Scapteriscus

Abstract: The first successful inoculative releases of an entomopathogenic nematode, Steinernema scapterisci Nguyen and Smart, for the control of exotic pests, Scapteriscus spp. mole crickets, were made at three pasture sites in Alachua County, Florida in 1985. Based on the evaluation of field-collected crickets, the nematode was established at all sites and persisted for over 5 years. Mean yearly percentage of infected crickets ranged from 0 to 21.4% for individual release sites. Mean adult infection level for all years combined, 10.9%, was significantly greater than that for nymphs (2.5%) and infection levels for Scapteriscus borellii Giglio-Tos, 12.7%, was significantly greater than that for Scapteriscus vicinus Scudder (4.5%) for all years combined. Although 24 h trap catch results indicate mole cricket populations were significantly reduced, the nematode's effect on pest abundance could not be adequately assessed because of the variation in trap catch results and inadequate knowledge about the relationship bet...

Abstract: Neither of the mole crickets most damaging to turf, pastures, and crops in southeastern United States is taxonomically what it has been thought to be. Scapteriscus vicinus Scudder, also called “changa” or “Puerto Rican mole cricket,” is distinct in calling song and interdactyl distance from the species known by the same name in Puerto Rico. Therefore its introduction at Brunswick, GA, ca. 1899, was from some other source. By 1960 its U.S. distribution included all of Florida, southern Georgia, and southernmost South Carolina. No additional spread has been reported during the past 20 years. Scapteriscus acletus Rehn and Hebard, long believed native to southeastern United States, was introduced at Brunswick, Georgia, ca. 1904. It was apparently introduced anew at Charleston, SC (ca. 1915), Mobile, AL (ca. 1919), and Port Arthur, TX (ca. 1925). Variations in pronotal color patterns suggest that the Charleston and Port Arthur introductions had a different origin than the Brunswick and Mobile introductions. By 1960, acletus had spread throughout Florida and southern Georgia, as far north as southern North Carolina, and as far west as eastern Louisiana; it had also occupied a large disjunct area in western Louisiana and eastern Texas. It has since spread to central Louisiana and been collected at scattered localities northward. Neither S. vicinus nor S. acletus reached peninsular Florida prior to 1925, but Scapteriscus abbreviatus Scudder, a flightless species of minor pest status, was introduced at six coastal cities of peninsular Florida, as well as at Brunswick, Georgia, prior to 1925. The homelands of U.S. Scapteriscus spp. should be located and their pathogens, parasites, and predators studied as potential biological control agents.

Abstract: Male crickets produce calling songs that function to attract mates. Sound is produced when membranes of the wings are caused to vibrate during stridulation. Sound fields were measured for three species of crickets. Two species of mole crickets, Scapteriscus acletus and s. vicinus, call from within burrows constructed in the soil. Sound fields of the mole crickets were hemispherical and the power output averaged 4 μW (N = 22, range 2–22 μW). Power output was dependent upon male size and moisture content of soil surrounding the burrow. Efficiency of sound production was estimated to be less than 0.2%. Sound fields of a species of tree crickets, Oecanthus quadripunctatus, approximated that of a doublet source. Power output ranged from 2–17 μW (N = 6) and efficiency was estimated at about 1%.

Abstract: Females of ormiine tachinids fly to their hosts' calling songs and deposit larvae on the host or nearby. Two species,Ormia ochracea (Bigot) andO. depleta (Wiedemann), were reared for at least 8 generations, making them the first ormiines to be laboratory-propagated. Both were reared on natural hosts:Gryllus spp. field crickets (principallyG. rubens) forO. ochracea, andScapteriscus spp. mole crickets forO. depleta. Commercially rearedAcheta domesticus tested as hosts were less satisfactory. Hosts were parasitized manually or by confinement with flies or planidia (infective larvae). Transparent, cylindrical, sleeved cages were designed to accommodate parasitized hosts and pupae and adults ofO. ochracea. Cages were joined to allowO. ochracea to cycle through its stages with minimum handling and care. Parasitized hosts and pupae ofO. depleta were held in containers of damp sand; adults were held in cages developed forO. ochracea. Adults of both species were maintained on applesauce, sugar cubes, powdered milk, and water. The life cycle ofO. ochracea was about 31 days and ofO. depleta about 36 days, with the principal difference being the time required for planidia to complete development. InO. ochracea the adults emerged synchronously but inO. depleta males preceded females. In both species sex ratio was generally I: 1 and females lived slightly longer than males.O. depleta from our laboratory colony have been released for biological control of mole crickets.