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Brief Summary

    Scapteriscus: Brief Summary
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    Scapteriscus is a genus of insects in the family Gryllotalpidae, the mole crickets. Members of the genus are called two-clawed mole crickets. They are native to South America. Some species have arrived in other regions (by flight or as contaminants of ship ballast or cargoes), including parts of North America, where some have become invasive and have become established as pests.

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Comprehensive Description

    Genus Scapteriscus (two-clawed mole crickets) in North America north of Mexico
    provided by Singing Insects of North America (text)
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    Members of this genus have two blade-like claws (dactyls) on each foretibia and the auditory tympanum is exposed. The foretrochanter is armed with an elongate blade. The hindtibia has 3-6 long spines along its upper inner margin.

    Our three species in this genus are native to South America and first became established in North America more than 90 years ago, apparently from stowaways in ships' ballast. Maps of when and where they were introduced and how they spread are on the species pages and in Walker & Nickle (1981).

    Life cycles

    Two-clawed mole crickets require a year or less for a generation. In the colder parts of their ranges they overwinter both as adults and large nymphs. Eggs are laid in clutches of 25 to 60 in small ovoid chambers (4 x 3 cm) 9 to 30 cm below the surface.

    Economic importance

    Members of this genus are the most damaging crickets in the New World. In the southeastern United States tawny mole crickets (S. vicinus) are major pests of established lawns and pastures, causing annual losses of $10's of millions. Short-winged mole crickets (S. abbreviatus) do the same type of damage but are much more restricted geographically. Southern mole crickets (S. borellii) feed largely on animal matter and avoid established turf; however, they damage seedlings in newly planted lawns, gardens, and fields.

    Biological control

    Because our pest mole crickets were introduced and occurred in much greater numbers here than in their homeland, University of Florida researchers concluded that they might be controlled by classical biological control--that is, by introducing natural enemies that had been left behind when they immigrated from South America. Of the enemies that proved promising because of their host specificity, three have been successfully introduced, and have substantially reduced Scapteriscus populations. Steinernema scapterisci is a nematode that kills mole crickets by introducing lethal microbes (Parkman et al 1993). Ormia depleta is a tachinid fly that homes on the calling songs of male mole crickets and deposits living larvae that enter and consume mole crickets (Frank et al 1996). Larra bicolor is a sphecid wasp that chases a mole cricket from its burrow, subdues it with a sting and glues an egg at the base of a middle leg. The mole cricket recovers but the egg becomes a larva that feeds on the cricket while attached externally and eventually kills its host and consumes the remains (Walker 1984).

    Flights

    Large numbers of tawny and southern mole crickets fly during the early evening of warm days each spring. One result of such flights is that new lawns and fields are infested and pesticide-treated ones are re-infested. Another result is that females find mates by homing to the appropriate calling song and landing near the entrance to the caller's burrow.

    Some important features of the flights are not adequately understood. Males and mated females, as well as virgin females, often terminate their flights by homing to conspecific calling song, and the same individual may fly and home repeatedly over a period of several weeks. Available evidence suggests that many flights terminate near their starting points and that in heavily infested fields a minority of the males call each evening. Pair formation and sexual competition in these species deserve further study. Most flights probably involve more than colonizing new or better fields or finding a willing source of conspecific sperm. T.G. Forrest (1983) has shown that calling males vary greatly in their attractiveness to females. On an evening when one calling male attracts no female, another, calling nearby, may attract more than 20! (He cannot service so many--Forrest prevented them from reaching the male.) Male attractiveness correlates with loudness of the calling song. Loudness correlates with both male size and soil moisture, which in turn are indicative of male quality and habitat quality. Scientists have exploited the attractiveness of loud calls by broadcasting simulated mole cricket sounds more than 30 times as powerful as the loudest male and have collected as many as 8000 mole crickets at a single sound source in a single evening.

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    References

    • Walker TJ, Nickle DA. 1981. Introduction and spread of pest mole crickets: Scapteriscus vicinus and S. acletus reexamined. Ann. Entomol. Soc. Am.74: 158-163.
    • Parkman JP, Hudson WG, Frank JH, Nguyen KB, Smart, GC Jr. 1993. Establishment and persistence of Steinernema scapterisci, Rhabditida: Steinernematidae, in field populations of Scapteriscus spp. mole crickets, Orthoptera: Gryllotalpidae. J. Entomol. Sci. 28: 182-190.
    • Frank JH, Walker TJ, Parkman JP. 1996. The introduction, establishment, and spread of Ormia depleta in Florida. Biol. Control 6: 368-377.
    • Walker TJ. 1984. Biology of pest mole crickets: systematics and life cycles. Univ. Fla. Agric. Exp. Sta. Bull. 846: 3-10.
    • Forrest TG. 1983. Calling songs and mate choice in mole crickets. In: Gwynne DT, Morris GK, editors. Orthopteran mating systems: sexual competition in a diverse group of insects. Boulder CO: Westview. Pp. 185-204.

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    Scapteriscus text
    Scapteriscus
    provided by wikipedia

    Scapteriscus is a genus of insects in the family Gryllotalpidae, the mole crickets. Members of the genus are called two-clawed mole crickets.[1] They are native to South America.[2] Some species have arrived in other regions (by flight or as contaminants of ship ballast or cargoes), including parts of North America, where some have become invasive and have become established as pests.[1]

    Description

    These are medium-sized or large mole crickets characterized by the structures on their forelegs: two sharp claws and a blade-like process with a sharp flange or tooth. Other mole crickets have three or four claws.[3] Like other mole crickets, these burrow in the ground and the males produce calls with their tegmina.[4]

    Impacts

    Scapteriscus species have been called "the most damaging crickets in the New World".[1] The major pest species include Scapteriscus abbreviatus, S. borellii, S. didactylus, and S. vicinus.[5] These burrowing insects are pests of lawns, pastures, and gardens.[1] Some species feed on plant roots and seedlings,[6] while others are carnivorous and damage turf with their digging activity.[7] They are notorious in the southeastern United States, where they have been called "the most damaging insect pests of turf and pasture grasses in Florida".[2] S. didactylus is invasive in Australia, where it damages turf, especially on golf courses, and attacks crops such as rice and peppers.[8]

    In French Guiana, S. didactylus is a predator of the eggs of the critically endangered leatherback sea turtle (Dermochelys coriacea).[9]

    Agents of biological pest control have proved effective for these mole crickets.[10] The nematode Steinernema scapterisci kills the mole cricket by carrying bacteria into its body, introducing an overwhelming infection.[1][11] The tachinid fly Ormia depleta is a parasitoid that leaves its carnivorous larva on the body of the mole cricket[12][13] The crabronid wasp Larra bicolor (family Crabronidae) catches the mole cricket and sticks an egg to it. When the larva emerges, it consumes the mole cricket alive.[14][1]

    Such a pity, but this article is all outdated - it refers mainly to the 3 species in Florida but ignores that they have been transferred to the new genus Neoscapteriscus. See the Wikipedia article on mole crickets for a more correct presentation.

    Diversity

    In 2003 there were 21 species in the genus.[4] More have since been described.[3]

    Species include:[4][5]

    Two species of Scapteriscus were separated and placed in the new genus Indioscaptor.[4]

    References

    1. ^ a b c d e f Genus Scapteriscus. In: Walker, T. J. Singing Insects of North America. Entomology and Nematology. University of Florida, IFAS.
    2. ^ a b Parkman, J. P. and J. H. Frank. (1992). Infection of sound-trapped mole crickets, Scapteriscus spp., by Steinernema scapterisci. Florida Entomologist 75(1) 163-65.
    3. ^ a b c d Rodríguez, F. and S. Heads. (2012). New mole crickets of the genus Scapteriscus Scudder from Colombia (Orthoptera: Gryllotalpidae; Scapteriscinae). Zootaxa 3282, 61–68.
    4. ^ a b c d Nickle, D. A. (2003). A revision of the mole cricket genus Scapteriscus with the description of a morphologically similar new genus (Orthoptera: Gryllotalpidae: Scapteriscinae). Transactions of the American Entomological Society 129(3–4) 411–485.
    5. ^ a b Names, Origins, and Distribution of Mole Crickets. Entomology and Nematology. University of Florida, IFAS.
    6. ^ Tawny Mole Cricket, S. vicinus. Entomology and Nematology. University of Florida, IFAS.
    7. ^ Southern Mole Cricket, S. borellii. Entomology and Nematology. University of Florida, IFAS.
    8. ^ Rentz, D. C. F. (1995). The changa mole cricket, Scapteriscus didactylus (Latreille), a New World pest established in Australia (Orthoptera: Gryllotalpidae). Australian Journal of Entomology 34(4) 303-06.
    9. ^ Maros, A., et al. (2003). Scapteriscus didactylus (Orthoptera, Gryllotalpidae), predator of leatherback turtle eggs in French Guiana. Marine Ecology Progress Series 249,289-96.
    10. ^ Frank, J. H. and Walker, T. J. (2006) Permanent control of pest mole crickets (Orthoptera: Gryllotalpidae: Scapteriscus) in Florida. American Entomologist 52: 138-144 [1]
    11. ^ Smart, G. C. (1994). Steinernema scapterisci, a nematode parasite of mole crickets, Scapteriscus spp. Nematology Circular No. 206. Florida Department of Agriculture and Consumer Services.
    12. ^ Frank, J.H., Walker, T.J., Parkman, J.P. 1996. The introduction, establishment and spread of Ormia depleta in Florida. Biological Control 6: 368-377.
    13. ^ Walker, T.J., Parkman, J.P., Frank, J.H., Schuster, D.J. 1996. Seasonality of Ormia depleta and limits to its spread. Biological Control 6: 378-383.
    14. ^ Frank, J.H. and Sourakov, A. 2012. Larra wasps, mole cricket hunters. http://entnem.ifas.ufl.edu/creatures/beneficial/Larra_wasps.htm
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