Effects of Sperm Conjugation and Dissociation on Sperm Viability In Vitro

Sperm conjugation is an unusual variation in sperm behavior where two or more spermatozoa physically unite for motility or transport through the female reproductive tract. Conjugation has frequently been interpreted as sperm cooperation, including reproductive altruism, with some sperm advancing their siblings toward the site of fertilization while ostensibly forfeiting their own ability to fertilize through damage incurred during conjugate break-up. Conversely, conjugation has been proposed to protect sensitive regions of spermatozoa from spermicidal conditions within the female reproductive tract. We investigated the possibility of dissociation-induced sperm mortality and tested for a protective function of conjugation using the paired sperm of the diving beetle, Graphoderus liberus. Sperm conjugates were mechanically dissociated and exposed to potentially damaging tissue extracts of the female reproductive tract and somatic tissue. We found no significant difference in viability between paired sperm and dissociated, single sperm. The results further indicate that the reproductive tract of female G. liberus might not be spermicidal and conjugation is not protective of sperm viability when damaging conditions do exist. Our results support the interpretation that, at least in some taxa, sperm conjugation is neither protective nor damaging to sperm viability

Biological controls investigated to aid management of olive fruit fly in California

The widespread and rapid establishment of the olive fruit fly in California required immediate changes in integrated pest management (IPM) programs for olives. After finding that resident natural enemies did not provide adequate control, researchers began a worldwide search for parasitoids, with exploration in the Republic of South Africa, Namibia, India, China and other countries. Parasitoids were shipped to California, and most were studied in quarantine to determine the best species for release. Two parasitoid species — Psyttalia lounsburyi and Psyttalia humilis — are now being released throughout the state’s olive-growing regions, and researchers are studying their effectiveness

Intrasexual Aggression in the Stick Insects Diapheromera Veliei and D. Covilleae and Sexual Dimorphism in the Phasmatodea

Volume: 85Start Page: 395End Page: 40

Arthropods Attracted to Luminous Fungi

Volume: 88Start Page: 383End Page: 39

A Kleptoparasitic Cecidomyiid and Other Flies Associated With Spiders

Spiders and their webs are predictable sources of insect cadavers. A small number of animals regularly exploit this resource, either as kleptoparasites or commensals, depending on whether symbionts compete for the same prey (see Robinson and Robinson, 1977, for more detailed terminology). Among the thieves are specialized spiders (citations in Vollrath 1979a, 1979b), mature male and juvenile spiders (Stowe 1978, citations in Nyffeler and Benz 1980), Hemiptera (Davis and Russell 1969), a hummingbird (takes webbing in addition to small insects, Young 1971), panorpid scorpion-flies (Thornhill 1975), Lepidoptera larvae (Robinson 1978), wasps (Jeanne 1972), damselflies (Vollrath 1977), and a handful of flies (reviews in Knab 1915; Bristowe 1931, 1941; Lindner 1937; Richards 1953; Robinson and Robinson 1977). Only a few of the reports on Diptera kleptoparasites originate from North America (McCook 1889, Frost 1913, Downes and Smith 1969). With a single exception (Downes and Smith 1969), all of the previously described kleptoparasitic flies belong to the Brachycera and Cyclorrhapha. We report here on a surprisingly diverse kleptoparasitic Diptera fauna in north central Florida with a cecidomyiid (Nematocera) as its dominant member

Depth of Pupation and Survival of Fruit Fly (\u3ci\u3eAnastrepha\u3c/i\u3e spp.: Tephritidae) Pupae in a Range of Agricultural Habitats

In central Veracruz State, Mexico, tephritid fruit fly pupae are commonly attacked by ants, staphylinid beetles, and other predators. Excavations in 2 sites with different soil characteristics revealed that Anastrepha spp. (Diptera: Tephritidae) larvae typically burrowed no \u3e2 cm before pupating and rarely burrowed \u3e5 cm. At 4 field sites, pupae of the most commonly encountered local Anastrepha sp. (A. obliqua, ludens, and striata or fraterculus) were placed on the soil surface and at depths of 2.5 and 5 cm and were subsequently sampled daily for 10 d. Pupae on the surface invariably disappeared at a greater rate than those under the surface. There was no difference in the disappearance rate of pupae buried at 2.5 and 5 cm, suggesting that larvae would gain no benefit by pupating at depths below those encountered in nature. The rate of disappearance of the buried pupae differed considerably among the sites. At the end of the sampling period the proportion of pupae remaining ranged from 15 to 70%. Differences in the species of predators present and soil characteristics may have contributed to these differences in disappearance. Pupae disappeared at the highest rate in a site with dry loose soil. It was lowest in sites with damp clay soils characterized by fine particle size and small interparticle spaces