No abstract

Ganaspis individuals parasitizing Drosophila suzukii (Matsumura), a pest of fruit crop, were examined for host use and molecular and morphological differences from those attacking D. lutescens Okada and some other Drosophila species that breed on fermenting fruits. Wild cherry fruits were collected in the suburbs of Tokyo, and drosophilid pupae obtained from these fruits were examined for parasitism.Drosophila suzukii was the only drosophilid species infesting fresh wild cherry fruits, and Ganaspis individuals were the major parasitoids attacking D. suzukii in wild cherry fruits. In parasitism experiments, these Ganaspis individuals parasitized D. suzukii larvae in fresh cherry fruits, but did not parasitize those in Drosophila medium. In addition, they did not parasitize larvae of some other fruit-feeding Drosophila species even when these occurred in fresh cherry fruit. These Ganaspis individuals parasitizing D. suzukii were different from those parasitizing D. lutescens and some other drosophilids in nucleotide sequences of the COI gene, as well as in ITS1 and ITS2.

The diversity and host associations of parasitoids attacking mycophagous drosophilids were studied in Tokyo (the warm-temperate region) and Sapporo (the cool-temperate region) in Japan. Field collections were carried out using traps baited with mushrooms in May, June, September and October, 2009 in Tokyo and in July and August, 2010 in Sapporo. The major drosophilid species that emerged from mushroom baits was Drosophila bizonata in Tokyo and D. orientacea in Sapporo. In total, 13 parasitoid species emerged from drosophilids occurring in mushroom baits, and 11 of them were larval parasitoids belonging to Braconidae and Figitidae. Among the 11 larval parasitoids, 10 were collected in Tokyo, while only two were collected in Sapporo. It is not known why their diversity differed so much between these two regions. Four of the 11 larval parasitoids have also been recorded from drosophilid larvae occurring in fruits (banana). The use of these two habitats (mushrooms and fruits) by these four species seems to reflect the occurrence (i.e. resource use) of their suitable hosts. On the other hand, most larval parasitoids from Tokyo attacked D. bizonata, and two larval parasitoids from Sapporo attacked D. orientacea, suggesting that the abundance of potential hosts is one of the important factors affecting their host use.

Wasps of the genus Leptopilina (Hymenoptera: Figitidae) are larvo-pupal parasitoids of Drosophila species.Here we report three putative thelytokous species of this genus from Japan, with description of two new species L. tokioensis and L. tsushimaensis, which have been recorded from central Japan and Tsushima, respectively. Another thelytokous species is L. longipes occurring in northern Japan, although its European populations are assumed to be arrhenotokous. Preliminary phylogenetic analyses suggest the present three species are diversified from one another and also from the other Leptopilina species. These three thelytokous species are infected by B-supergroup Wolbachia as in European thelytokous species, L. clavipes and L. australis. The evolution of these thelytokous species is discussed based on the present and previous results, and the occurrence and distributions of Leptopilina species in Japan and surrounding regions are briefly reviewed.