Sexually transmitted nematodes affect spermatophylax production in the cricket, Gryllodes sigillatus

Parasites can influence various aspects of host reproduction and mating, including spermatophore production. In the cricket, Gryllodes sigillatus, males transfer to females a two-part spermatophore containing a sperm-filled ampulla and a gelatinous spermatophylax (nuptial gift). Here we investigate the effects of a sexually transmitted nematode on male spermatophylax production. Sexually transmitted diseases (STDs) have the potential to reduce host fertility or fecundity in insect hosts. To our knowledge this is the first empirical study on the effects of an insect STD on the reproductive physiology of a male host. Our results indicate that infected males produced significantly smaller spermatophylaces than healthy males; this effect was more apparent for smaller males. Spermatophylax size was inversely correlated with the intensity of infection. Spermatophylax replacement time, the time between producing the first and second spermatophylax, did not differ significantly between infected and healthy males. This parasite-mediated reduction in spermatophylax size may be a direct consequence of the physiological stress of parasitism or parasite manipulation. Copyright 2005.decorated cricket; nematode; parasitism; sexually transmitted parasites; spermatophore; spermatophylax