Different effects of endoparasites (big-headed flies) on reproduction between male and female hosts (leafhoppers)

The big-headed fly, Eudorylas sp. (Diptera: Pipunculidae), is an endoparasite of the leafhopper, Bothrogonia ferruginea (Homoptera: Cicadellidae). Both parasite and host have univoltine life-cycles. The leafhoppers eclose to adults in summer and so overwinter. In spring, they mate and oviposit. The flies overwinter inside their hosts at the endoparasitic larval stage. In spring, fully-grown larvae emerge from the hosts and pupate. Adult flies probably lay eggs inside the larvae of hosts. Parasitized larvae grow to be smaller adults, particularly in forewing size, than unparasitized ones. All hosts die soon after emergence of the endoparasitic larva. The non-lethal effects of endoparasitism, however, differ between male and female hosts. Infected females are always sterile due to undeveloped ovaries, but the males produce sperm normally and seem to mate. Such asymmetric effects of parasitism on females should promote greater ability to resist parasitization in females than in males. However, the severity of parasitism did not differ between the sexes.