Abundance and host associations of parasitoids attacking frugivorous drosophilids on Iriomote-jima, a subtropical island of Japan

Biljana Novković,Hideyuki Mitsui,Masahito T Kimura,Ayako Oikawa,Yusuke Murata

doi:10.14411/eje.2012.065

Abstract

To understand the factors governing the diversity, abundance and host associations of parasitoids attacking frugivorous drosophilid flies on Iriomote-jima, a subtropical island of Japan, we monitored parasitism on several occasions over the period 2003-2009. Fifteen drosophilid and 12 parasitoid species were recorded. Three species of Drosophila, D. bipectinata, D. albomicans and D. takahashii, bred abundantly in banana baits, though their abundance varied between years and seasons. Frequent parasitoid species were Asobara japonica, A. pleuralis (Braconidae), Leptopilina ryukyuensis and L. pacifica (Figitidae). L. victoriae was recorded only in December 2003. In addition, host acceptance and host suitability of the four most frequently recorded parasitoid species were studied in the laboratory. Most parasitoid and drosophilid species showed species-specific associations with more than one antagonist species, suggesting that they have been subjected to complex coevolutionary interactions. In addition, host range of most of the parasitoid species included one of the three major Drosophila species, suggesting that the abundance of potential hosts is one of the factors determining the evolution of parasitoid host use.

Highlights

Field studies that focus on host-parasitoid relations and the changes and variations that occur in host-parasitoid communities in space and time, contribute a great deal to our understanding of host-parasitoid coevolutionary interactions
These are important for analyzing population dynamics of both hosts and their parasitoids, and essential when assessing the evolution of host resistance and parasitoid virulence in multi-species hostparasitoid systems
Fifteen drosophilid and 12 parasitoid species were recorded in the field survey (Tables 2 and 3)

Summary

INTRODUCTION

Field studies that focus on host-parasitoid relations and the changes and variations that occur in host-parasitoid communities in space and time, contribute a great deal to our understanding of host-parasitoid coevolutionary interactions. Parasitoids in return evolve ways to cope with host defenses, such as sticky eggs, virus-like particles and venom virulence factors (Fleury et al., 2009) Both host resistance and parasitoid virulence are thought to be graded traits, which form clines and mosaics in natural communities, based on local selective forces (Boulétreau & Fouillet, 1982; Carton & Nappi, 1991; Kraaijeveld & van Alphen, 1994, 1995; Kraaijeveld et al, 1998; Kraaijeveld & Godfray, 1999). We used laboratory experiments to study the host acceptance and host suitability for abundant drosophilid and parasitoid species Based on these results we discuss the differences in the host-parasitoid communities recorded on Iriomote-jima, in central Japan and other previously surveyed regions

MATERIAL AND METHODS

21–27 September

RESULTS

DISCUSSION