : :: : :: : :: : :: : :: : :: : : ::: ::::::It.<'. '. ,,:,. ,* l







62 -


flooded conditions. However, one trap did collect a marked laboratory-

reared (Fll) eye gnat 11 days after the release was made. This release

was not repeated because of the limited time and assistance available to

the author.
















POPULATION DENSITIES



Population densities were measured by trapping field adult eye gnats

during a two-year period. Traps were usually operated for approximately

2 weeks in each month; however, the duration as well as the number of traps

set varied throughout the year. During the winter months when eye gnat

densities were extremely low few traps were operated. However, during the

summer months when populations were at a peak, large numbersof traps (as

many as 37 per day) were in operation.

All collecting was done at the University of Florida's horticulture

farm and the experiment station honey plant. These two areas are approxi-

mately 15 miles apart. The horticulture farm is the site of constant cul-

tivation whereas the honey plant area has limited cultivation and some

cattle grazing nearby. Comparisons were not made between the two areas in

population, densities because the horticulture area is much larger and more

extensively cultivated than the honey plant tract.

The adult field eye gnats were collected in a glass-funnel plastic

cylinder trap, shown previously (Fig. 1), using a mixture of putrefying

shrimp and water as the attractant. The traps were normally set on Mon-

day. Collection cylinders were returned to the laboratory daily and the

eye gnats were identified, sexed and counted. During the summer months

when large numbers of adults were collected, a random sample of 100 eye

gnats from each collection cylinder was identified and sex determined.

Collections numbering more than 1000 gnats were estimated by counting ali-


- 63 -






- 64 -


quot fractions.

A total of 320,252 field eye gnats was amassed during the period from

April 1967 through April 1969. H. pusio comprised 96 per cent of all eye

gnats collected at the horticulture farm and honey plant areas. Female

gnats made up 95.3 per cent while only 4.7 per cent of the total collection

were males. Thus, the data are confined to the female eye gnat.

In 1958, Dow and Hutson reported in Georgia that the majority of trapped

H. pusio obtained in population measurements were females, males averaging

less than 10 per cent of all collections. Jay (1961),using an aspirator

collected eye gnats crawling around a calf's eyes, on a child's face, on

his own face, and around the genital region of a dog. The total collection

contained 96 per cent females.

In the two areas sampled in this study, the highest densities of eye

gnats (58,000 to 66,000) occurred during the month of July for 1967 and

1968 (Fig. 16).

Reproductive Capacities

Tests using laboratory-reared female eye gnats were conducted to de-

termine their reproductive capacity. Ten 2 to 3 day old virgin females

were placed in 2 quart standard mason jars containing 10 males per jar and

food was made available. The containers were checked daily; eggs were re-

moved and seeded in larval media. The tests were continued until 100 per

cent female mortality occurred in all containers. Each cross was replicated

10 times.

The test lasted 38 days. A total of 4,.241 eggs were collected yield-

ing a mean of 42 eggs laid per female. The majority of c.: were :-.-itcd

10 to 12 days after the females had emerged from the pupal cases. The per

cent of adult emergence from these eggs was extremely low--18.7; however,








































AMJJ ASONDJ FMAMJ J ASON DJ F MA
1967 1968 1969

Monthly Measurements









Figure 16.--Population densities of the eye gnat H. pusio collected
in baited traps at the horticulture farm and honey plant
areas during a 2 year period.


- 65 -







66 -


this was probably due to a fungus that developed in the larval media. Fe-

male eye gnats oviposit continually beginning with approximately the fifth

day following emergence. There appears to be peaks of oviposition occurring

at the fifth, seventh, and eleventh days after emergence.















DISCUSSION


Previous studies on the eye gnat H. pusio involved certain aspects of

'the biology, ecology, and control of this species. Limited work was car-

ried out on sterilizing H. pusio using cobalt 60 gamma rays and certain

chemicals, the latter studies being histopathologically oriented. Thus,

it was decided to initiate chemosterilization studies which would lead to

a feasible and effective method of sterilizing eye gnats for possible

sterile-release programs. Since field- rather than laboratory-reared

populations would be used, the dispersion and density of the field strain

needed to be studied.

Chemosterilization of Eye Gnats

Of the three methods used to autosterilize the eye gnat, H. Pusio,

the method in which chemosterilant-treated polystyrene foam strands were

placed on anesthetized adults proved most effective. The highest per cent

sterility with the lowest per cent mortality was obtained using this pro-

cedure. If a method could be developed in the field whereby the eye gnat

might be attracted to an apparatus which would force the gnat to crawl

through a layer of treated foam strands in order to escape, then a tech-

nique of sterilizing the field gnat without removing it from the natural

population would be possible.

The method in which adult eye gnats were exposed to metepa residues

on nylon mesh screen gave good results when a 5.0 per cent solution was

used. When the concentration was increased to 10.0 per cent, the mor-


- 67 -







- 68 -


tality increased as expected. This method could also be of value when

used in a field control program. However, the per cent sterility obtained

would have to be higher than that obtained in the above method.

The autosterilizing method using newly closed adults migrating

through treated polystyrene foam strands showed very good sterility but

the mortality was too high for consideration as an effective method.

The per cent sterility in laboratory-reared H. pusio following ex-

posure to 5.0 per cent or 10.0 per cent metepa residues on nylon mesh

screen was slightly higher in tests using males. The higher the concen-

tration, the higher was the sterility and mortality obtained in both males

and females.

In all tests, when field-collected eye gnats were compared with

laboratory-reared gnats, the highest per cent sterility was obtained using

the former. Also, when a comparison was made between Fl and F135 laboratory-

reared eye gnats, the Fl adults showed the highest per cent sterility; how-

ever, mortality was also higher when using the Fl adults. Since the field-

collected eye-gnats are easier to sterilize than the laboratory strain, it

would appear to be more feasible to use the former rather than the latter

in a control program involving chemosterilants.

Studies were conducted on different-aged adults in order to determine

the elapsed time required for them to migrate through 15-centimctcr layer

of polystyrene foam strands. The two ages used were newly closed adults

and 2-to 3-day old adults. When the two ages were compared, the elapsed

time required by the newly closed adults was approximately 15 minutes

while that required by the 2-to 3-day old adults was approximately u

minutes, an 11 minute difference. This tine lag resulted in increased

mortality when the newly closed adults were exposed to chemostc.ilant







- 69 -


treated foam strands. Thus, when different-aged adults are exposed to the

same concentrations, the exposure time is an important factor. Generally,

the longer the exposure time, the higher will be the mortality.

In multiple mating tests using laboratory-reared H. pusio, the female

was shown to be polygamous. Sperm in the initial mating probably remained

in the female. Thus, subsequent matings were diluted by the initially

deposited sperm. This was easliy seen when sterilized males were crossed

with untreated virgin females, these same females then crossed with un-

treated males, and this entire sequence reversed.

Dispersal Tests

When four independent releases of adult female eye gnats were made,

the release using field-collected gnats dispersed farther and over a lar-

ger area than sterilized field-collected gnats or F139 and FlhO laboratory-

reared eye gnats. The untreated field-collected gnats also were trapped

in larger numbers over a longer period of time than the three types men-

tioned above. When tepa-sterilized, field-collected gnats were released,

though dispersion was not quite as far as the untreated field-sterilized

strain, their coverage of the immediate area and longevity was just as

great. It appears that sterilizing these eye gnats had little effect on

their dispersion. In releases using the F139 and FlhO laboratory-reared

eye gnats, dispersion results were inferior in all cases except those

obtained 2h hours following the release of the F140 strain. These gnats

displayed good coverage for 2h hours; thereafter the number of individuals

collected in traps decreased extremely fast. When the lh-hour results

were checked, only four traps had collected marked gnats and following

this time period no marked gnats were collected. This lasL fact sccms

exceptionally odd since,unlike the other releases, marked gnats werc rc-






- 70 -


placed in the population during this test. However, here is a good example

of the laboratory-reared insect behaving differently than the field species.

The F139 strain persisted slightly longer than the FlhO but exhibited poor

dispersion throughout the test.

In a fifth release using sterilized field-collected Fl and F140

laboratory-reared eye gnats, the results were not considered because of

heavy rains.

Population Density Studies

By using the number of marked eye gnats released and the total numbers

of marked and unmarked gnats collected, one can estimate the population

density of the insect in a given area. Of course, these estimations in-

clude some uncertainties, such as, migration in and out of the area sampled

and mortality of marked gnats after the release. Also, many assumptions

must be made in all capture-recapture methods of estimating population

parameters (Southwood, 1966) and this study was not an exception.

An estimate of the population density of eye gnats at the horticulture

farm was calculated using the Lincoln index (Le Cren, 1965) in which the

total population is equal to the number of marked individuals multiplied

by the number of individuals recaptured, divided by the number of marked

individuals recaptured.

Since both laboratory-reared and field-collected adults were released,

it is reasonable to assume that the field-collected data would give the

best indication when estimating population densities for the area surveyed.

As the results are given for four different time periods (24, 68, 72 and

96 hours), the time when the largest per cent of marked gnats wcre cap-

tured probably indicates reasonable approximations for the area surveyed.

In the results shown in Table 10, both 2h-hour periods yielded the
/






- 71 -


Table 10.--Population density of the eye gnat H. pusio calculated from
collections of marked and unmarked gnats at the horticulture
farm. The area surveyed was 527 acres.


Release of 12,000 Field-collected Adults

Hours Total No. Total No. and Total gnat Density
following gnats per cent of population of gnat
release captured marked gnats calculated- population
captured (gnats / acre)


No. %
24 8,599. 69 .56 1,495,478 2,838

48 ,,455 18 .15 2,970,000 5,635

72 2,596 18 .15 1,730,666 3,284

96 2,459 11 .09 2,682,544 5,090


Release of 12,000 Sterilized Field-collected Adults

24 2,569 28 .23 1,101,000 2,089

48 2,887 22 .18 1,574,727 2,988

72 2,416 5 .oh 5,798,400 11,002

96 3,528 7 .05 6,0o6,.71 11,73

-Calculated using the Lincoln Index.






- 72 -


highest per cent of marked gnats captured. The data for total population

and density of gnats per acre are quite similar. The time period showing

the next highest per cent of marked gnats captured is the hS-hour period

when only sterilized, field-collected adults were released. The results

shown for this period are also similar to the two 2h-hour periods.

The data from the four time periods using field-collected adults that

were not sterilized yielded a mean of 2,21h,67h gnats for the total popu-

lation and a density of h,212 gnats per acre.

When the mean is calculated for both sterile and fertile eye gnat

releases using the 2h-hour collection periods, the total population is

1,298,239 gnats for the 527 acres and the density is 2,468 gnats per acre.

The estimation of the total population from the 2h-hour time period

may be low due to the inadequate mixing of marked and unmarked populations.

Furthermore, the estimation for the 96-hour period may be high due to the

movement of gnats out of the surveyed area and to the natural mortality

of the gnats. If the above statements are considered true then the esti-

mates for the h8 hour and 72 hour periods should be fair approximations

of the total population density of the eye gnats for the area surveyed.

Since the sterilized field-collected adults had an extremely low per

cent of captured marked adults, only the mean from h8-and 72-hour results

using the fertile field adults was calculated. These averages were

2,350,333 gnats for the total population with a density of h,459 gnats

per acre.

When the results using the Lincoln index as a means of csti.;mtion are

observed overall, the total population of eye gnats for the 527 acres was

1 to 3 million,with the density at 2 to 5 thousand gnats per acre. These

estimates appear low for 527 acres, but it must be mcntioncd that only







- 73 -


260 acres were under cultivation and the remaining portion was woodlancd.

Eye gnats do not occur in great numbers in heavily wooded areas. So xany

assumptions are involved, one must not overlook this fact when consider-

ing the usefulness of the above data.

When reproductive tests were carried out using laboratory-reared fe-

male eye gnats, a mean of h2 eggs per female was laid with the major depo-

sition period occurring between the tenth and twelfth day following eclo-

sion. If 70 per cent of the approximately h200 eggs hatch, then 2900 anats

are produced in the second generation with half (1h70) of them being fe-

males. If these 1h70 females deposit an average of h2 eggs per female, a

total of 61,740 eggs are laid. When 70 per cent of these eggs hatch, the

total eye gnat production in the third generation is 43,218 with 21,609

females. Projecting these increases on a large scale, one is able to

understand why the population densities of eye gnats can be so high.















SUMMARY AND CONCLUSIONS


Adult males and females of H. pusio were sterilized with metepa and

tepa using contact methods of application. The males of H. pusio were

sterilized after being placed in holding jars containing a baited cup

covered with 5.0 per cent metepa treated screen. Males showed a higher

per cent sterility than females when both sexes were exposed to 5.0 per

cent and 10.0 per cent metepa residues on nylon mesh (32 x 32). screen.

Adult field-collected H. pusio yielded a higher per cent sterility

and mortality when compared with 2-to 3-day old laboratory-reared eye

gnats. When both Hippelates strains were exposed to 5.0 per cent and 10.0

per cent metepa residues on nylon mesh screen, the laboratory-reared

adults proved more difficult to sterilize and less susceptible to the

toxicity of the chemosterilant.

An autosterilization technique developed for the house fly proved to

be feasible and very successful on the eye gnat H. pusio. When two gen-

erations (Fl and F135) of pupae were covered with a 10-centimeter layer

of 5.0 per cent tepa or metepa treated polystyrene foam strands, the newly

closed adults were sterilized upon migrating upward through the treated

foam strands. The F1 adults indicated a higher per cent sterility than

the F135 adults. Tepa yielded the highest per cent sterility with mctcpa

yielding the lowest per cent mortality. By increasing the thickness of

the layer of treated polystyrene foam strands used in the autostcriliaa-

tion technique from 10 centimeters to 15 centimeters, the sterility was


- 7h -









increased to 100 per cent using tepa or metepa; however, the per cent mor-

tality was also increased. The highest per cent sterility with the lowest

per cent mortality was obtained with the autosterilization technique when

field-collected and laboratory-reared H. pusio adults were anesthetized

with carbon dioxide, allowed to recover and crawl upward through a 1i-centi-

meter layer of treated polystyrene foam strands. This method was by far

the most effective of the autosterilizing methods used. Both tepa and

metepa gave the highest per cent sterility when using field-collected adults

and lowest per cent mortality when using laboratory-reared adults.

The mean elapsed time required for newly closed adults and anesthe-

tized adults to crawl upward through a 15-centimeter layer of foam strands

was found to be 15 minutes 2h seconds and h minutes 26 seconds, respectively.

The longer time required by the newly closed adults to migrate through the

foam resulted in higher mortality.

Results of multiple mating tests involving males sterilized with metepa

indicated that the female H. pusio is polygamous with a carry-over of

sperm from the initial mating.

The use of micronized fluorescent dust to mark both field-collected

and laboratory-reared adult H. pusio for dispersal studies had little

effect on longevity and was detectable throughout the life of the eye

gnat. When field-collected, sterilized field-collected, and laboratory-

reared adults of H. pusio were marked, released, and recapture, the dis-

persion of the field-collected adults was much greater than that of the

laboratory-reared gnats. This shows that in any test where good disper-

sion of eye gnats in the natural population is required, the field ndult

would be the feasible strain to use. Sterilizing the ficed-collected

adults had very little effect on their dispersion. The farthest distance


- 75 -






- 76 -


traveled by a released marked eye gnat was approximately 3630 feet (1100

meters). The greatest number of days following the release that a marked

eye gnat was collected was 11 days.

During the 2 year period of population density studies, a total of

320,252 field adult eye gnats was collected in shrimp baited traps. Fe-

males made up 95.3 per cent and males h.7 per cent of the adults collected.

H. pusio comprised 96 per cent of the total collection. The densities of

eye gnats were highest in the months of June through August,with the peak

occurring during July of both years. The population density of H. pusio

was calculated from collections of marked and unmarked eye gnats released

over a 527 acre area. The gross observations of data from field-collected

adults indicated the total population as 1 to 3 million for the entire

area with a density of 2 to 5 thousand eye gnats per acre.

The reproductive capacity of the laboratory-reared H. pusio was 42

eggs per female, with the peak production occurring 10 to 12 days follow-

ing eclosion. The female eye gnat oviposits continuously throughout its

life; however, egg production declines as age of the female increases.













LITERATURE CITED


Abbott, W. S. 1925. A method of computing the effectiveness of an in-
secticide. J. Econ. Entomol. 18: 265-267.


Andrewartha, H. G. 1961.
University of Chicago


Introduction to the study of animal populations.
Press, Chicago. 281 p. '


Auerbach, C. and J. M. Robson. 19h7. The production of mutations by chem-
ical substances. Proc. Roy. Soc. Edinburgh 62: 271.


Bassett, D. C. J.
cet. 1: 503.


1967. Hippelates flies and acute nephritis. The Lan-


Bigham, J. T. 1941. Hippelates (eye gnat) investigations in the south-
eastern states. J. Econ. Entomol. 34: 439-1W4.

Bird, M. J. 1950. Production of mutations in Drosophila using four aryl-
2-halogenoalkylamines. Nature. 165: 491-492.

Blanco, L. and P. Soberon. 1944. Las moscas del genero Hippelates como
posibles vectores del mal del pinto (2a comunicacion). Ciencia.
4: 299-300.


Borkovec, A. B. 1966. Insect chemosterilants, p. 1 to 143.
in pest control research, volume 7. John Wiley and Sons,


In Advances
New York.


Clark, L. R., P. W. Grier, R. D. Hughes, and R. F. Morris. 1967. The
ecology of insect populations in theory and practice. Methuen and
Co., Ltd., London. 232 p.

Dow, R. P., and G. A. Hutson. 1958. The measurement of adult populations
of the eye gnat, Hippelates pusio. Ann. Entomol. Soc. Amer. 51: 351-360.

Dow, R. P. 1959. Dispersal of adult Hippelates pusio, the eye gnat.
Ann. Entomol. Soc. Amer. 52: 372-381.

Flint, H. M. 1964. The effect of cobalt 60 gamma rays on the biology of
the eye gnat Hippelates pusio Loew. Doctoral Dissertation, University
of Florida.


Fye, R. L.,
ment of
Entomol.


C. LaBrecque, P. B. Morgan, and M. C. Bowman. 1968. Develop-
iautosterilization technique for the house fly. J. Econ.
61: 1578-1581.


Herms, W. B. 1926. Hippelates flies and certain other pests of the
Coachella Valley, California. J. Econ. Entomol. 19: 692-695.


- 77 -






- 78 -


Jay, E. G. Jr. 1961. Laboratory and field studies of the ecology of
Hippelates pusio, Loew. (Diptera: Chloropidae) and related species.
Master's Thesis, University of Florida.
/
Knipling, E. F. 1959. Sterile male method of population control. Science.
139: 902-904.

Kumm, H. W., and T. B. Turner. .1936. The transmission of yaws from man to
rabbits by an insect vector, Hippelates pallipes Loew. Am. J. Trop.
Med. 16: 245-262.

LaBrecque, G. C., P. H. Adcock, and C. N. Smith. 1960. Tests with com-
pounds affecting house fly metabolism. J. Econ. Entomol. 53: 802-805.

LaBrecque, G. C. 1961. Studies with three alkylating agents as house fly
sterilants. J. Econ. Entomol. 54: 684-689.

LaBrecque, G. C., and C. N. Smith. 1968. Principles of insect chemosteri-
lization. Appleton-Century-Crofts, New York. 354p.

Le Cren, E. D. 1965. A note on the history of mark-recapture population
estimates. J. Anim. Ecol. 34: 453-454.

Mulla, M. S., and R. B. March. 1959. Flight range, dispersal patterns
and population density of the eye gnat, Hippelates collusor. Ann.
Entomol. Soc. Amer. 52: 6h1-646.

Mulla, M. S. 1968. Chemosterilants for control of reproduction in the
eye gnat (Hippelates collusor) and the mosquito (Culex quinquefascia-
tus). Hilgardia. 39: 297-325.

Roberts, R. H. 1968. A feeding association between Hippelates (Diptera:
Chloropidae) and Tabanidae on cattle: Its possible role in trans-
mission of anaplasmosis. Mosquito News. 28: 236-237.

Ruff, J. P. 1967. Study of attractants and traps for eye gnats (Hippelates
pusio Loew). Master's Thesis, University of Florida.

Sanders, D. A. 1940. Musca domestic and Hippelates flies, vectors of
bovine mastitis. Science. 92: 266.

Scherer, L. E. 1963. Ecological studies of the eclosion and development
of the eye gnat Hippelates pusio Loew (Diptera: Chloropidac). Mas-
ter's Thesis, University of Florida.

Schwartz, P. H. Jr. 1964. Reproduction and chemical sterilization of the
eye gnat, Hippelates pusio Loew. Doctoral Dissertation. University
of Florida.

Smith, C. N., G. C. LaBrecque, and A. B. Borkovec. 1964. Insect chemo-
sterilants. Ann. Rev. Entomol. 9: 269-284.

Southwood, T. R. E. 1966. Ecological methods with particular reference
to the study of insect populations. Meuthuen and Co., Ltd. London.-
391p.






79 -


Steiner, L. F. 1965. A rapid method for identifying dye-marked fruit
flies. J. Econ. Entomol. 58: 374-375.

Turner, E. R. 1960. Certain aspects of the biology and control of the
eye gnat, Hippelates pusio Loew. Master's Thesis, University of
Florida.

Turner, R. B. 1968. Chemistry of insect chemosterilants, p. 159 to 27h.
In G. C. LaBrecque and C. N. Smith (ed.) Principles of insect cheno-
sterilization. Appleton-Century-Crofts, New York.
















BIOGRAPHICAL SKETCH


David F. Williams was born September 4, 1938 at New Orleans. Louisiana.

He attended Lopez Elementary and Notre Dame Junior High School in Biloxi,

Mississippi and was graduated from Notre Dame Senior High School in ,

1956. He enlisted and served in the United States Navy for thirty-nine

months. Upon being honorably discharged, he enrolled in the University

of Southwestern Louisiana in September, 1959. He received the Bachelor

of Science degree in Biology in August, 1963 and was then employed by

Wyeth Laboratories. He resigned and enrolled in the Graduate School of

the University of Southwestern Louisiana in February, 196h. Upon receiv-

ing the Master of Science degree in August, 1966, he enrolled in the Grad-

uate School of the University of Florida. From September, 1966 until the

present time he has been a Research Assistant while pursuing the degree

of Doctor of Philosophy.

David F. Williams is married to the former Sylvia Gail Smith and has

one daughter, Andrea Elizabeth.

He is a member of the Entomological Society of America, the Florida

Entomological Society and past officer of the Newell Entomological Society.


- u0 -














This dissertation was prepared under the direction of the chairman

of the candidate's supervisory committee and has been approved by all

members of that committee. 'It was submitted to the Dean of the College

of Agriculture and to the Graduate Council, and was approved as part:7";

fulfillment of the requirements for the Degree of Doctor of Philosophy


August, 1969



I4JDean, College of Agriculture



Dean, Graduate School


Supervisory Committee:



Chairman

t.7 20



-ic5f cfiAa^^






Internet Distribution Consent Agreement


In reference to the following dissertation:


AUTHOR: Williams, David
TITLE: Chemosterilization dispersion and population densities of the eye gnat
Hippelates pusio Loew / (record number: 431401)
PUBLICATION DATE: 1969




I, Ti'16/ / / //9 as copyright holder for the aforementioned dissertation,
hereby grant specific and limited archive and distribution rights to the Board of Trustees of the University of
Florida and its agents. I authorize the University of Florida to digitize and distribute the dissertation described
above for nonprofit, educational purposes via the Internet or successive technologies.

This is a non-exclusive grant of permissions for specific off-line and on-line uses for an indefinite term. Off-line
uses shall be limited to those specifically allowed by "Fair Use" as prescribed by the terms of United States
copyright legislation (cf, Title 17, U.S. Code) as well as to the maintenance and preservation of a digital archive
copy. Digitization allows the University of Florida or its scanning vendor to generate image- and text-based
versions as appropriate and to provide and enhance access using search software.

Tbis grant of permission pr ibits use of the digitized versions for commercial use or profit.


1 "Siature 6f Copyright Holder


Printed or Typed Name of Copyright Holder/Licensee


Personal information blurred

*


Date of Signature

Please print, sign and return to:
Cathleen Martyniak
UF Dissertation Project
Preservation Department
University of Florida Libraries
P.O. Box 117008
Gainesville, FL 32611-7008




University of Florida Home Page
© 2004 - 2010 University of Florida George A. Smathers Libraries.
All rights reserved.

Acceptable Use, Copyright, and Disclaimer Statement
Last updated October 10, 2010 - - mvs