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MANAGEMENT OF PEST MOLE CRICKETS USING THE INSECT PARASITIC
NEMATODE Steinernema scapterisci
KATHRYN ANN BARBARA
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
Kathryn Ann Barbara
This dissertation is dedicated to my family, Kathleen and Jack Barbara, Anthony, Lara,
and Elizabeth Barbara, Lisa, Eric and Ryan Malkowski, Anne Barbara, Ann and
Raymond Callahan, John Michael, Kathleen, Melinda, and Maureen Gowdey, Camilla
Barbara, James Dunford, and Magnum, the delightful Doberman. Without their love,
thoughtfulness and support this would not have been possible.
My heartfelt thanks go to my major advisor, Dr. Eileen Buss. Her guidance,
advice, and trust have made this research possible. Dr. Buss has been a mentor in not
only my academic life but my personal life as well. I consider myself lucky to have been
her first Ph. D. student. I would also like to thank my committee members, Drs. J.
Howard Frank, Norman C. Leppla, Grady L. Miller, and especially Khuong B. Nguyen,
who has given me the knowledge about nematology to make my degree truly a work of
entomology and nematology. I could not have had a better committee. Each has
contributed significantly to this work and it would not have been possible without each
and every member.
This research would not have been possible without the help of many people. I
would like to thank the cooperators and their assistants who allowed me to use their sites
and were very helpful during my research. Special thanks go to Buddy Keene II, Lloyd J.
Brown and Diane Delzell from Gainesville Golf and Country Club; Dave Carson, Kevin
Cooke, and Vern Easter from Ironwood Golf Course; Fred Santana from Sarasota County
Extension; and Matt Burke from the City of Altamonte Springs. Nematodes and advice
on their use were provided by Tom Hinks, Gabe Diaz-Saavedra, and Al Clarke from
Becker Underwood and Martin Adjei of the Ona Range Cattle REC. I acknowledge Dr.
Tom Walker for mole cricket advice and assistance.
I acknowledge Dr. Albrecht Koppenhofer from Rutgers University for technical
advice and methodology for the pesticide compatibility tests. Special thanks go to John
Fredricks for help with soil sample analysis, Marinela Capanu for help with statistical
design and analysis, and Paul Skelley (DPI) for help with SEM photographs. I
acknowledge Bayer Environmental Science, Valent Professional Products, and FMC
Corporation for donating insecticides used in this study. Special thanks go to Brian
Owens at the G. C. Horn Memorial Turfgrass Field Laboratory for his assistance and
patience with setting up nightly collections with mole cricket sound callers. Angela
Vincent and Shubin Saha assisted in sorting linear pitfall trap samples. I would also like
to acknowledge the electronic thesis and dissertation technical staff for their help in
formatting and submission of my dissertation. Many thanks go to the Florida Department
of Agriculture and the United States Navy for graduate funding.
Very special thanks go to the numerous people who helped in my various projects;
without them this project would not have been possible. First I would like to thank Paul
Ruppert for his assistance in numerous aspects of this study and his patience with me. I
also would like to thank Bob Hemenway for rearing supplies, guidance and advice. My
gratitude goes to Matthew Stanton and Y. Mike Wang for help with bi-weekly pitfall trap
collections and mole cricket rearing. I thank J. Cara Congdon, Jay Cee Turner, Lois
Wood, Rebecca Baldwin, Erin Finn, Alejandro Arevalo, Justin Emerson and Brian
McElroy for assistance in pitfall trap installation and removal. Special thanks go to
Robert Mans and Rachel Davis for help with mole cricket rearing and the dreaded curfew
field test. Many thanks go to the University of Florida Entomology and Nematology
Department for their support and friendship through the years.
Several people I have met along this journey have become more than just my
academic and professional peers but have become very good friends. I want to give
special thanks and warm gratitude to J. Cara Congdon and Jay Cee Turner who, while
helping me become a better scientist by looking towards me for guidance and advice,
have become two of my best friends. I am especially grateful to James Dunford. He has
inspired me in all aspects of my life and several ideas in this dissertation were inspired
and motivated by him. Jim has given me the opportunity to discover other aspects of
entomology outside of my field. My only regret is that I did not meet him sooner.
TABLE OF CONTENTS
A C K N O W L E D G M E N T S ................................................................................................. iv
L IST O F T A B L E S .............. ................................................... ............... x.. ... ......x
LIST OF FIGURES .. ................... ............ ........ .............. xii
A B S T R A C T .................................................................................................................... x iii
1 INTRODUCTION AND REVIEW OF LITERATURE ................... ..................... 1
M o le C ric k e ts ................................................................................................................ 1
M anagem ent Practices .................................................. .............. ...............4...
C h em ical C control ... .. ........................................... ........................ .... ......... ... 4
N on-C hem ical C control ................. .............................................................5......
B biological C control ........................................................................................ .. .5
Insect Parasitic N em atodes................................... ...................... ...............6......
O b je ctiv e s ............................................................................................................... .. 1 0
2 ESTABLISHMENT AND SPREAD OF Steinernema scapterisci ON FLORIDA
G O L F C O U R S E S ....................................................................................................... 12
M materials and M ethods .. ..................................................................... ............... 13
S tu d y S ite s ........................................................................................................... 1 3
M ole C ricket M monitoring ....................................... ...................... ............... 13
L ab oratory A ssay ... ... ......................................... ....................... .......... 15
Statistical A analysis .............. .................. .............................................. 15
R results and D discussion ............................ .......................................... 15
3 SURVIVAL AND INFECTIVITY OF Steinernema scapterisci AFTER CONTACT
WITH SOIL DRENCH SOLUTIONS ..................................................................25
M materials and M ethods ............................................ ........................... ................ 27
N em atodes and M ole C rickets........................................................ ................ 27
B io a ssa y .......................................................................................................... 2 7
Statistical A naly sis .............. ...... ............ .............................................. 30
R results and D discussion ............................ .......................................... 30
4 INTEGRATION OF INSECT PARASITIC NEMATODES WITH INSECTICIDES
FOR CONTROL OF PEST MOLE CRICKETS ............................. ..................... 36
M materials an d M eth o d s ............................. ......... ....... .......... ........................................3 7
Survival and Infectivity of S. scapterisci After Exposure to Pesticides..............38
Nematode Infectivity After Exposure to Pesticide Treated Mole Crickets .........39
Statistical A analysis .............. .... .............. ................................................ 40
R results and D discussion ................ .............. ............................................ 40
5 EFFECT OF Steinernema scapterisci NGUYEN AND SMART EXPOSURE ON
MOLE CRICKET TUNNELING, OVIPOSITION, AND AVOIDANCE
B E H A V IO R ................................................................................................................ 4 6
M materials an d M eth o d s ......................................................................... .... ................ 4 7
Nematode Infection and Nematode Treated Areas Effect on Mole Cricket
Tunneling B behavior ... ...... ............. ...... ................ ... ............... 48
Oviposition Behavior of Mole Crickets Exposed to S. scapterisci ..................50
Y -T u b e T e sts ....................................................................................................... 5 0
O b servation C ham b er................................................................. ............... 50
Response to S. scapterisci or Pesticides.................................. ................ 51
Statistical A analysis .............. .................. .............................................. 52
R e su lts ............................ ................................................................ ...... ..................... 5 2
Nematode Infection and Nematode Treated Areas Effect on Mole Cricket
T unneling B ehavior98 ........................................................... ... ................ 52
Oviposition Behavior of Mole Crickets Exposed to S. scapterisci.................. 53
Y -T u b e T e sts ....................................................................................................... 5 3
D isc u ssio n ............................................................................................................... ... 5 4
6 SUM M ARY AND CONCLU SION S.................................................... ................ 61
A AMBIENT DATA AND TURFGRASS QUALITY DATA COLLECTED AT
GAINESVILLE GOLF AND COUNTRY CLUB AND IRONWOOD GOLF
C O U R S E ..................................................................................................................... 6 3
B DATA FROM ATHLETIC FIELD DEMONSTRATION SITES.............................66
M materials an d M eth o d s ...............................................................................................6 6
O objective ............................................................................. .......... ............... 66
S tu d y S ite ............................................................................................................. 6 6
M ole C ricket M monitoring ....................................... ...................... ................ 66
R results and D discussion ................ .............. ............................................ 68
C PRELIMINARY CHECKLIST OF ARTHROPODS ASSOCIATED WITH GOLF
C O U R SE T U R F G R A S S ............................................................................................7 1
D SCANNING ELECTRON MICROGRAPH PICTURES OF MOLE CRICKET
SE N S O R Y A R E A S ....................................................................................................7 3
L IST O F R E F E R E N C E S ...................................................................................................76
BIO GR APH ICAL SK ETCH .................................................................... ................ 87
LIST OF TABLES
2-1. Percent infection of Scapteriscus spp. mole crickets collected from sites treated with
Steinernem a scap terisci .......................................... ......................... ................ 24
3-1. Mean nematode mortality and percent of mole crickets infected with Steinernema
scapterisci after exposure for 24 h to various drenching solutions.......................34
3-2. Mean nematode mortality and infectivity after exposure for 24 h to various
drenching solutions. ............................ ............................................ 34
3-3. Mean number of mole crickets emerging from bermudagrass using various
drenching solutions in M ay 2003 ....................................................... ................ 35
3-4. Percent nematode infection from mole crickets exposed to treatment solutions 1, 5,
8, 12, or 24 h post infection ................................... ....................... ................ 35
4-1. Percent survival, infectivity, and days until death of S. scapterisci incubated in
solutions of insecticides for 24 h ......................................................... ................ 44
4-2. Average days until death and percent infectivity by S. scapterisci nematodes to mole
crickets exposed to insecticides........................................................... ................ 45
5-1. Oviposition of Scapteriscus mole crickets directly infected with different numbers
o f S scap terisci. ....................................................................................................... 5 9
5-2. Oviposition of Scapteriscus mole crickets in sand treated with S. scapterisci.......... 59
5-3. Response of Scapteriscus vicinus, S. borellii, and S. abbreviatus to Steinernema
scapterisci nem atodes versus sterilized sand. ..................................... ................ 59
5-4. Response of Scapteriscus vicinus to Steinernema scapterisci nematodes versus
pesticides treated sand .. ................................................. ............ 60
A-1. Ambient data collected from Gainesville Golf and Country Club on dates of mole
crickets collections. ........... ... .............. .... ........ ...... ............... 63
A-2. Ambient data collected from Ironwood Golf Course on dates of mole crickets
c o lle ctio n s ............................................................................................................ .. 6 4
A-3. Average turfgrass density ratings for treated and untreated plots on Gainesville Golf
and Country Club and Ironwood Golf Course. ................................... ................ 65
LIST OF FIGURES
2-1. Linear pitfall trap used to collect m ole crickets. .................................. ................ 21
2-2. 3.8 L catch bucket inside 19 L bucket of linear pitfall trap..................................21
2-3. Mean monthly percent infection of mole crickets collected in pitfall traps at
Ironwood Golf Course from areas treated with Steinernema scapterisci ............22
2-4. Mean monthly percent infection of mole crickets collected in pitfall traps at
Gainesville Golf and Country Club from areas treated with Steinernema
sc ap te risc i................................................................................................................ 2 3
5-1. Distance tunneled through sand in Plexiglas arenas every 2 d by mole crickets
exposed to varying am ounts of nem atodes. ........................................ ................ 57
5-2. Comparison of total tunnel distances by male and female Scapteriscus spp. mole
crickets after exposure to S. scapterisci .............................................. ............... 58
5-3. Distance tunneled by mole crickets through sand treated with nematodes and
untreated sand in Plexiglas arenas over 48 h....................................... ................ 58
B-1. Average monthly infection rates at the Sarasota athletic field research site .......... 69
B-2. Average monthly infection rates at the Altamonte Springs athletic field research
site ........................................................................................................ ........ .. 6 6
D-1. SEM photograph of a female Scapteriscus vicinus antennal mid-section.............73
D-2. SEM photograph of a male Scapteriscus vicinus antennal mid-section...................74
D-3. SEM photograph of a female Scapteriscus vicinus mid-tarsal claw.........................74
D-4. SEM photograph of a female Scapteriscus vicinus labial palpomere.......................75
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
MANAGEMENT OF PEST MOLE CRICKETS USING THE INSECT PARASITIC
NEMATODE Steinernema scapterisci
Kathryn Ann Barbara
Chair: Eileen A. Buss
Major Department: Entomology and Nematology
Steinernema scapterisci Nguyen and Smart nematodes became established on two
golf courses in Gainesville, FL, when applied as an augmentative application, and moved
to untreated areas. It took about 4-8 wk post application for infection of mole crickets
(Scapteriscus spp.) to equal or exceed pretreatment levels. Infection levels in untreated
areas at least 80 m away from treated areas reached infection levels similar to the treated
areas in approximately 20 wk post application.
After a nematode application, mole crickets are frequently assayed to confirm
nematode establishment. However, the standard soap flush was suspected of providing
false negatives under field conditions. Thus, we examined the effect of several potential
flushing solutions on the survival and infectivity of S. scapterisci as well as flushing
ability under field conditions. Seventy percent of S. scapterisci died in the lemon dish
detergent solution, confirming that assays for nematode infection of soap-flushed mole
crickets are likely to be inaccurate. When sampling for mole crickets in areas where S.
scapterisci has been applied, a potential alternative to the standard soap drench is a dilute
Aqueous solutions of pesticides (acephate, bifenthrin, deltamethrin, fipronil and
imidacloprid) used in turfgrass to control mole crickets were tested for compatibility with
S. scapterisci in the laboratory. Survival of S. scapterisci was >95% in solutions of
acephate, bifenthrin and imidacloprid. Infectivity of S. scapterisci previously exposed to
insecticides was >60% in acephate and bifenthrin; however, infectivity was <40% in
imidacloprid. The entomopathogenic nematode was compatible with all insecticides
Both healthy and nematode-infected mole crickets had similar tunneling behavior.
Although not significant, crickets treated with 500 or 10,000 nematodes tunneled less
than uninfected crickets. Mole crickets did not appear to differentiate between untreated
and nematode-treated sand. Female crickets infected with nematodes were able to lay
eggs, and clutch size and egg chamber size were not significantly different than healthy
crickets. Crickets also laid eggs in sand treated with nematodes, suggesting that the
nematode treated sand was not a deterrent. Mole crickets in Y-tube tests did not
significantly choose untreated sand over sand treated with 500 or 10,000 nematodes.
When given a choice between field rates of S. scapterisci and acephate, bifenthrin,
deltamethrin, fipronil, or imidacloprid, crickets significantly chose nematodes over
INTRODUCTION AND REVIEW OF LITERATURE
Exotic mole crickets (Scapteriscus spp.) are the most injurious insect pests of golf
courses, lawns, sod farms and pastures in Florida and throughout the southeastern United
States (Walker and Nickle 1981). Mole crickets damage turf by tunneling in the soil
which exposes and dries out roots and by direct root feeding. As a result, the turfgrass
thins and bare patches appear. Weeds may invade these patches, leading to increased
herbicide use. The tunneling and mounds that mole crickets make also disrupt the
playing surface on golf courses, especially the roll of the golf ball on greens.
Superintendents and golf course members typically have zero tolerance for damage
(Frank and Parkman 1999). Insecticide treatments are usually targeted against the most
destructive nymphal stages (Parkman and Frank 1996, 1998). Mole cricket damage and
cost of control in Florida in 1986 were estimated at $45 million with an additional $33
million in Alabama, Georgia, and South Carolina combined (Frank and Parkman 1999).
Estimates of annual expenditure on chemical insecticides are over $18 million in Florida
turf, and over $12 million in control costs (Hudson et al. 1997).
Mole crickets are omnivorous, feeding on animal as well as plant material. Studies
have indicated that the southern mole cricket, Scapteriscus borellii Giglio-Tos, is less
damaging than the tawny mole cricket, Scapteriscus vicinus Scudder. Scapteriscus
borellii is a predator and feeds mostly on other insects while S. vicinus is mainly
herbivorous (Matheny 1981, Matheny et al. 1981, Walker and Dong 1982). Dissection of
field trapped S. borellii showed that their gut contents contained 66% animal material and
only 2% of plant material, and the rest a combination of plant and animal material. In
contrast, 84% of the gut contents of the short-winged mole cricket, Scapteriscus
abbreviatus Scudder, and 88% of S. vicinus contained plant material (Hudson 1985).
Both S. vicinus and S. borellii are pests of tomato and strawberry fields in Florida
(Schuster and Price 1992), as well as many vegetables, peanut, sugarcane, tobacco, and
ornamentals such as coleus, chrysanthemum, and gypsophila. Among turfgrasses, S.
vicinus often injures bahiagrass and bermudagrass, whereas S. abbreviatus favors St.
Augustinegrass and bermudagrass. Mole crickets also feed on weeds such as pigweed
and Amaranthus spp. (Capinera and Leppla 2001).
There are ten mole cricket species in the continental United States, Hawaii, Puerto
Rico, and the Virgin Islands (Frank et al. 1998). All mole cricket species are not pests.
Most species are innocuous and some are rare. For example, in Britain Gryllotalpa
gryllotalpa (L.) has become so rare that efforts to reintroduce it to mainland England
have been proposed (Spinney 1995). In the United States the prairie mole cricket,
Gryllotalpa major Saussure, feeds on prairie vegetation and is restricted to four central
states due to habitat loss, though it once had a much wider distribution (Vaughn et al.
1993, Frank et al. 1998).
Mole crickets primarily live underground in excavated tunnels. The forelegs of the
mole cricket are flattened and expanded, enabling it to burrow quickly in sandy and
extremely dry soils. Mole crickets form vertical tunnels as well as horizontal galleries
just below the soil surface. Mole crickets usually occur in the top 20-25 cm of soil and
have been recorded to tunnel as deep as 75 cm (Hudson 1985). The depth of mole cricket
tunneling varies with temperature and moisture. Galleries made by the crickets can be
used as an indication of their presence in the turf. Adults and large nymphs occasionally
move about on the soil surface on warm nights with high humidity and are often attracted
Male mole crickets produce loud songs (50-90 dB) after sunset by rasping a
stridulatory file on the forewing. Males use a funnel-shaped opening at the mouth of a
subterranean calling chamber, which amplifies the sound of their song. Calling chambers
are constructed each evening 10-20 min. before calling. The male mole cricket then
tunes these chambers to the frequency of his song (Forrest 1985), and calling lasts for
approximately 1 h after sunset. Songs function to attract flying and walking females.
The male's song intensity varies depending on male size and soil moisture (Forrest 1985).
The following information on the mole cricket life cycle was determined by Walker
(1985) and Frank and Parkman (1999). Adult S. vicinus fly in large numbers in early
spring, typically in March, but as early as February in Florida after warm winters. In
early summer, mole crickets mate (although some mating occurs the previous autumn),
and oviposit one or more clutches of 25-60 eggs. Females mate with males for < 24 h,
lay one or more egg clutches within 10-14 d after mating and then die. Eggs mature
within 3 wk in an incubation chamber in the soil. Nymphs hatch from eggs as early as
April, but continue to hatch from later deposited eggs through June. Nymphs develop for
about 5 mo and adults begin to appear in September. In some years there is a minor peak
of flight activity in the autumn, as early as August in the far south and as late as
December farther north if the weather remains warm. In most of the southern USA, the
spring activities occur in S. borellii about 3 wk later than in S. vicinus, but the autumnal
activities are concurrent. In south Florida, S. borellii has two generations during the
summer months, with a second peak in adult flight in July, following the first peak in
April. More S. borellii than S. vicinus overwinter as large nymphs. In contrast, all
developmental stages of S. abbreviatus occur throughout the year but with two peak
ovipositional periods, one in late spring and one in winter. Scapteriscus abbreviatus has
short, non-functional wings, cannot fly, and does not produce calling sounds. The peak
periods of damage caused by feeding of any species are when nymphs are abundant,
developing rapidly, and ingesting much food.
Turf damage mitigation is often the top priority of turfgrass managers and this is
usually achieved by applying pesticides. Insecticide classes used to manage mole cricket
populations include carbamates, organophosphates, phenyl pyrazoles and pyrethroids.
Insecticides commonly applied to control mole crickets in lawns and golf courses are
expensive and not always effective while in pastures there is no economically feasible
control (Walker 1985). Several risks are associated with insecticide use for mole cricket
control. For example, insecticides often have a short residual and treated areas are
subject to reinfestation. Insecticides are usually non-specific and therefore non-target
insects, including natural enemies, are killed by applications. Insecticide-treated mole
crickets may die on the soil surface, which attracts birds and other insectivores and risks
secondary mortality of these organisms. Improper applications may contaminate
groundwater by runoff or seepage (Frank and Parkman 1999). Finally, insecticide use on
golf courses and athletic fields requires that play be suspended for the legally required
no-entry time after treatment to minimize human exposure. Scapteriscus mole crickets
are therefore good targets for classical biological control (Frank 1990).
Other options for non-chemical control of mole crickets exist (e.g., cultural,
physical or mechanical controls), but are not readily applicable to turfgrass and pastures
of the southeastern USA. Examples include tillage at appropriate times of year to expose
eggs and small nymphs to desiccation and flooding (Denisenko 1986, Sithole 1986).
Reducing mowing height acts as a mechanical control by killing any mole crickets on the
There are several natural enemies of precinctive and exotic pest mole crickets in the
USA. Birds, mammals, amphibians, reptiles and arthropods attack mole crickets. They
include birds, raccoons and armadillos, toads, snakes, carabid beetles and earwigs.
Several fungal pathogens have been isolated from mole crickets in Florida, including
Aspergillus, Beauveria, Isaria, Metarhizium, and Sorosporella (Boucias 1985, Pendland
and Boucias 1987). Several arthropods are also used as biological control agents of
Scapteriscus mole crickets, including the phonotactic tachinid fly Ormia depleta
(Wiedemann), the neotropical digger wasp Larra bicolor F., Megacephala tiger beetles,
Pasimachus carabid beetles, and wolf spiders (Hudson et al. 1988, Parkman et al. 1996).
Of these, 0. depleta and L. bicolor have been released in Florida.
In 1988, a Brazilian strain of 0. depleta was released in Florida to parasitize exotic
mole crickets. The female fly locates Scapteriscus spp. by mating songs and deposits
larvae on or near the host. The fly's seasonality limits its spread so it has been more
successful in central and south Florida. Golf course superintendents have reported that
counties in Florida with 0. depleta populations had significantly less mole cricket
damage than did counties that lacked 0. depleta (Frank et al. 1996). Ormia depleta
seems to overwinter more successfully in central Florida than in northern Florida,
perhaps because of milder winters in central locations (Walker et al. 1996).
The neotropical digger wasp L. bicolor parasitizes large nymphs and adults of mole
crickets (Frank and Parkman 1999). The wasp attacks and stings mole crickets on the
soil surface, causing paralysis. The wasp deposits an egg on the mole cricket near the
pronotum, and the neonate larva develops as an external parasitoid. The parasitized mole
cricket resumes normal activities and dies after a few weeks. Scapteriscus mole crickets
are the only known host ofL. bicolor (Frank et al. 1995). However, this wasp also feeds
on wildflower nectar which can be used to maintain or increase populations in an area.
Insect Parasitic Nematodes
Insect parasitic nematodes have recently been investigated for use against
subterranean and soil inhabiting pests (Kaya and Gaugler 1993). Insect parasitic
nematodes in the genera Steinernema and Heterorhabditis are potent biological control
agents that generally infect their hosts by entering natural openings such as the mouth,
spiracles, and anus (Shapiro and Lewis 1999). Insect parasitic nematodes have been used
to control mole crickets and other insect pests such as lepidopteran larvae (Epsky and
Capinera 1994, Shapiro and Lewis 1999), banded cucumber beetle (Creighton and
Fassuliotis 1985), sweet potato weevil (Jansson et al. 1993), pecan weevil larvae
(Shipiro-Ilan 2001), western cherry fruit fly (Patterson-Stark and Lacey 1999), Japanese
beetle grubs (Klein and Georgis 1992, Schroeder et al. 1993), and various Homopterans
(English-Loeb et al. 1999). The nematodes in these genera are mutualistically associated
with bacteria (Xenorhabdus spp. for steinernematids and Photorhabdus spp. for
heterorhabditids). Infective juvenile nematodes enter the host through an opening in the
arthropod. Once in the hemocoel, they release their symbiotic bacteria, which kill the
host and provide nematodes with nutrients and defense against secondary invaders
(Poinar 1990). The nematodes complete two to three generations within the arthropod
host, and then infective juveniles are released to search out new hosts (Kaya and Gaugler
1993). Several steinermatid and heterorhabditid nematodes are in current use, or are
being considered for use, as commercial biopesticides against soil insects in many
agricultural and horticultural systems (Gaugler and Kaya 1990, Kaya 1990, Georgis and
Gaugler 1991, Kaya and Gaugler 1993). Disadvantages in using insect parasitic
nematodes include sensitivity to ultraviolet light, desiccation, and insect/pathogen
interactions (Kaya and Gaugler 1993, English-Loeb et al. 1999). Certain nematode
species are highly effective against a particular pest, whereas others may be ineffective or
moderately effective against the same pest (Shapiro-Ilan 2001). The effectiveness of
entomopathogenic nematodes depends on matching the target pest species with the most
The entomopathogenic nematode Steinernema scapterisci Nguyen and Smart was
collected in Uruguay in pitfall-trapped Scapteriscus mole crickets in the 1980s. The
nematode was cultured and then released in Florida pastures in 1985, established
populations and was spread from the release site by infected Scapteriscus mole crickets
(Hudson et al. 1988, Nguyen and Smart 1990a, Parkman and Frank 1992, Frank 2001).
The nematode successfully kills adults and large nymphs of S. borellii and S. vicinus and
to a lesser extent S. abbreviatus. Small to medium nymphs of S. borellii and S. vicinus
are less frequently infected (Hudson and Nguyen 1989a).
Steinernema scapterisci live in moist soil and can survive without a host for at least
10 wk (Nguyen and Smart 1990a). Third stage infective juveniles can migrate up and
down 10 cm in the soil and invade mole cricket bodies through the mouth or spiracles
(Nguyen and Smart 1991). Once inside the mole cricket, the nematodes release bacteria
that feed on the hemolymph killing the mole cricket through septicemia; the nematodes
then eat the bacteria and reproduce inside the mole cricket resulting in mole cricket
mortality within 2-3 d. The nematodes then exit the body and infect other mole crickets
in the soil. Mole crickets can fly up to 8 km before dying (Walker 1985), thus spreading
nematodes to new sites. The use of S. scapterisci as a biopesticide would allow treatment
to hot spots rather than doing a broadcast application of synthetic insecticides. Anecdotal
evidence indicates that since the original release of the nematodes (ca. 1985), overall
mole cricket populations in Florida have declined (J.H. Frank, personal communication).
Augmentative nematode releases are likely to further reduce mole cricket populations.
Over the past 20 years, researchers have become very interested in changes in
behavior displayed by parasitized animals and whether or not they represent parasite or
host adaptations (Poulin 1995). Changes in behavior displayed by parasitized organisms
vary from slight shifts in the time spent performing a given activity to appearance of
drastically new and strange behaviors (Poulin 1994, Benton and Pritchard 1990).
Oftentimes these parasite induced behavioral modifications are simply pathological side
effects of parasite infection (Poulin 1995, Vance 1996, Williams et al. 2001). Studies
with the thrips Frankliniella occidentalis (Pergande) and the entomopathogenic nematode
Thripinema nicklewoodi Siddiqi demonstrated behavioral change in the host insect. The
behavioral changes displayed were reduced feeding and reduced fecundity ofF.
occidentalis when infected with T. nicklewoodi (Arthurs and Heinz 2003). The results
from this study proved useful in the biological control of thrips because T nicklewoodi
reduce populations by parasitizing F. occidentalis, reducing direct feeding damage, and
reducing the spread of tomato spotted wilt virus.
Nematodes also modify their host's behavior to increase their own fitness.
Parasitism of the beach hopper Talorchestia quoyana Milne-Edwards by mermithid
nematodes results in a greater burrowing depth of the host. Adult mermithids live in
water or moist soil; however their beach hopper host prefers dry terrestrial microhabitats.
This behavior modification of the host allows the nematode to mate and lay eggs in more
humid environments deeper in the soil (Poulin and Latham 2002). Maeyama et al. (1994)
observed that the ant Colobopsis sp. infected with Mermis nematodes displayed a suicidal
behavior by jumping into water and dying. This behavior is advantageous to the
nematode because they require water to reproduce. In order to increase contact with a
mate, the nematodes must emerge from the ants in water.
More than 30 species of nematodes are associated with insects and other
invertebrates (Poinar 1979, 1990; Kaya and Stock 1997; Lacey et al. 2001; Koppenhofer
and Fuzy 2003). The nematode families Allantonematidae, Heterorhabditidae,
Mermithidae, Tetradonematidae, Sphaerulariidae, and Steinernematidae are the focus of
much research because of their potential as biological control agents of insects (Lacey et
al. 2001). For example, inoculative releases of Deladenus siricidicola Bedding in New
Zealand and Australia has been a successful classical biological control agent of the
woodwasp Sirex noctilio F. (Bedding 1993). The mermithid Romanomermis culicivorax
Ross and Smith has been used as a successful, inundative biological control agent for
mosquito larval suppression (Petersen 1985).
Steinernematid and heterorhabditid nematodes are second only to Bacillus
ith1n iigiJel'i, Berliner in commercial sales at $2-3 million dollars annually (Georgis
1997). These nematodes infect a number of insect species yet pose no threat to plants,
vertebrates, and many invertebrates (Akhurst 1990, Kaya and Gaugler 1993). They can
be mass produced, formulated, and easily applied as biopesticides; they also have been
exempt from registration in many countries, are compatible with many pesticides, and are
amenable to genetic selection (Georgis and Kaya 1988, Kaya and Gaugler 1993, Georgis
and Manweiler 1994).
Nematodes in the families Steinernematidae and Heterorhabditidae are especially
efficacious against insects in soil and cryptic habitats (Lacey et al. 2001). These
nematodes have been used inundatively in many high value crop systems (Georgis and
Manweiler 1994, Koppenhofer 2000). Successful uses of these nematodes against
economically important pests include the citrus root weevil, Diaprepes abbreviatus (L.),
in citrus, the black vine weevil, Otiorhynchus sulcatus (F.), in nurseries and cranberries,
the peach borer moth, Carposina niponensis Walsingham, in apples, and the black
cutworm, Agrotis ipsilon (Hufnagel), in turfgrass (Lacey et al. 2001).
Greater understanding of alternative controls, such as using insect parasitic
nematodes and how they fit into an integrated pest management program for mole
crickets in turfgrass, is needed. This research specifically assessed the effectiveness of
Steinernema scapterisci through a series of laboratory and field experiments. The
research included evaluating 1) the establishment of S. scapterisci in soil growing high
value golf course turfgrass, 2) effective drenching solutions in order to sample areas to
determine levels of nematode infected mole crickets, 3) compatibility of S. scapterisci
with insecticides, and 4) the effect of S. scapterisci infection on the reproductive and
tunneling behavior of pest mole crickets.
ESTABLISHMENT AND SPREAD OF Steinernema scapterisci ON FLORIDA GOLF
An integrated pest management program for pest mole crickets (Scapteriscus
abbreviatus, S. borellii, and S. vicinus) is being developed throughout the southeastern
United States. These insects damage turfgrass by tunneling and root feeding, that results
in large, irregular patches of dead turf throughout the year. Chemical control on golf
courses is still the primary means of preventive and curative control. Using resistant or
tolerant varieties or species of turfgrass, such as the bermudagrass hybrids 'TifSport' and
'Ormond', is possible but not common (Hudson 1986, Hanna and Hudson 1997, Braman
et al. 2000, Hanna et al. 2001, Reinert and Busey 2001). Cultural controls (i.e., adjusting
irrigation, fertilization, mowing heights, etc.) have not affected mole cricket populations
(Denisenko 1986, Frank et al. 1998, Frank and Parkman 1999. However, the introduction
and conservation of natural enemies that attack mole cricket adults is gaining momentum,
especially on pastures and Audubon International affiliated golf courses
The purpose of this study was to establish the efficacy of augmentative releases of
S. scapterisci against Scapteriscus spp. mole crickets on highly maintained golf courses
and athletic fields (Appendix B) as well as determining if subsequent applications of
nematodes would augment the nematode populations in the test area and increase the
percentage of mole crickets infected.
Materials and Methods
The establishment and spread of S. scapterisci was monitored on two golf courses
in Alachua Co., FL: Ironwood Golf Course and Gainesville Golf and Country Club.
Ironwood Golf Course (IGC) was an 18-hole city-owned public golf course built in 1964.
The roughs were bermudagrass (Cynodon dactylon Pers. x C. transvaalensis Burtt-Davy)
var. Tifway, mowed at 4.7 cm. Gainesville Golf and Country Club (GGCC) was an 18-
hole private course located 10.3 miles from Ironwood Golf Course. Gainesville Golf and
Country Club was built in 1962 and originally planted with bermudagrass var. Ormond
and the roughs were mowed at 3.2 cm. Ironwood Golf Course and GGCC had been
previously treated with S. scapterisci in the late-1980s and did not have any subsequent
treatments. Weather data, including minimum and maximum daily temperatures, relative
humidity, amount of monthly precipitation (from local weather stations located
approximately 1 mile from IGC and 9 miles from GGCC) and soil temperatures at 7.6 cm
below the soil surface, were documented on each collection date (Appendix A).
Mole Cricket Monitoring
Twenty hot spots of mole cricket activity were located in the roughs of ten fairways
on each golf course (two hot spots per hole). Linear pitfall traps (modified from
Lawrence 1982) were installed in the ground at least 80 m apart. Each golf course
fairway contained a trap located in one treated area and one untreated area.
Pitfall traps consisted of a 19 L plastic bucket placed in the ground and four PVC
(3 m long, 7.6 cm diameter) perpendicular arms with a 2.5 cm wide slit lengthwise along
the top. The arms were placed in the ground so the slits were flush with the soil surface
(Figure 2-1). The distal end of each arm was capped, so insects falling into an arm
eventually fell into a 3.8 L bucket containing approximately 3-5 cm of sand, located
within a 19 L bucket (Figure 2-2). Holes were drilled into the bottom of both buckets to
allow for water drainage. Traps on all sites were installed in September and October
Nematodes were released in the afternoon (approximately 1600) at Ironwood Golf
Course (31 October 2001) and in the morning (approximately 0700) at the Gainesville
Golf and Country Club (5 November 2001). Nematodes were applied in an aqueous
suspension of 1 billion nematodes/ 378.5 L of water applied using a boom sprayer
calibrated at 0.5 L/m2. The area treated was 20.1 x 20.1 m (0.04 ha) around one trap on
each fairway for both golf courses. All sites were irrigated with 0.6 cm of water before
and 0.6 cm after application. The pre-treatment dates for Gainesville Golf and Country
Club and Ironwood Golf Course were 11, 18, 25 October 2001.
Pitfall traps were used to monitor infection levels and mole cricket abundance
using methods similar to Parkman et al. (1993a, b). At each 24 h sampling period, the
buckets and arms were cleaned out and 3-5 cm of sand was placed into the inner bucket.
Traps were left for 24 h and adult and juvenile mole crickets with pronotal lengths > 4
mm (Hudson and Nguyen 1989a) were collected from traps and returned to the
laboratory. Crickets were tested for infection weekly for the initial 6 wk post-application
and one to two times a month thereafter for 1 yr on Gainesville Golf and Country Club
and 2 yr on Ironwood Golf Course. Turf quality (density, color) in the area immediately
surrounding the pitfall traps was assessed (1 = sparse or brown grass, 9 = dense or dark
green grass). Soil samples were taken from each golf course and soil texture was
analyzed using the sodium metaphosphate/hydrometer procedure. Traps were removed
from GGCC in October 2002 at the superintendent's request.
Percent of mole crickets infected with nematodes caught in the traps was
monitored and tested in the laboratory. Mole crickets were placed individually in 20 ml
plastic scintillation vials (Fisher Scientific) with 1-2 drops of deionized water, capped
and labeled. Mole crickets were examined at 7 and 10 d after death under a dissecting
scope (10X) for the presence of nematodes. Steinernema scapterisci were identified by
Dr. Khuong Nguyen, Entomology and Nematology Department, University of Florida.
Comparisons of infection rates between sites and years were subjected to analysis
of variance and Tukey's studentized range test or Student's t-test (SAS Institute 2001).
All comparisons were made at a 0.05 significance level. Non-transformed means plus or
minus one standard error of the monthly mean are presented.
Results and Discussion
Mole crickets infected with S. scapterisci were collected at both golf courses before
and after our augmentative applications. Infected mole crickets were only found in the
spring and fall of each year when the late instar and adults, the most susceptible life
stages to S. scapterisci infection, were present. Mean cumulative percentages ( SE) of
infection for mole cricket trap collections during the 2001-2003 field season from the
sites GGCC (22.1% + 10.5) and IGC (15.8% + 4.6) did not differ statistically (t = 2.00;
df= 2, 56; P > 0.0001). Monthly infection and baseline pretreatment infection levels for
IGC and GGCC are presented in Figures 2-3 and 2-4, respectively.
Pre-treatment infection rates at GGCC and IGC ranged from 10-15%. The
percentage of infected mole crickets in treated areas at GGCC exceeded pre-application
levels about 4-8 wk after application. The percentage of infected mole crickets in
untreated areas at both courses (>80 m from treated areas) equaled the percent infection
in treated areas after about 20 wk. Significantly fewer Scapteriscus spp. were collected
in year 2 than in year 1 at IGC (t = 2.47; df= 1, 37; P > 0.01). The S. scapterisci
population persisted throughout the entire study period, 1 yr for GGCC and 2 yr for IGC;
however at IGC the level of infection for year 2 was significantly less than year 1 (F =
6.63; df= 1, 37; P > 0.01). During this study fipronil and acephate were used on greens
of both courses; acephate was used in the roughs as a spot treatment on IGC. Data from
this study concur with Parkman et al. (1994) that more Scapteriscus adults were infected
with S. scapterisci than nymphs. Contrary to Parkman et al. (1994), overall infection of
S. borellii was lower than that of S. vicinus in this study. More S. vicinus were collected
in traps than S. borellii (Table 2-1).
Prior applications of S. scapterisci were made in 1988 and 1989 on Ironwood Golf
Course and Gainesville Golf and Country Club, respectively. Infection levels present in
mole crickets during the pre-treatment collections demonstrate that the nematodes can
survive in golf course soil where mole crickets are present and pesticides are used
regularly for 12 years. If the nematodes can persist for at least 12 years, then the
populations will probably last for many more years as effective biological control agents.
Steinernema scapterisci can survive for 10 wk in soil lacking mole crickets (Nguyen and
Smart 1990a), however if crickets are present the nematode recycles within the host in
soil environments and could survive for 12 years as demonstrated by our results. The
persistence of nematodes in the soil may reduce the populations of mole crickets leading
to an overall reduction of pesticide applications needed.
Establishment and persistence of S. scapterisci in pastures was evaluated by
Parkman et al. (1993a) for five years. Nematodes were applied as an aqueous solution
using a handheld watering can or by burying infected mole cricket cadavers at the test
sites. Crickets were collected using linear pitfall traps (Lawrence 1982) with electronic
callers located nearby to enhance local mole cricket populations. Based on their findings
S. scapterisci became established and persisted for five years at these pasture field sites.
Parkman et al. (1993b) also evaluated the efficacy of a single inoculative release of
S. scapterisci against mole crickets in pastures. Nematodes were applied in an aqueous
solution using a tractor-drawn chisel rig. Crickets were collected in pitfall traps placed at
50, 100, and 200 m from the center of the treated area. The nematode persisted at five of
the six sites and dispersed at least 150 m away from the initial treated area at three of the
sites (Parkman et al. 1993b). They found that inoculative releases of S. scapterisci were
an alternative to inundative releases for mole cricket suppression. Further tests (Parkman
et al. 1994) showed that S. scapterisci serves as an inoculative biological control agent
for Scapteriscus spp. mole crickets on golf courses and acted as a biopesticide for
relatively rapid suppression of pest populations (Parkman et al. 1993b). Establishment on
golf courses was not as successful as pastures; however there was a >27% pest population
reduction in areas where the nematode did persist (Parkman and Smart 1996).
Since its initial release in June 1985 in Alachua Co., Florida, S. scapterisci has
been non-commercially released and presumably established in at least 28 counties in
Florida. The nematode population established readily even after a single inoculative
release. The establishment of S. scapterisci has been demonstrated by strip and broadcast
spray applications. Mole crickets infected with S. scapterisci can fly several kilometers
before dying (Parkman and Frank 1992), thus potentially spreading nematodes to
uninfected sites. Therefore the use of S. scapterisci as a biopesticide would allow
treatment to hot spots rather than strict reliance on broadcast applications of synthetic
insecticides to provide long-term mole cricket suppression. However, the effect of
augmentative applications to hot spots of mole cricket activity has not been previously
From our results it is evident that a single augmentative application of S.
scapterisci is sufficient to enhance nematode populations throughout a local area (i.e., a
fairway). Augmentative applications of nematodes provided higher than baseline
infection levels for 17 mo post treatment at IGC and 8 mo post treatment at GGCC.
Infection levels fluctuated with the host population in our study. Mole cricket adults and
large nymphs are present in the spring and fall months of any given year therefore,
crickets infected with S. scapterisci were usually found in larger numbers during these
months. The reduction in mole cricket population levels in year 2 versus year 1 could be
attributed in part to the S. scapterisci applications suggesting that the augmentation of
nematode populations does help reduce the numbers of mole crickets present on highly
managed golf courses in north Florida. Levels of infection may also be influenced by
mole cricket age, activity, environmental conditions and predation by other arthropods
within a trap. Although a single application can establish nematode populations, an
augmentative application may be necessary to keep population levels high enough for
sufficient mole cricket control.
Mole crickets collected from the pitfall traps were subject to mortality from
organisms other than S. scapterisci. Organisms observed infecting mole crickets
included other species of insect parasitic nematodes (i.e., Heterorhabditis spp. and
Steinernema spp.), fungi (i.e., Beauvaria bassiana), predators (i.e., ground beetles,
spiders, earwigs, etc.), and other mole cricket parasitoids (Larra bicolor and Ormia
Previous research (Gaugler and Boush 1978, Molyneux 1985, Hudson and Nguyen
1989b, Smith 1999) has shown that there are several abiotic factors that contribute to the
success (or failure) of insect parasitic nematodes when used as a biopesticide. Abiotic
factors can significantly limit the nematodes' effectiveness to move, locate and enter a
host (Smith 1999). Some of these abiotic factors include ultraviolet light, desiccation,
soil moisture, soil texture and type, soil temperature, soil pH, and agrichemical
compatibility (see Chapter 4). In this study applications were done in the early morning
and late afternoon and watered in immediately after application to avoid nematode
damage from UV light and desiccation. Moisture is required for nematodes to move
through the soil (Hudson and Nguyen 1989b). Ames (1990) observed that infective
juveniles of S. scapterisci can survive up to 13 wk at wilting point (15 bars moisture
tension) and survive better in sandy loam than pure sand. In this study both courses had
sandy loam soil and were irrigated regularly. Several of the fairways and roughs on both
courses where crickets were collected were subject to flooding or extremely wet
conditions due to rain or excess irrigation. Molyneux and Bedding (1984) observed that
very saturated soils can inhibit nematode mobility and decrease their survival by creating
Steinernema scapterisci killed between 15-20% (on average) of mole crickets
collected in linear pitfall traps. However, because mole crickets may die as soon as 48 h
post-infection, this value may be an underestimate of the true percentage of kill.
Nematodes can kill generation after generation and this combined effect may be
something similar to compound interest (Frank et al. 2002). Steinernema scapterisci can
be an effective part of an integrated pest management system on managed turfgrass if
applied in the proper manner and in suitable locations where nematodes can survive.
Figure 2-1. Linear pitfall trap used to collect mole crickets.
Figure 2-2. 3.8 L catch bucket inside 19 L bucket of linear pitfall trap.
50 27 4
> 91 184
-c20 78 4
10 10 78 56
OCT01 NOV01 DEC 01 JAN 02 FEB02 MAR 02 APR02 MAY 02 AUG02 OCT02 MAR 03
Figure 2-3. Mean monthly ( SEM) percent infection of mole crickets collected in pitfall
traps at Ironwood Golf Course from areas treated with Steinernema
scapterisci. Only months with infection levels are presented. Untreated areas
received no S. scapterisci and were >80 m from treated areas. Dashed line
represents baseline pretreatment infection level. Data presented are for
Scapteriscus vicinus and Scapteriscus borellii combined. Total numbers of
mole crickets are presented above SEM bars.
OCT01 NOV 01 DEC 01 MAR 02 APR 02 MAY 02
Figure 2-4. Mean monthly ( SEM) percent infection of mole crickets collected in pitfall
traps at Gainesville Golf and Country Club from areas treated with
Steinernema scapterisci. Only months with infection levels < 0 are presented.
Untreated areas received no S. scapterisci and were >80 m from treated areas.
Dashed line represents baseline infection level. Data presented are for
Scapteriscus vicinus and Scapteriscus borellii combined. Total numbers of
mole crickets are presented above SEM bars.
Table 2-1. Percent infection (mean SEM) of Scapteriscus spp. mole crickets collected
from sites treated with Steinernema scapterisci.
Gainesville Golf and Country Ironwood Golf Course
Club (n=10 traps) 1 (n= 10 traps) 2
Nymphs 0(1) 0(15)
Adults 0(1) 3.3 2.6 (20)
Total 0 (2)* 1.6 + 1.3 (35)*
Nymphs 7.7 4.0 (70) 9.7 3.4 (208)*
Adults 13.9 + 4.5 (163) 33.2 7.0 (313)
Total 10.8 3.0 (233) 11.9 2.5 (521)
Pairs of means within columns followed by asterisks are significantly different, t-test (P >
0.05). Numbers in parentheses are the total mole crickets collected.
1 GGCC: F= 8.57; df= 2,111; P= 0.0003
2 IGC: F= 14.05; df= 2,155; P< 0.0001
SURVIVAL AND INFECTIVITY OF Steinernema scapterisci AFTER CONTACT
WITH SOIL DRENCH SOLUTIONS
Mole crickets are subterranean pests of turfgrass in Florida and much of the
southeastern United States (Walker and Nickle 1981, Walker 1985). Mole cricket
damage and cost of control in Florida in 1986 were estimated at $45 million with an
additional $33 million in Alabama, Georgia, and South Carolina combined (Frank and
Parkman 1999). Estimates of annual expenditure in 1996 were over $18 million for
insecticides in Florida turf, and over $12 million in control costs (Hudson et al. 1997).
Mole crickets damage turf by their tunneling in the soil, which exposes and dries out
roots and by direct root feeding. As a result, the turfgrass thins and bare patches appear.
The tunneling and mounds that mole crickets make also disrupt the playing surface on
golf courses, especially the roll of the golf ball on greens. Superintendents and golf
course members have little tolerance for damage (Frank and Parkman 1999). Insecticides
are usually targeted against the most destructive, nymphal stage. A more sustainable,
environmentally friendly management approach for mole cricket control is needed.
Several biological control agents have been investigated for control of Scapteriscus
spp. mole crickets in Florida (Hudson et al. 1988). One of these biological control agents
is an entomopathogenic nematode, Steinernema scapterisci. Steinernema scapterisci was
originally isolated from pitfall-trapped Scapteriscus vicinus in Uruguay in the 1980s
(Nguyen and Smart 1990b). The nematode was cultured and released in several Florida
counties in 1985, where it established a population, and was spread from the release site
by infected Scapteriscus mole crickets (Hudson et al. 1988, Parkman and Frank 1992).
The nematode kills the adult and late instar nymphs of Scapteriscus borellii and S.
vicinus, and to a lesser extent S. abbreviatus. Fewer small to medium-sized nymphs of S.
borellii and S. vicinus become infected (Nguyen 1988).
Several techniques have been used to sample mole crickets including counts of
dead nymphs and adults after insecticide applications (Short and Koehler 1979),
estimation of surface burrowing (Walker et al. 1982, Cobb and Mack 1989), pitfall
trapping (Lawrence 1982, Adjei et al. 2003), removal with a tractor mounted soil corer
(Williams and Shaw 1982), sound trapping (Walker 1985) and soil drenching (Short and
Koehler 1979, Walker 1979, Hudson 1989). However, results from each of these
techniques are often inconsistent (Short and Koehler 1979, Lawrence 1982, Hudson
1988). Comparisons of different methods have indicated that soil drenching with soap
solutions are the most practical and consistent at obtaining direct counts of mole crickets
(Short and Koehler 1979, Hudson 1988).
Soil drenching with a solution of 15 ml of lemon dishwashing detergent in 3.8 L of
water is inexpensive and commonly used by turfgrass managers to sample soil pests. Soil
drenches with soap solutions irritate mole crickets and force them out of the soil. Soap
flushes are often used for monitoring mole crickets to determine the size, age, and species
present, the relative population density over time, and for control timing. However, it
was suspected that soap flushes, when used to monitor mole crickets potentially infected
with S. scapterisci, might be lethal to the nematodes because we rarely found nematodes
in soap-flushed mole crickets (K.B. Nguyen and G.C. Smart, Entomology and
Nematology Dept., University of Florida, pers. comm.). Solutions such as pyrethroids,
ammonia, vinegar, Lysol, and other soap detergents have previously been tested as
potential soil drench solutions (Short and Koehler 1979).
This study was conducted to determine whether a standard soap detergent solution
affects S. scapterisci survival and infectivity in pest mole crickets. Potential alternatives
to the standard soap drench solution were also evaluated.
Materials and Methods
Nematodes and Mole Crickets
Steinernema scapterisci (Nematac S, Becker Underwood, Ames, IA) was stored
in a 70C cold room until use (<3 mo). Nematode viability was tested before each
application by dissolving a pinch (-10 mg) of Nematac S into water and observing
nematode shape and mobility under a light microscope. Healthy nematodes were opaque
in color and S-shaped with undulating movements. Dead or unhealthy nematodes were
translucent, straight, and lacked movement. The product was used if viability was >50%
and discarded if <50% viable.
Scapteriscus vicinus were collected from pitfall traps or sound traps in Alachua
Co., FL, and returned to the laboratory. Each mole cricket was placed in a 120-ml plastic
vial (Thornton Plastics Salt Lake City, UT) with sterilized sand and held for >14 d to
ensure health. Surviving mole crickets were used in this study. Mole crickets were
maintained at 230C with a photoperiod of 12:12 (L:D) and fed commercial cricket chow
(Purina, St. Louis, MO).
Nematode viability and infectivity were assessed after exposure to various
drenching materials. Steinernema scapterisci nematodes were extracted from Nematac
S using a modified Baermann technique (Nguyen and Smart 1990b). Steinernema
scapterisci nematodes were kept at a density of 10,000 infective juveniles in solutions of
water (control), lemon dishwashing detergent (Joy, Proctor and Gamble, Cincinnati,
OH), insecticidal soap (Safer Soap, Woodstream Corporation, Litiz, PA), and
permethrin (Spectracide Bug Stop, Spectrum Brands, St. Louis, MO) for test 1. The
mixtures were kept at room temperature in a 125-ml Erlenmeyer flask with 125-ml per
flask on a shaker at 65 rpm. There were five replicates for each treatment.
Concentrations were selected based on recommendations for flush extraction of mole
crickets in the field (Short and Koehler 1979) and label rates for mole cricket control.
After 24 h, 10-[l samples were taken from each treatment and placed on a microscope
slide. The numbers of living and dead nematodes were counted using a dissecting
microscope (10 x), three 10-[l counts were taken and averaged to determine percent
mortality for each replicate. Immobile nematodes were touched with a probe to determine
A second test was initiated to further test potential drench materials. Treatments
for test 2 included water (control), azadirachtin (Safer Brand BioNeem, Woodstream
Corporation, Litiz, PA), citrus oil (Green Sense, Garland, TX), garlic extract (Garlic
Barrier, Garlic Research Labs, Inc., Glendale, CA), lemon juice (ReaLemon, Mott's,
St. Louis, MO), permethrin (Spectracide Bug Stop, Spectrum Brands, St. Louis, MO)
and cyfluthrin (Bayer Advanced Lawn and Garden Complete Insect Killer, Bayer
Environmental Sciences, Montvale, NJ). Concentrations were selected based on label and
half label rates for mole cricket control. Methods from test 1 were repeated.
Nematode infectivity was assessed by filtering nematodes from above solutions and
adding 50 living infective juveniles (parasitic stage) to 120 ml plastic cups (Fisher
Scientific) containing 20 g sterilized sand, 4% deionized water, and one S. vicinus adult.
Dead mole crickets were dissected and the presence or absence of nematodes was
The above solutions were tested for their effectiveness at flushing mole crickets at
the University of Florida G.C. Horn Turfgrass Research Unit in Gainesville, FL, on 20
and 28 May 2003. Each treatment from tests 1 and 2 (3.8 L of each solution) was applied
to areas of bermudagrass (Cynodon dactylon Pers. x C. transvaalensis Burtt-Davy) var.
Tifway, that had mole cricket damage (75 x 75 cm2). The numbers of adult and first
instar mole crickets emerging from the soil within 3 min were counted. Five replicates
for each solution were completed. Any turfgrass phytotoxicity was noted 1 h post
application and 1 wk post application.
The effect of nematode infected crickets exposed to soap solutions was also tested.
Scapteriscus abbreviatus adults were obtained from a lab colony at the University of
Florida Entomology and Nematology Department, Gainesville, FL, and were inoculated
with about 10,000 nematodes by applying a predetermined amount (approximately 150
[l) of concentrated nematode solution onto a piece of filter paper (Fisher #P8, 5.5 cm)
inside a petri dish with one S. abbreviatus adult. The mole cricket was allowed to
incubate in the petri dish for 1, 5, 8, 12 or 24 h (five mole crickets per treatment).
Scapteriscus abbreviatus was used because S. vicinus adults were unavailable at the time
of the test. All infected mole crickets were then dipped into a 118 ml Solo souffle cup
(Gainesville Paper Co., Gainesville, FL) containing the soapy water or soapy water
followed by a deionized water rinse for 5 sec. Untreated controls were healthy,
uninfected mole crickets dipped in water. Mole crickets were placed into 20-dram plastic
scintillation vials (Fisher Scientific, Pittsburgh, PA) and observed every 24 h for 10 d.
On day 10, mole crickets were dissected and the presence of nematodes was noted.
Nematode mortality and field test data were subjected to an analysis of variance
(SAS Institute 2001). Treatments were compared to the control (water) using Dunnett's
means comparison method (a = 0.05). Nematode infectivity data were subjected to Chi-
square analysis (SAS Institute 2001). Treatments were compared to the control (water)
and the standard soap flush solution (4 ml lemon dish detergent/L water) using Dunnett's
means comparison method (alpha= 0.05). Nematode mortality data were transformed
using arcsine-square root transformation before statistical analysis; nontransformed data
are presented. Effects of nematode infected crickets exposed to soap solutions data were
subjected to ANOVA (SAS Institute 2001).
Results and Discussion
Permethrin at the label rate for mole cricket control caused significantly more
nematode mortality than resulted from water (Table 3-1). Nematodes exposed to all
treatments showed similar infectivity in mole crickets. Nematode mortality was similar
among all treatments in test 2 except citrus oil (Table 3-2). Nematodes surviving all
treatments, except azadirachtin and lemon juice, demonstrated a low percentage
infectivity of mole crickets, no significant treatment differences were.
In the field, insecticidal soap and the higher rate of permethrin flushed significantly
more mole crickets than water (Table 3-3). However, when all treatments were
compared to the standard lemon dish detergent, insecticidal soap and permethrin brought
a similar number of mole crickets to the surface (n = 55; F = 2.88; df= 10,54; P = 0.008).
None of the mixtures tested produced any noticeable phytotoxicity to the turf.
Soil drenches with a mixture of lemon dish detergent and water are commonly used
to monitor turfgrass insects such as mole crickets, chinch bugs (Blissus spp.), big-eyed
bugs (Geocoris spp.), and several species of caterpillars (Short and Koehler 1979,
Hudson 1989). Soil drenches are inexpensive and are not labor intensive when compared
with other methods of monitoring mole cricket populations. These other methods include
large linear pitfall traps (Lawrence 1982, Adjei et al. 2003), an emitter producing a
synthetic song of male mole crickets (Parkman and Frank 1993), and a soil-coring device
(Williams and Shaw 1982). Each method requires more than one person, and is labor
intensive or costly (Lawrence 1982, Williams and Shaw 1982).
Seventy percent of S. scapterisci died in the lemon dish detergent solution. Assays
for nematode infection of soap-flushed mole crickets, the method currently used by many
turfgrass managers, are likely to be inaccurate. Krishnayya and Grewal (2002) reported a
toxic effect of a common soap surfactant (Ajax) on S. feltiae Bovien nematodes. They
found a 24% mortality level of nematodes when incubated at 4, 24, 72, and 120 h
(Krishnayya and Grewal 2002). Kaya et al. (1995) reported an insecticidal soap (M-
Pede) adversely affected S. carpocapsae (Weiser) and Heterorhabditis bacteriophora
Poinar survival and infectivity. However, infectivity may not be affected if the
nematodes are combined with an insecticidal soap and applied immediately (Kaya et al.
1995). Nematodes cannot be stored in an insecticidal soap solution because without
aeration, nematode survival can be adversely affected (Kaya et al. 1995). The toxicity of
metal ions present in soap may be responsible for the high mortality in soap solutions
(Jaworska et al. 1994, Krishnayya and Grewal 2002).
Tests of exposure of nematode infected mole crickets to soap solutions show that
soap flush solutions do not greatly affect nematode infection at least 8 h post infection
(Table 3-4). The soap flush solutions may potentially kill nematodes in certain areas of
the body (i.e., mouth) and further testing should be done to determine this. Immediately
rinsing flushed mole crickets with clean water may potentially increase the accuracy of
determining nematode infection. The unavailability of S. vicinus at the time of
experimentation may have also led to inconsistent, low levels of infection. It is known
that S. scapterisci does not infect S. abbreviatus as successfully as S. vicinus or S. borellii
Although permethrin solutions killed some nematodes in our experiments, S.
scapterisci infectivity was not compromised and field flushes successfully extracted mole
crickets from the soil. Short and Koehler (1979) reported that pyrethrins were the most
effective material, flushing a mean of 19 mole crickets/m2. Hudson (1988) compared
three sampling techniques, soil flushing with lemon dish detergent or synergized
pyrethrins and a tractor mounted soil corer. None of the methods gave significantly
different results. Our results from the field test show drenching solutions of permethrin
are useful in determining whether mole crickets collected in the field are infected with S.
scapterisci nematodes. A soil drench containing permethrin may be the best monitoring
tool to flush mole crickets to determine the presence of S. scapterisci.
However, there are disadvantages to using pyrethroids as soil drenches for mole
crickets. Pyrethroid drenches at the half or full label rate may cause more mole cricket
mortality than using a soap solution. Subsurface mortality of mole crickets can be as
high as 65% when using pyrethroids or similar insecticides (Ulagaraji 1974, 1975;
Walker 1979; Hudson 1988). Applicator exposure to insecticides is increased when
using a pyrethroid soil drench.
Soil drenches are effective, non labor-intensive methods to sample soil insect
populations. Soap detergent solutions, although inexpensive, may not accurately indicate
mole crickets infected with S. scapterisci. Permethrin solutions are less cost effective,
but are effective at flushing mole crickets potentially infected with nematodes.
Table 3-1. Mean nematode mortality and percent of mole crickets infected with
Steinernema scapterisci after exposure for 24 h to various drenching
Mean % nematode
mortality ( SEM)1
Number of mole
crickets infected with
S. %q' iu/'/i% i (n=3)
Water n/a 2.0+ 1.4 2
Lemon Joy 15 ml/ 3.79 L 32.4 + 1.6 0
Insecticidal Soap 15 ml/ 3.79 L 40.0 + 5.5 1
Permethrin 18 ml/3.79 L 11.6+ 1.0 2
* Statistically significant values using Dunnett's method comparing treatments to water
1n 20; F= 34.58; df= 19, 3; P = <0.0001
2 More than 10 replicates are needed for statistical analysis.
Table 3-2. Mean nematode mortality and infectivity after exposure for 24 h to various
Mean % nematode
mortality ( SEM)1
Water n/a 3.6 +2.2
Citrus Oil 15 ml/ 3.79 L 10.6 + 3.2
Cyfluthrin 7.5 ml/ 3.79 L 2.2 + 2.2
Cyfluthrin 15 ml/ 3.79 L 0.6 + 0.6
Garlic Extract 111 ml/ 3.79 L 0
Lemon Juice 15 ml/ 3.79 L 1.8 + 1.8
Azadirachtin 60 ml/ 3.79 L 0.8 + 0.8
Permethrin 9 ml/3.79 L 2.0 + 1.3
Permethrin 18 ml/ 3.79 L 0
n = 45; F 3.80; df =44, 8;P =0.0025
2 More than 10 replicates are needed for statistical analysis.
Number of mole crickets
infected with S.
, ,q'/'//l i2 (n=3)
Table 3-3. Mean number of mole crickets emerging from bermudagrass using various
drenching solutions in May 2003.
Mean number of mole
crickets flushed ( SEM)
15 ml/3.79 L
7.5 ml/ 3.79 L
15 ml/ 3.79 L
111 ml/ 3.79 L
15 ml/3.79 L
60 ml/ 3.79 L
9 ml/ 3.79 L
18 ml/3.79 L
15 ml/3.79 L
5.4 1.3 *
Lemon joy 15 ml/3.79 L 4.6 2.1
* Means statistically significant values using Dunnett's method comparing treatments to
water n = 54; F= 2.88; df= 59, 10; P= 0.01
Table 3-4. Percent nematode infection from mole crickets exposed to treatment solutions
1, 5, 8, 12, or 24 h post infection.
Time Post Infection
Joy (15 ml/ 3.79 L)
Joy (15 ml/ 3.79 L) + H20 rinse
0 40 60*
40 40 100*
n = 75;F= 6.77; df= 14, 2; P < 0.0001
* Means within columns statistically significant values when compared to control.
1 Control = uninfected, healthy mole crickets immersed in water.
INTEGRATION OF INSECT PARASITIC NEMATODES WITH INSECTICIDES FOR
CONTROL OF PEST MOLE CRICKETS
Appreciation of high-quality turfgrass has recently led to rapid growth in the golf
course and landscape management industries (Zimmerman and Cranshaw 1990).
Associated with this growth have been an increased number of pesticide applications and
environmental concerns (Zimmerman and Cranshaw 1990). Restrictive legislation has
resulted in a greater need for alternative control methods. Insect parasitic nematodes
provide acceptable control of several soil and thatch infesting pests, such as white grubs
(Coleoptera: Scarabaeidae), billbugs (Coleoptera: Curculionidae), cutworms
(Lepidoptera: Noctuidae), and mole crickets (Orthoptera: Gryllotalpidae) (Zimmerman
and Cranshaw 1990).
Insect parasitic nematodes could be effective in integrated pest management
programs as long-term suppressive agents used in combination with quick knockdown
products like commercially available insecticides. Effects of selected pesticides on
entomopathogenic nematodes other than S. scapterisci have been reported in aqueous
solutions (Prakasa et al. 1975, Hara and Kaya 1983a, Das and Divakar 1987, Rovesti and
Deseo 1990, Zimmerman and Cranshaw 1990, Ishibashi and Takii 1993, Gordon et al.
1996, Koppenhofer and Kaya 1998) and in insect hosts following pesticide exposure
(Hara and Kaya 1982, 1983b). Several studies have demonstrated that pesticides can
decrease survival and infectivity of several entomopathogenic nematode species in the
families Steinernematidae and Heterorhabditidae (Hara and Kaya 1982, 1983a, 1983b;
Forschler et al. 1990; Zimmerman and Cranshaw 1990; Head et al. 2000). However,
combinations of insecticides and insect parasitic nematodes have a synergistic effect on
nematode infection rates against white grubs (Koppenh6fer and Kaya 1998; Koppenh6fer
et al. 2000a, 2000b; Koppenh6fer et al. 2002). It is important to determine what
interactions, if any, might occur when certain insecticides are used together with S.
Knowing which insecticides might affect nematode performance is important in the
development of integrated pest management programs. Our first objective was to assess
the compatibility of chemical and biological management of pest mole crickets. A
second objective was to determine if label rates or half-label rates of these insecticides
could increase nematode infection rates.
Materials and Methods
Steinernema scapterisci (Nematac S, Becker Underwood, Ames, IA) used in this
study was stored in a 70C cold room until use (< 3 mo). Nematode viability was tested
before each application by dissolving a pinch of Nematac S into water and observing
nematode shape and mobility under a light microscope. Healthy nematodes were opaque
in color and S-shaped with undulating movements. Dead or unhealthy nematodes were
translucent, straight, and lacked movement. The product was used if viability was >50%
and discarded if <50% viable.
Scapteriscus vicinus adults were collected from pitfall and sound traps in Alachua
County, FL, and returned to the laboratory. Each mole cricket was placed in a 120-ml
plastic vial (Thornton Plastics, Salt Lake City, UT) with sterilized sand and held for >14d
to ensure health; only mole crickets that appeared healthy were used in this study. Mole
crickets were maintained at 24-270C, with a photoperiod of 12:12 (L:D), and fed
commercial cricket chow (Purina, St. Louis, MO).
Five insecticides commonly used for mole cricket control were evaluated for their
effects on the entomopathogenic nematode S. scapterisci in the laboratory. They
included acephate (Orthene Turf, Tree and Ornamental Spray, Valent Professional
Products, Walnut Creek, CA), bifenthrin (Talstar GC Flowable, FMC Corporation,
Philadelphia, PA), imidacloprid (Nleiit' 75 WP, Bayer Environmental Science,
Montvale, NJ), fipronil (Chipco Choice granular, Bayer Environmental Science,
Montvale, NJ) and deltamethrin (DeltaGard T&O granular, Bayer Environmental
Science, Montvale, NJ). These commercially formulated insecticides were selected due
to their widespread use for mole cricket control in the southeastern United States.
However, only products or formulations that are typically mixed with water or watered in
were chosen for this test. Products were tested at half and full label rates.
Survival and Infectivity of S. scapterisci After Exposure to Pesticides
Nematode viability and infectivity were assessed after exposure to the pesticides.
To count nematodes, S. scapterisci were extracted from Nematac S using a modified
Baermann funnel technique (Nguyen and Smart 1990b). Approximately 40-50 g
Nematac S was placed on two layers of unscented, non-lotion, white facial tissue
(Puffs, Procter & Gamble, Cincinnati, OH). The tissue was then placed on top of a 1-
mm screen filter in a square plastic container (13 x 13 cm2) and moistened with deionized
water. Approximately 100-110 ml of deionized water was added to the plastic container.
The setup was then placed on a laboratory counter at 24-270C for 5-8 h, during which
time the living nematodes moved through the tissue and filter into the water below. The
nematodes were then counted by taking an average of three, 10-rl samples.
Steinernema scapterisci were kept at a density of 10,000 infective juveniles per 125
ml in aqueous solutions of water (control), half or full label rates of acephate (1 or 2 kg
AI/ha), bifenthrin (112 or 224 g AI/ha), or imidacloprid (275 or 451 g AI/ha). The
mixtures were kept at room temperature (24-27 C) in a 125-ml Erlenmeyer flask on a
rotator at 65 rpm. There were five replicates for each treatment. After 24 h, 10-rl
samples were taken from each flask and placed on a microscope slide. The numbers of
living and dead nematodes were counted using a dissecting microscope (10 x). Immobile
nematodes were touched with a minute probe to determine survival. Three 10-rl counts
were averaged to determine percent mortality for each replicate. Nematode infectivity
was assessed by removing nematodes from above solutions and adding 50 living infective
juveniles to 120 ml plastic cups (Fisher Scientific, Pittsburgh, PA) containing 50 g of
sterilized sand moistened with deionized water and one S. vicinus adult. After death,
mole crickets were dissected and the presence or absence of nematodes was recorded.
Nematode Infectivity After Exposure to Pesticide Treated Mole Crickets
Percent infectivity of nematodes when exposed to mole crickets treated with
insecticides was also assessed. Mole crickets were placed in 120 ml plastic cups
containing 50 g of sterilized sand that was treated with label or half label rates of
acephate, bifenthrin, imidacloprid, fipronil (140 or 280 g AI/ha), or deltamethrin (73 or
146 g AI/ha). Pesticides were applied to the top of the sand and mixed into the sand by
capping the cup and shaking by hand before adding the mole cricket. The mole crickets
were allowed to move through the insecticide treated sand for 24 h. Mole crickets were
then removed and placed into new cups containing 50 g of sterilized sand moistened with
deionized water and nematodes. To ensure mole cricket infection the number of
nematodes used was increased to 500 infective juvenile S. scapterisci. Mole crickets
were fed cricket chow twice a week. Dead mole crickets were removed from the sand
cups and placed individually in 20 ml plastic scintillation vials. Mole crickets were
examined 5-7 d after death under a dissecting scope (10 X) for the presence or absence of
nematodes. The test concluded at 47 d, by which time all of the mole crickets had died.
There were five replicates (mole crickets) for each treatment.
Nematode mortality data were subjected to an analysis of variance (SAS Institute
2001). Treatment means were compared by Tukey-Kramer Honestly Significant
Difference means separation test (P= 0.05). Nematode infectivity data are presented as
number of crickets infected with S. scapterisci out of five total crickets tested. Nematode
mortality data were transformed using arcsine square root transformation before
statistical analysis; nontransformed data are presented.
Results and Discussion
None of the solutions tested reduced S. scapterisci survival (Table 1). Survival
ranged from 95.6% (bifenthrin, label rate) to 100% (imidacloprid, half label rate). The
average number of days until mole cricket death was not significantly different from the
control in any treatment except imidacloprid (Table 1; F= 1.83; df=10, 54; P<0.001).
None of the infectivity levels were significantly different from the control. Between 2
and 4 of the mole crickets tested became infected with the nematodes from the solutions
tested. Mole crickets treated with imidacloprid survived significantly longer than those
in the other treatments, but it was not significantly different from the control (Table 2).
The percent nematode infection of mole crickets previously exposed to solutions of
insecticides ranged from 40-100% (Table 2; F=14.78; df=10, 54; P<0.001). Infectivity
did not significantly differ among any of the treatments tested.
These results suggest that the pesticides tested can be successfully used with S.
scapterisci applications. Organophosphate insecticides can kill S. carpocapsae (Weiser)
infective juveniles (Dutky 1974), or as with carbamates, paralyze them (Hara and Kaya
1982, 1983a). The organophosphate used in our study, acephate, did not have a
significant effect on survival and infectivity of S. scapterisci adults. Our results indicate
that the pesticides tested in this study are compatible with S. scapterisci infective
Previous laboratory studies with other steinernematid nematodes (excluding S.
scapterisci) have demonstrated compatibility with pesticides (Ishibashi et al. 1987,
Zimmerman and Cranshaw 1990, Ishibashi and Takii 1993, Head et al. 2000). Results
from field collected mole crickets have demonstrated that S. scapterisci applied to
intensively managed bermudagrass (Cynodon spp.) in Gainesville, FL, in October 1989
persisted and were recovered in mole crickets collected in October 2001 (Frank et al.
2002). This evidence along with the results presented here support the compatibility of
using S. scapterisci with current mole cricket management strategies. Frank and
Parkman (1999) stated that the optimal use of S. scapterisci would be in the roughs of
golf courses and areas where tolerance for damage is higher and turf is less intensively
maintained. Our results show that an insecticide treated mole cricket has the potential of
being infected by nematodes and nematode reproduction does occur within the treated
Although our study did not directly test tank-mixing effects, we suggest the
potential for tank mixing exists using the wettable or liquid/flowable insecticides tested in
this study and Nematac S. However, there are several possible limitations to tank-
mixing with S. scapterisci. First, chemicals for mole cricket control are usually applied
in early summer for control of young nymphs while S. scapterisci is applied in the spring
or fall for adult control. Irrigation is recommended before and after Nematac S is
applied, thus tank mixing is only possible with pesticides that require watering in.
Because nematodes are sensitive to extreme heat and ultraviolet light (Gaugler and Boush
1978), they should be applied at dawn or dusk, which may conflict with applicator work
hours. The pesticides tested may provide a quick knockdown for late instar and adult
mole crickets, and S. scapterisci may provide a more sustainable, long-term control of
An insecticide that could modify an insect's behavior to stop or prevent feeding or
tunneling damage, and also inhibit the insect's ability to defend against parasitism or
infection, would be a valuable component of integrated pest management. For example,
imidacloprid is synergistic with S. glaseri (Steiner) or Heterorhabditis bacteriophora
Poinar against white grubs (Koppenh6fer et al. 2000a, 2000b). Imidacloprid disrupts a
grub's normal nerve function, which drastically reduces its activity, affects grooming and
evasive behaviors, and facilitates nematode attachment onto the cuticle (Koppenh6fer et
al. 2000a, 2000b). In our study, mole crickets treated with imidacloprid survived longer
than those treated with the other insecticides, but still died from nematode infection.
Steinernema scapterisci are ambush nematodes, unlike the cruiser nematodes tested by
Koppenh6fer et al. (2000a, b). Pesticides which increase mole cricket activity, rather
than slow it down, may result in increased contact with ambush nematodes. However, if
grooming is also increased, then nematodes may not be able to attach to the host. The
half-label rates of acephate and deltamethrin had greater infectivity (Table 2).
A more integrated and sustainable management plan for mole crickets is possible
using biological, cultural and chemical control. Natural enemies have become
established in Florida and actively target adult mole crickets and large nymphs. Insect
parasitic nematodes (e.g., S. scapterisci) can be applied as biopesticides for large nymph
and adult mole cricket control in the spring and fall. Cultural controls such as using non-
attractive lights during adult flight periods, monitoring life stages using pitfall traps or
soap flushes in order to time control methods (Hudson 1985), and planting nectar sources
for parasitic insects (Frank et al. 1995) should also minimize infestations while selective
use of preventive and curative insecticides can quickly control young nymphs during the
Table 4-1. Percent survival, infectivity, and days until death of S. scapterisci incubated in solutions of insecticides for 24 h.
Common Name Trade name Rate Nematode survival Days until mole cricket Number of mole
(%) SEM (n=5) death SEM (n=5) crickets infected (n= 5)
Acephate Orthene TT&O Spray 1 kg AI/ha 96.3 + 1.6a 1.4 + 0.2b 4
2 kg AI/ha 97.5 1.2a 1.4 0.2b 3
Bifenthrin Talstar GC Flowable 112 g AI/ha 95.9 1.7a 2.8 1.0Ob 3
224 g AI/ha 95.6 1.8a 1.6 0.2b 3
Imidacloprid Merit 75 WP 275 g AI/ha 100.0 + Oa 23.2 8.9a 2
451 g AI/ha 98.2 1.8a 22.2 4.0a 2
Control (water) n/a n/a 99.8 0.2a 17.0 3.9ab 4
Mean standard error of the mean (SEM), means within columns followed by different letters are significantly different at a = 0.05
using Tukey's Honestly Significant Difference means separation test.
Table 4-2. Average days until death and percent infectivity by S. scapterisci nematodes to mole crickets exposed to insecticides.
Days until mole cricket
death SEM (n=5)
Number of mole crickets
infected (n= 5)
Orthene TT&O Spray
Talstar GC Flowable
DeltaGard T&O G
Chipco Choice G
Merit 75 WP
1 kg AI/ha
2 kg AI/ha
112 g AI/ha
224 g AI/ha
73 g AI/ha
146 g AI/ha
140 g AI/ha
280 g AI/ha
275 g AI/ha
451 g AI/ha
1.0 + 0b
1.0 + 0b
1.0 + 0b
1.0 + 0b
1.0 + 0b
1.0 + 0b
1.0 + 0b
EFFECT OF Steinernema scapterisci NGUYEN AND SMART EXPOSURE ON MOLE
CRICKET TUNNELING, OVIPOSITION, AND AVOIDANCE BEHAVIOR
Avoidance of nematodes has been observed in soil inhabiting insects (Thurston
1994, Wang et al. 2002, Zhou et al. 2002). Laboratory evaluation of four
entomopathogenic nematodes for control of subterranean termites revealed that
Heterorhabditis indica Poinar repelled termites at high concentrations (Wang et al.
2002), but length of repellency varied with nematode concentration. Ants are also
repelled by products produced by the bacteria within nematodes (Zhou et al. 2002). The
symbiotic bacteria Xenorhabdus nematophila and Photorhabdus luminescens of
Steinernema carpocapsae and Heterorhabditis bacteriophora respectively produce "ant-
deterrent factors (ADF)". These ADFs are compounds that deter scavengers and protect
the nematodes from being eaten during reproduction within host cadavers (Zhou et al.
2002). Nematodes have the ability to detect and avoid toxic compounds in their
environment (Hilliard et al. 2004). The nematode Caenorhabditis elegans has the ability
to avoid toxic compounds such as quinine (Hilliard et al. 2004).
Soil insects have been observed to sense and avoid areas treated with insecticides,
pathogens, or nematodes (Villani et al. 1994, Milner and Staples 1996, Villani et al. 1999,
Thompson 2004). Soil insects are often highly susceptible to pathogenic organisms in the
laboratory, however are rarely infected in the field, indicating a possible behavioral
component of microbial defensive tactics (Villani et al. 1999). Metarhizium anisopliae
(Metsch.) incorporated into soil is repellent to Japanese beetle grubs (Villani et al. 1994).
Termites also detect and avoid Metarhizium conidia in soil (Milner and Staples 1996).
Mole crickets are repelled by soil treated with Beauveria bassiana (Brandenburg 2002,
Villani et al. 2002). Thompson (2004) observed mole crickets avoiding soil treated with
the Beauvaria bassiana strain 10-22 and Talstar in the greenhouse.
This study determined how mole cricket tunneling changes over time after
exposure to varying numbers of S. scapterisci, as well as to determine whether healthy
mole crickets avoid nematode treated soil and how the oviposition behavior of infected
female mole crickets is affected. We wanted to ascertain if mole crickets can sense and
avoid nematodes over long distances (ca. 15 cm) and, when given a choice between
nematodes and pesticides, would the nematode treated areas be preferred over pesticide
treated areas. This information will help in developing a successful IPM program using
S. scapterisci and pesticides, as well as determine ways in which application of S.
scapterisci could be improved or modified to increase infection rates and reduce pesticide
Materials and Methods
Steinernema scapterisci (Nematac S, Becker Underwood, Ames, IA) used in this
study was stored in a 70C cold room until use (< 3 mo). The viability of the nematodes
was tested before each application by dissolving a pinch of Nematac S into water and
observing nematode shape and mobility under a light microscope. Healthy nematodes
are opaque in color and S-shaped with undulating movements. Dead or unhealthy
nematodes are translucent, straight, and lack movement. The product was used if
viability was >50% and discarded if <50% viable.
Tawny (Scapteriscus vicinus) and southern (Scapteriscus borellii) mole crickets
were collected from pitfall traps or sound traps in Alachua Co., FL, during the fall and
spring of 2003 and 2004 and returned to the laboratory. Each mole cricket was placed in
a 120-ml plastic vial (Thorton Plastics Salt Lake City, UT) with sterilized sand and held
for >14 d to ensure health. Mole crickets were maintained at 230C with a photoperiod of
12:12 (L: D) and fed commercial cricket chow (Purina). Scapteriscus abbreviatus were
obtained from a laboratory colony at the University of Florida Entomology and
Nematology Department and maintained under the same conditions described above.
Nematode Infection and Nematode Treated Areas Effect on Mole Cricket Tunneling
Two dimensional tunneling behavior assays were conducted on Scapteriscus
vicinus adults that were either healthy or infected with Steinernema scapterisci. Plexiglas
containers (30.5 cm wide x 30.5 cm high x 2.5 cm deep) were filled with autoclaved
sand, moistened with deionized water, positioned vertically, kept in a dark area to
simulate a subterranean environment, and observed under a red light bulb (40W).
Ryegrass (Lolium multiflorum) was grown on top of the containers as a food source for S.
vicinus. After the grass established a root system approximately 10-15 cm in length, one
adult mole cricket previously exposed to nematodes (0, 500, or 10,000 infective
juveniles) was placed in a randomly selected area at the top of the container. Five males
and five females were tested for each treatment level. A small strip of Plexiglas was
placed in the top opening of the arena to prevent mole cricket escape. Tunnel dimensions
in the sand were measured at 1, 4, 8, 24, 48, 72, and 96 h then every 48 h after that for 10
d or until mole cricket death, whichever occurred first. Tunnel patterns were traced on
acephate paper, and then lengths were measured with a cloth measuring tape. Time that
tunnel construction slowed down or ceased was recorded. Daily tunnel distances were
determined by subtracting total tunnel distance from the previous day's tunnel distance.
Mole crickets were then removed from the arenas and assayed for nematode infection.
There were 10 replicates (crickets) for each treatment.
Additional tests were completed to determine whether healthy mole crickets could
sense and/or avoid nematode-treated soil. Autoclaved builder's sand was colored with
blue-powdered chalk (American Tool Companies, Inc., Wilmington, OH) and placed on
one half of a 30.5 cm wide x 30.5 cm high x 2.5 cm deep Plexiglas arena with the other
half containing sand colored with orange powder (American Tool Companies, Inc.,
Wilmington, OH). Ryegrass was grown on top of the containers to provide food for the
mole crickets. The blue colored sand was inoculated with a label rate (approximately
25,000 nematodes/cm2) of S. scapterisci by injecting approximately 100 ml of nematodes
in solution to one corner of the container using a graduated cylinder. To determine if
there were any deterrent effects of the chalk used to color the sand, control arenas were
setup similar to the treated arenas. Healthy mole crickets were placed in the control arena
with colored sand, however both sides of the arenas lacked nematodes. The controls
were treated exactly as the treatment arenas.
The containers were kept in a dark area to simulate subterranean conditions and
observed under red light (40 W). One mole cricket was placed on the untreated side of
the Plexiglas arena. Half of the replicates contained orange sand treated with nematodes
with untreated blue sand and the other half contained blue sand treated with nematodes
and untreated orange sand. Tunnels and movement of nematode infected sand was
compared to movement of untreated sand by looking at the tunnel patterns and movement
of the treated sand. Mole cricket behavior was observed at 1, 4, 8, 24, 48, 72, and 96 h
then every 48 h after that for 10 d or until mole cricket death, whichever occurred first.
Data were summarized into 48 h increments. The length of the tunnel system was
determined as previously described. After 10 d mole crickets were removed from the
arenas and assayed for nematode infection. There were ten replicates (mole crickets).
Mole crickets used in this study were dissected after 10 d (or after death, whichever
Oviposition Behavior of Mole Crickets Exposed to S. scapterisci
The oviposition behavior including number of eggs, clutch size, depth and width of
egg chambers, and time until oviposition was also observed in the previous tests. After
10 d the arenas were dismantled and egg clutches were removed. An indentation was
made in 55 mm Petri dishes filled with moistened sterilized sand by pressing a gloved
finger into the moistened sand. Eggs were carefully removed using feather-weight
forceps and placed into the depression. Petri dishes were covered and wrapped with
parafilm (Fisher Scientific, Pittsburgh, PA) to keep humidity levels high. Eggs were
monitored every 48 h until egg hatch.
Response of mole crickets to potentially lethal compounds was tested in a dual
choice observation chamber intended to simulate below ground tunnel conditions. Y-
tube arenas were constructed to evaluate the response of Scapteriscus borellii, S. vicinus,
and S. abbreviatus to Steinernema scapterisci or untreated sand, and the choice between
nematodes or pesticides. Arenas were constructed of 1.27 cm diameter plastic tubing
(Fisher Scientific, Pittsburgh, PA), the basal section was 15 cm long, and each arm was
10 cm long. The tubing was connected to form a Y using a 1.27 cm plastic y-connector
(Fisher Scientific, Pittsburgh, PA).
Autoclaved builder's sand was loosely packed in either arm of the Y-tube.
Comparisons consisted of 500 against 0 nematodes. Nematodes were added to the sand
using a pipet. Each arm was capped with a 20 ml plastic scintillation vial (Fisher
Scientific, Pittsburgh, PA). The 15 cm entry arm was left void of sand to facilitate mole
cricket movement. Ten replicates of S. borellii and S. vicinus were completed for each
level of nematodes; each replicate was completed using a different cricket. Experiments
were carried out at 23 C in dark conditions using red light (40W) to observe the mole
crickets. One adult S. borellii or S. vicinus was placed into the basal section of the Y-
tube. The cricket was observed as it moved through the tubing at the base and then chose
between the arms containing treatments. Choice was determined when a cricket traveled
completely through one arm and entered the scintillation vial at the end. Y-tubes were
cleaned with a 1% bleach solution between runs and re-used for nematode studies only.
Response to S. scapterisci or Pesticides
Five insecticides commonly used for pest mole cricket control were evaluated in
the laboratory against nematodes for their attractive or repellent characteristics to mole
crickets. The pesticides tested were acephate (0.91 kg AI/ha) (Orthene Turf, Tree and
Ornamental Spray, Valent Professional Products, Walnut Creek, CA), bifenthrin (224 g
AI/ha) (Talstar GC Flowable, FMC Corporation, Philadelphia, PA), imidacloprid (451 g
AI/ha) (Merit 75 WP, Bayer Environmental Science, Montvale, NJ), fipronil (280 g
AI/ha) (Chipco Choice, Bayer Environmental Science, Montvale, NJ) and deltamethrin
(146 g AI/ha) (DeltaGard T&O, Bayer Environmental Science, Montvale, NJ).
Autoclaved builder's sand was loosely packed in one arm of the Y-tube and 10,000
nematodes were added using a pipet. The second arm contained autoclaved builder's
sand mixed with 1 ml of the label rate of the above pesticides. Each arm was capped
with a 20 ml plastic scintillation vial (Fisher Scientific). The 15 cm basal entry arm was
empty. Seven replicates were completed for each insecticide; each replicate was
conducted using a naive cricket. Experiments were conducted using the same methods
described in the previous Y-tube tests. Y-tube arenas used in pesticide studies were
discarded after use to prevent contamination.
Tunneling and oviposition data were subjected to an ANOVA (SAS Institute 2001)
and means were separated using the Tukey-Kramer Honestly Significant Difference
means separation test. Within each Y-tube test, the number of crickets responding to
each choice was analyzed by a chi-square test against the null hypothesis of a 1:1 ratio
(Steel and Torrie 1981).
Effect of Nematode Infection and Nematode Treated Areas on Mole Cricket
Tunneling rate of mole crickets treated with 0, 500, 10,000 nematodes did not
significantly differ over time among the treatments (Figure 5-1). Total distance tunneled
over the entire 10 d period (29-44 cm) was not statistically significant among the three
treatments (F= 0.87; df= 2, 35; P= 0.43). Mole crickets treated with 500 or 10,000 S.
scapterisci tended to tunnel less (lower average daily distance) when compared to healthy
mole crickets (Figure 5-2). There were no significant differences between male and
female mole cricket tunneling when exposed to different levels of nematodes (F=1.073;
df= 5, 23; P=0.408). During the 10 d test, the eight mole crickets treated with 0, 500, or
10,000 nematodes had 0, 1, and 3 crickets respectively infected with nematodes. Tunnel
distances began to decrease after 6 d in crickets treated with 500 or 10,000 nematodes.
Mole crickets did not appear to differentiate between untreated and nematode-
treated sand (F= 1.93; df=l1, 79; P= 0.1684). Tunnel length did not differ in either side of
the arena at anytime during the test (Figure 5-3). There were no significant effects on
tunneling or viability of crickets in arenas with sand lacking nematodes and tinted with
orange or blue colored chalk (F=2.94; df=l, 49; P=0.5899). Several mole crickets did
not venture far from the top 10 cm, and these crickets were the first to die. All mole
crickets were infected with S. scapterisci.
Oviposition Behavior of Mole Crickets Exposed to S. scapterisci
Mole crickets infected with 500 or 10,000 nematodes were able to lay eggs, to
about the same soil depth, in the same chamber dimensions, and in a similar quantity to
uninfected females (Table 5-1). These behaviors also did not differ in treated vs.
untreated sand (500 or 10,000 nematodes) (Table 5-2). Healthy mole crickets and those
treated with 10,000 nematodes laid eggs between 1-6 d. Crickets treated with 500
nematodes laid eggs between 1-10 d. One female cricket treated with 500 nematodes
either buried or consumed her clutch of eggs during the study period. None of the eggs
survived due to mold growth.
None of the three mole cricket species tested demonstrated a significant choice
between arms treated with 500 or 10,000 S. scapterisci (S. borellii, S vicinus, or S.
abbreviatus; y2 = 2.4, 2.1, and 1.6 respectively for 500 nematodes; S. abbreviatus and S.
vicinus; 2 = 1.6, and 2.4, respectively for 10,000 nematodes). Most mole crickets tested
chose the arm that contained S. scapterisci when given a choice between S. scapterisci or
insecticides (Table 5-4). Crickets, when given a choice between S. scapterisci and
fipronil chose the arm containing fipronil. Fipronil granules did not readily dissolve in
water and the solution tended to stay at the very distal end of the arm reducing contact
with the mole cricket.
Although mole crickets have been observed avoiding entomopathogens such as
Beauveria bassiana and Metarhizium anisopliae (Villani et al. 1999, Brandenburg 2002,
Villani et al. 2002, Thompson 2004), they do not appear to avoid the insect parasitic
nematode S. scapterisci. In this study we sought to determine if infection of Scapteriscus
spp. with S. scapterisci caused any modification of tunneling behavior. Although the
results were not statistically significant, the crickets infected with 10,000 nematodes
tended to tunnel less than crickets treated with 500 nematodes and healthy crickets. The
shape and length of the tunnels formed by S. borellii concur with Brandenburg et al.
(2002). Both healthy and nematode-infected crickets typically formed an inverted y-
shaped tunnel with branching occurring lower than the surface of the arenas. Our results
show that crickets infected for >6 d may not tunnel as much or as deep as uninfected
mole crickets. This shallow tunneling behavior may make the mole crickets more
vulnerable to insecticides, management practices such as aeration, or increase
vulnerability to predators such as birds and armadillos.
Because insect parasitic nematodes are slower-acting than chemical pesticides the
mole crickets may continue to oviposit during the period of infection before death. Our
results indicate no significant differences in the ovipositional behavior of female crickets.
Females infected with nematodes may not have the energy or resources available for egg
laying because these resources are required for immune system defense and the female
may die before completing oviposition. Research on Beauveria bassiana has involved
the effects of infection on oviposition behavior of Lygus hesperus (Hemiptera: Miridae)
an important crop pest in the western United States (Noma and Strickler 2000). Lygus
hesperus oviposition is significantly reduced after inoculation with B. bassiana in the
laboratory. Nematodes in the genus Steinernema have also resulted in reduced overall
host fecundity (Belair and Boivin 1995, Kim et al. 2004).
Scapteriscus borellii adults laid a similar number of eggs in nematode treated and
untreated sand in the Plexiglas arenas, indicating a lack of repellency by the nematodes.
Thus, a female ovipositing in soil treated with Nematac S may then become infected,
although her offspring are not likely to be immediately affected. We were unable to
assess egg viability in these tests due to excessive mold development (none of the eggs
Mole crickets have been observed avoiding insecticides (Brandenburg 2002;
Thompson 2004). If mole crickets can sense and avoid insecticides applied to tees,
greens, and fairways this may potentially force the cricket into the roughs where
nematode applications could be made. In our tests, when given a choice, mole crickets
chose sand treated with S. scapterisci over sand treated with the insecticides tested. The
sensory system of mole crickets is not well understood (Villani et al. 1999; Brandenburg
2002; Villani et al. 2002; Thompson 2004). Initial scanning electron microscope
photographs (Appendix D) indicate many hairs covering the antennae, tarsi, and palps.
These hairs may be due to the insect's subterranean habitat and not for sensory detection.
Sensory detection in mole crickets should be studied further. Knowledge of mole cricket
sensory detection would be useful in development of a mole cricket IPM program.
The fact that Scapteriscus borellii oviposited in a laboratory arena is also new
information. The common rearing method for S. abbreviatus in the University of Florida
colony in Gainesville, FL is in cylindrical 120-ml plastic vials with autoclaved sand.
This method was unsuccessful for the author when rearing S. borellii or S. vicinus;
however oviposition was observed in females placed in the Plexiglas sandwich arenas
used for this study. The larger arenas may provide more room for the crickets to move
around; also females could tunnel down 30.5 cm versus only several centimeters in the
plastic vials. The moisture level also remained relatively high in the Plexiglas arenas.
High humidity is necessary for successful mole cricket oviposition (Hertl et al. 2001).
o 0 nematodes
* 500 nematodes
E 10,000 nematodes
2 4 6 8 10
Figure 5-1. Distance (cm) tunneled ( SEM) through sand in Plexiglas arenas every 2 d
by mole crickets exposed to varying amounts of nematodes. ANOVA for
2,4,6,8, and 10 d are (F=0.45; df=2,34; P=0.64); (F=1.45; df=2,32; P=0.25);
(F=0.32; df=2,31; P=0.73); (F=0.61; df=2,31; P=0.55); (F=1.49; df=2,29;
0 500 10000
Number of Nematodes
Figure 5-2. Comparison of total tunnel distances ( SEM) by male and female
Scapteriscus spp. mole crickets after exposure to S. scapterisci.
1 5 15 24
Figure 5-3. Distance tunneled ( SEM) by mole crickets through sand treated with
nematodes and untreated sand in Plexiglas arenas over 48 h.
Table 5-1. Oviposition of Scapteriscus mole crickets directly infected with different
numbers of S. scapterisci.
# Mole Width of egg Depth of egg
Treatment crickets that Number of eggs
(# nematodes) laid eggs (+ SEM) chamber (cm) chamber (cm)
(n=8) SEM) SEM)
0 5 17.25 + 5.36 2.81 + 1.07 12.93 + 4.14
500 6 19.25 5.01 2.74 0.91 11.34 2.71
10,000 4 12.63 + 4.85 1.70 + 0.66 7.99 + 3.26
1F= 0.14; df= 2,14; P= 0.87
2F= 0.35; df= 2,14; P= 0.67
3F= 1.82; df= 2,14; P= 0.20
Table 5-2. Oviposition of Scapteriscus mole crickets in sand treated with S. scapterisci.
# Mole Width of egg Depth of egg
Treatment crickets that Number of eggs chamber (cm) (+ chamber (cm)
laid eggs (+ SEM) 1SE)2 SEM)3
Treated sand 3 33.5 + 17.99 4.5 0.42 15.5 + 1.
Untreated sand 5 24.0 25.45 5.0 + 0.60 19.5 2.
'F = 0.970; df =
2 F= 52.600; df
3F= 77.933; df=
2, 4; P
Table 5-3. Response of Scapteriscus vicinus, S. borellii, and S. abbreviatus to
Steinernema scapterisci nematodes versus sterilized sand.
Species tested # crickets selecting the y-tube arm1
S. scapterisci Sterilized sand %2
S. vicinus 3 7 2.1*
S. borellii 6 4 2.4*
S. abbreviatus 2 8 1.6**
All species combined 11 19 6.3
1Response of 10 individuals of each mole cricket species when given a choice between
two arms. *P<0.01, **P<0.005
Table 5-4. Response of Scapteriscus vicinus to Steinernema scapterisci nematodes
versus pesticides treated sand.
Pesticide tested Y-tube arm selected 1
S. scapterisci Insecticide No choice
Imidacloprid 5 1
Response of 7 mole crickets when given a choice between two arms.
More than 10 replicates are needed for statistical analysis.
SUMMARY AND CONCLUSIONS
Steinernema scapterisci is an insect parasitic nematode that has been formulated by
Becker Underwood as the biopesticide Nematac S. It differs from other commercially-
available nematodes used for mole cricket control by being able to reproduce in the host's
body and persisting in the soil after application. Thus, after being sprayed like a pesticide
to infested turfgrass, the nematodes may continually help to suppress mole crickets as a
Nematac S was originally marketed for use on pastures because insecticides were
not a cost effective control option. To expand the marketing and use of Nematac S, golf
courses, athletic fields, parks, lawns and other turfgrass areas were also considered. The
research conducted in this dissertation is relevant primarily to the golf course industry,
but results may be extrapolated into the other turfgrass sites.
The intensity of management on Florida golf courses ranges from high on private
courses to somewhat lower on municipal or public courses. Golfers, golf pros, and
superintendents tend to have little tolerance for damage on their greens, tees, and
fairways. Roughs and driving ranges, however, may receive less attention and may
therefore be more ideal areas for introducing or conserving natural enemies. This
research has demonstrated that S. scapterisci can survive on intensively managed golf
courses for more than ten years. Most of the insecticides (e.g., acephate, bifenthrin,
deltamethrin, fipronil, imidacloprid) used against mole cricket nymphs and adults do not
reduce nematode survival or infectivity. But, products used to control plant parasitic
nematodes would undoubtedly also kill beneficial nematodes. Perhaps this particular
problem, which many golf courses deal with, is why insect parasitic nematodes have not
been heavily used on golf courses in the past.
The beneficial effects of S. scapterisci increase in an additive fashion over time.
Steinernema scapterisci can survive and reproduce within the soil and can be transported
to new areas via mole cricket movement; therefore its benefits are seen year after year,
unlike pesticides which need to be reapplied. Golf courses unknowingly benefit from
nematode populations by an overall reduction in mole cricket populations over time. The
reduction in mole cricket populations would then reduce the pesticide applications
required for mole crickets possibly to the level of applying hot spot applications only.
Steinernema scapterisci is an important part of any mole cricket integrated pest
AMBIENT DATA AND TURFGRASS QUALITY DATA COLLECTED AT
GAINESVILLE GOLF AND COUNTRY CLUB AND IRONWOOD GOLF COURSE
Table A-1. Ambient data collected from Gainesville Golf and Country Club on dates of
mole crickets collections.
Air Temp.1 Rel. Humid.1 Soil Temp.1 Rainfall2
Date (0C) (%) (0C) (cm)
October 2001 20.2 68.0 21.1 0.3
November 2001 15.3 60.0 14.6 2.7
December 2001 13.6 75.7 16.1 3.8
January 2002 12.8 64.5 13.3 13.3
February 2002 19.6 72.0 16.4 2.8
March 2002 24.1 80.0 15.3 8.3
April 2002 21.1 74.5 21.1 1.0
May 2002 21.0 79.3 20.4 4.0
July 2002 23.9 68.0 23.3 13.8
August 2002 23.3 82.2 23.9 26.5
September 2002 25.0 68.0 25.6 12.8
October 2002 22.6 74.5 22.5 4.2
1 Average of monthly data taken on each collection date. Soil temp taken at 7.6 cm below
2 Average monthly rainfall value from data collected at the Gainesville Regional Airport.
Table A-2. Ambient data collected from Ironwood Golf Course on dates of mole crickets
collections. n/a indicates data not collected for that date.
Air Temp.1 Rel. Humid.1 Soil Temp1. Rainfall2
Date (OC) (%) (OC) (cm)
October 2001 24.9 61.3 23.7 0.3
November 2001 18.9 64.8 16.1 2.7
December 2001 15.0 80.4 15.0 3.8
January 2002 n/a n/a 13.1 13.3
February 2002 17.9 84.0 16.7 2.8
March 2002 16.8 66.5 16.1 8.3
April 2002 23.9 72.6 22.2 1.0
May 2002 18.5 94.3 20.9 4.0
July 2002 23.3 93.0 23.3 13.8
August 2002 24.2 74.0 24.6 26.5
September 2002 25.1 56.0 23.3 12.8
October 2002 22.6 60.5 24.0 4.2
November 2002 11.7 78.5 11.1 13.3
December 2002 13.3 93.0 10.0 18.3
January 2003 3.1 68.0 7.22 0.5
February 2003 10.6 60.0 5.0 16.8
March 2003 21.1 68.5 17.2 19.5
April 2003 16.2 76.0 17.2 4.1
May 2003 19.3 74.0 20.6 5.1
1 Average of monthly data taken on each collection date. Soil temp taken at 7.6 cm below
2 Average monthly rainfall value from data collected at the Gainesville Regional Airport.
Table A-3. Average turfgrass density ratings for treated and untreated plots on
Gainesville Golf and Country Club and Ironwood Golf Course. l=poor;
5=acceptable; 9=excellent. n/a indicates data not taken.
Gainesville Golf and Ironwood Golf Course
Collection Date treated untreated treated untreated
plots plots plots plots
October 2001 5.7 5.2 5.0 3.7
November 2001 7.7 7.6 6.2 4.4
December 2001 6.7 6.3 6.0 4.9
January 2002 5.7 5.7 6.0 4.8
February 2002 6.1 6.2 5.9 4.8
March 2002 6.8 5.9 5.0 4.3
April 2002 6.3 5.6 4.8 3.7
May 2002 6.5 5.4 5.4 3.8
July 2002 8.7 6.8 6.4 5.5
August 2002 5.3 5.5 5.9 5.1
September 2002 5.8 6.3 5.7 5.0
October 2002 4.9 4.6 5.6 5.0
November 2002 n/a n/a 5.2 5.1
December 2002 n/a n/a 6.2 4.8
January 2003 n/a n/a 5.3 3.4
February 2003 n/a n/a 5.5 4.6
March 2003 n/a n/a 4.6 3.6
April 2003 n/a n/a 4.6 3.6
May 2003 n/a n/a 4.5 3.4
DATA FROM ATHLETIC FIELD DEMONSTRATION SITES
Materials and Methods
A demonstration project was conducted on athletic field turfgrass. Methods were
similar to those in Chapter 2 of this dissertation; however fewer replicates were used due
to limited space. Nematodes are an important part of an athletic field IPM program
because they are a non-chemical way of reducing mole cricket populations. This in turn
reduces the exposure to children who use these fields.
The establishment and spread of S. scapterisci was monitored on two baseball
fields located in Sarasota, FL (Twin Lakes Park) and Altamonte Springs, FL (Eastmonte
Park). Both baseball fields were open to the public. The Sarasota field was built around
1975 and the Altamonte Springs field was built around 1970. The Sarasota field was
common bermudagrass (Cynodon dactylon [L.] Pers.) and the Altamonte Springs field
was bermudagrass (Cynodon dactylon x C. transvaalensis) var. Tifway. Both parks were
mowed at 1.91 cm. Neither park had previously received Steinernema scapterisci
Mole Cricket Monitoring
Three hot spots of mole cricket activity were located in each baseball outfield.
Linear pitfall traps (modified from Lawrence 1982, described in Chapter 2) were installed
in the ground at least 100 m apart. Each field contained two treated areas and one control
area. Traps on all sites were installed in September 2001.
Nematodes were released in the morning (approximately 0700). Nematodes were
applied in an aqueous suspension of 1 billion nematodes/ 378.5 L of water applied using
a boom sprayer calibrated at 40 L/1000 m2. The area treated was 20.1 x 20.1 m (404.7
m2) around each trap. Treated areas were irrigated with 0.6 cm of water before and 0.6
cm after application. The pre-treatment dates for Sarasota were 11,18 October 2001 and
11 October 2001 for Altamonte Springs. Nematodes were applied on 11 November 2001
at Sarasota and 25 October 2001 at Altamonte Springs. A second application of
nematodes was made on the Sarasota field 11 October 2002.
Pitfall traps were sampled to monitor infection levels and mole cricket abundance
using methods similar to Parkman et al. (1993a,b). At each 24 h sampling period the
buckets and arms were cleaned out and 3 to 5 cm of sand was placed into the inner
bucket. Traps were left for 24 h and all live mole crickets were collected. Mole crickets
were placed individually in 20 ml plastic scintillation vials (Fisher Scientific) with 1-2
drops of deionized water, capped and labeled and mailed via overnight courier delivery to
Gainesville, FL. The nematode doesn't move much in the soil and can't be identified
through soil samples, so adult and juvenile mole crickets with pronotal lengths > 4 mm
(Hudson and Nguyen 1989a) were collected from traps, using the same methods as in the
pretreatment sampling, and tested for infection weekly for the first 6 weeks post-
application and one to two times a month thereafter for 2 yr. Turf quality (density, color)
in the area immediately surrounding the pitfall traps was assessed (1 to 9 scale with 1 =
sparse or brown grass, 9 =dense or dark green grass). A second application of S.
scapterisci was made on 11 October 2002 at Sarasota due to low levels of infection in
collected mole crickets. The percentage of infected mole crickets was determined at 7
and 10 d after death under a dissecting scope (10 X). Steinernema scapterisci were
identified by Dr. Khuong Nguyen, Entomology and Nematology Department, University
Results and Discussion
It took approximately 8 wk for infection levels to reach 25% in the mole crickets
collected at the Sarasota site. Levels remained at or near this for about 1 yr post-initial
application. After the second application in October 2002 levels reached 25% (Figure B-
1) and remained at this level in the following spring mole cricket population (March and
April 2003). The baseball field had heavy rains and flooding as well as a non-functional
irrigation system in 2002. Infection level may have been higher if these factors had not
occurred. Very low levels of mole cricket damage/activity were observed in spring
through fall 2003 when compared to previous years. Levels of infection were also low in
the summer months due to the small size of the crickets present during these months (see
Chapter 2). A second application of nematodes may be necessary to reestablish
nematode populations high enough in the soil to result in infection levels of 15-30% in
collected mole crickets.
Data from the Altamonte Springs site was terminated early due to the very low
numbers of crickets (< 20) collected during the research period. The study on this site
was canceled in May 2002. Statistics presented in both graphs are comparisons of
monthly means (SAS Institute 2001).
Sarasota Athletic Field
Figure B-1. Average monthly infection rates at the Sarasota athletic field research site. Arrows indicate Steinernema scapterisci
applications. F=3.1212; df=24,92; P=0.0001
OCT 01 NOV 01 DEC 01 JAN 02 FEB 02 MAR 02 APR 02
Figure B-2. Average monthly infection rates at the Altamonte Springs athletic field research site. Arrow indicates Steinernema
scapterisci applications. F=9.35; df=6,15; P=0.002
PRELIMINARY CHECKLIST OF ARTHROPODS ASSOCIATED WITH GOLF
Below is a preliminary checklist of arthropods found in linear pitfall traps located
on Gainesville Golf and Country Club and Ironwood Golf Course in Gainesville Florida
from November 2001 through October 2003. List is considered preliminary and
incomplete due to limited time in which the identifications could be completed.
Class Order Family: subfamily Genus: species
Insecta Coleoptera Carabidae Omophron labiatum
Curculionidae Sphenophorus spp.
Elateridae 3 A'/ itihn, squamiger
Geotrupidae Peltotrupes profundus
Scarabaeidae Ataenius spp.
Dermaptera Labiduridae Labidura riparia
Lepidoptera Geometridae Mocis spp.
Noctuidae Herpetogramma phaeopteralis
Pyralidae Spodoptera frugiperda
Class Order Family: subfamily Genus: species
SCANNING ELECTRON MICROGRAPH PICTURES OF MOLE CRICKET
Scanning electron micrograph photographs were taken using a tungsten low
vacuum scanning electron microscope model JSM-5510LV (JEOL-USA, Peabody, MA)
to determine if any significant sensory hairs, pores, or other morphological aspects were
apparent on mole crickets. Pictures were taken of dried, curated mole crickets focusing
on the antenna of an adult male and one adult female, a female mid-tarsomere, and a
female labial palpomere. These photographs are only an initial look at mole cricket
sensory organs and more in-depth photographs should be taken for future study.
Figure D-1. SEM photograph of a female Scapteriscus vicinus antennal mid-section.
Figure D-2. SEM photograph of a male Scapteriscus vicinus antennal mid-section.
Figure D-3. SEM photograph of a female Scapteriscus vicinus mid-tarsal claw.
Figure D-4. SEM photograph of a female Scapteriscus vicinus labial palpomere.
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