Gryllus integer

Gryllus integer, commonly known as the western trilling cricket, is one of many species of field cricket (subfamily Gryllinae) in the genus Gryllus. It is called the "triller" field cricket because its song is nearly continuous rather than broken into discrete chirps.[1] G. integer can be found in parts of the Western United States, having been recorded from Oregon, California, Arizona and New Mexico.[2]

Gryllus integer
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Orthoptera
Suborder: Ensifera
Family: Gryllidae
Subfamily: Gryllinae
Tribe: Gryllini
Genus: Gryllus
Species:
G. integer
Binomial name
Gryllus integer
Scudder, 1902

Morphology

Gryllus integer can be medium to large in size, ranging from 17.1- 24.0 mm, it is macropterous(large-winged), its head and pronotum are jet black and tegmina is light brown.[3]

Habitat

Typical of many field crickets, G. integer can be found living in cracks or burrows in the ground in disturbed areas such as roads or by buildings, and around human habitation.[3]

Song production

Gryllus integer has a unique song known as a rapid thrill.,[3] which is produced by tegminal (forewing) stridulation.[2][4] These displaying male crickets prefer to call from warmer sites and it has been found that their micro-habitat choice based on temperature can influence their mating calls.[5] Male song varies in duration of uninterrupted trilling. Males use this call to attract sexually receptive females who tend to preferentially move toward males with longer calling bouts (periods of calling that contain no pause greater than 0.10 s in real time), although female mate preference can vary.[6] These males tend to fight intensely and stridulate their wings more when trying to acquire females. Sexually mature males tend to be more aggressive and heavier than lighter males which have not yet produced a spermatophore.[7] The calling song of G. integer attracts females and results in spacing between mates, but it also attracts the parasitoid female fly Euphasiopteryx ochracea. This parasitoid fly lays its larvae on the surface of the cricket and burrows into its body.[8]

Variation

Male G. integer from Davis, California, do not trill but rather produce fast trains of chirps containing 2 or 3 syllables per chirp with a pause between chirps approximately 30ms long, but most commonly with 3. Females tend to respond more to 2 syllables then 3. Arizona populations of G.integer call exclusively with 2 syllables per chirp. Californian G. integer are relatively intolerant of increased syllable numbers. Californian G. integer prefer particular chirp pauses (24-36 ms) but accepted somewhat longer ones (up to 70 ms).[9]

Sperm competition

Sperm competition is the competition that occurs when females store sperm, of varying males, in their spermatheca and use this sperm to fertilize their eggs. This type of competition is prevalent when females mate more than once in which they store sperm in a viable condition and have sperm from previous matings present when they re-mate[10] Field crickets (Gryllidae) show all of the prerequisites for sperm competition. Females mate repeatedly with different males, store the sperm in a spermatheca and sperm from previous matings is viable in the spermatheca when females re-mate.[11] Males guard females after mating which also suggests sperm competition.[12]

Predators

This species of cricket is popular for use as a food source for insectivorous animals like spiders, reptiles, rodents, bats and birds.[9] In addition, the tachinid fly Ormia ochracea is known to parasitize G. integer.[13] O. ochracea uses the mating call of G. integer to locate the host, then the female fly deposits larvae on the host.[14]

Anti-predator response

In order to evade predators, adult G. integer engage in a behavior known as "freezing." This anti-predator behavior appears to have a genetic and/or maternal effect[9]

gollark: So some stuff won't work very well.
gollark: The K80 is actually two K40s glued together.
gollark: Move Mercury into Earth orbit.
gollark: You'd have to bring a bunch of servers over and slowly mirror everything.
gollark: Or just upload your brain to computers™, which is definitely a good idea.

References
  1. Walker, T. 1998. Trilling field cricket in a zone of overlap. Ann Entomol Soc Am, 91(2), 175-184.
  2. Hedrick, A. 1986. Female preferences for male calling bout duration in a field cricket. Behav Ecol Sociobiol, 19, 73-77.
  3. Weissman, D. 1980. Field crickets (Gryllus and Acheta) of California and Baja California, Mexico (Orthoptera: Gryllidae: Gryllinae). American Entomological Society, 106, 327-356.
  4. Loher, W. and Dambach, M. 1989. Reproductive behavior. In Cricket Behavior and Neurobiology (ed. Huber, F., Moore, T. E., and Loher, W.), pp. 43-82. Ithaca, NY: Cornell University Press., ISBN 0-8014-2272-8
  5. Hedrick, A. V., Perez, P., & Lichti, N. 2002. Temperature preferences of male field crickets (Gryllus integer) alter their mating calls. J Comp Physiol A, 188, 799-805.
  6. Hedrick, A., & Weber, T. 1998. Variance in female responses to the fine structure of male song in the field cricket, Gryllus integer. Behav Ecol, 9, 582-591.
  7. Dixon, K., & Cade, W. 1986. Some factors influencing male- male aggression in the field cricket Gryllus integer (time of day, age, weight and sexual maturity). Anim. Behav, 34, 340-346
  8. Cade, W. H. 1975. Acoustically orienting parasitoids: fly phonotaxis to cricket song. Science, 190, 1312-1313
  9. Hedrick, A. 2013. Family effects on anti-predator behavior in the field cricket, Gryllus integer. J. Insect Behav, 26, 832-836
  10. Parker, G. A.1970. Sperm competition and its evolutionary consequences in the insects. Biol Rev Camb Philos Soc, 45, 525-567
  11. Evans, A. R.1983. A study of the behavior of the Australian field cricket, Teleo-gryllus commodus (Walker) (Orthoptera:Gryllidae) in the field and in habitat stimulations. Z Tierpsychol, 62, 269-290
  12. Alexander, R. D., & Otte, D. 1967. The evolution of genitalia and mating behavior in crickets (Gryllidae) and other Orthoptera. Museum of Zoology, University of Michigan, Miscellaneous Publications No. 133. 1-62, suggesting the occurrence of sperm competition
  13. Lehmann, Gerlind U.C. (January 2003). "Review of Biogeography, Host Range and Evolution of Acoustic Hunting in Ormiini (Insecta, Diptera, Tachinidae), Parasitoids of Night-calling Bushcrickets and Crickets (Insecta, Orthoptera, Ensifera)". Zoologischer Anzeiger - A Journal of Comparative Zoology. 242 (2): 107–120. doi:10.1078/0044-5231-00091. ISSN 0044-5231.
  14. Cade, W. (1975-12-26). "Acoustically Orienting Parasitoids: Fly Phonotaxis to Cricket Song". Science. 190 (4221): 1312–1313. doi:10.1126/science.190.4221.1312. ISSN 0036-8075.
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