Parasites can influence various aspects of host reproduction and mating behavior. One important component of invertebrate reproduction that may be affected is spermatophore production. In the cricket, Gryllodes sigillatus, males transfer a two-part spermatophore to female containing a sperm-filled ampulla and a gelatinous spermatophylax. Here we experimentally test the impact of a sexually transmitted nematode on male spermatophylax production. Since host mating success is directly linked to parasite reproductive success, we would expect the parasite to favor increased sexual activity. Increased sexual activity can be achieved via induced sterility, e.g., attenuated spermatophore production. Our results show that nematode parasitism in the hindgut of male crickets has an adverse affect on spermatophylax production. Infected males produce a significantly smaller spermatophylax than uninfected males; this effect was more apparent for smaller males. Spermatophylax size is inversely correlated with intensity of infection. The replacement time between the first and second spermatophylax does not differ significantly between infected and uninfected males. The parasite-induced change in spermatophylax size has potential consequences for female mating behaviour, parasite-mediated sexual selection, and parasite transmission rate.
Species 1: Orthoptera Gryllidae Gryllodes sigillatus (decorated cricket, Indian house cricket)
Species 2: Diplogasterida Mehdinema alii
Keywords: sexually transmitted parasites, nuptial food gift
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