Potential host ranges of three Asian larval parasitoids of Drosophila suzukii

Brian N. Hogg,Xingeng Wang,Antonio Biondi,Kent M. Daane

doi:10.1007/s10340-021-01368-1

Abstract

Asobara japonica (Hymenoptera: Braconidae), Ganaspis brasiliensis and Leptopilina japonica (Hymenoptera: Figitidae) are Asian larval parasitoids of spotted wing drosophila, Drosophila suzukii (Diptera: Drosophilidae). This study evaluated these parasitoids’ capacity to attack and develop from 24 non-target drosophilid species. Results showed that all three parasitoids were able to parasitize host larvae of multiple non-target species in artificial diet; A. japonica developed from 19 tested host species, regardless of the phylogenetic position of the host species, L. japonica developed from 11 tested species; and G. brasiliensis developed from only four of the exposed species. Success rate of parasitism (i.e., the probability that an adult wasp successfully emerged from a parasitized host) by the two figitid parasitoids was low in hosts other than the three species in the melanogaster group (D. melanogaster, D. simulans, and D. suzukii). The failure of the figitids to develop in most of the tested host species appears to correspond with more frequent encapsulation of the parasitoids by the hosts. The results indicate that G. brasiliensis is the most host specific to D. suzukii, L. japonica attacks mainly species in the melanogaster group and A. japonica is a generalist, at least physiologically. Overall, the developmental time of the parasitoids increased with the host’s developmental time. The body size of female A. japonica (as a model species) was positively related to host size, and mature egg load of female wasps increased with female body size. We discuss the use of these parasitoids for classical biological control of D. suzukii.

Highlights

Classical biological control is a useful strategy for invasive pest species when effective natural enemies are lacking in the invaded range (Hajek et al 2016; Van Driesche et al 2010)
Ganaspis brasiliensis developed from only three non-target species and two of these were D. melanogaster and D. simulans, both closely related to D. suzukii; only five G. brasiliensis individuals emerged from the other non-target D. persimilis
This study showed clear differences in the physiological host ranges of A. japonica, G. brasiliensis and L. japonica populations collected from South Korea

Summary

Introduction

Classical biological control is a useful strategy for invasive pest species when effective natural enemies are lacking in the invaded range (Hajek et al 2016; Van Driesche et al 2010). Assessing a natural enemies’ host range is a critical step in developing classical biological control programs (Hoddle et al 2020), as insect parasitoid species may attack phylogenetically related hosts that share physiological traits or ecological niches (Desneux et al 2012). The host range of three solitary endoparasitoids, Asobara japonica Belokobylskij (Hym.: Braconidae), Leptopilina japonica Novković & Kimura and Ganaspis brasiliensis (Ihering) (both Hym.: Figitidae), were evaluated as a part of a North American classical biological control program for the invasive Drosophila suzukii Matsumura (Dip.: Drosophilidae) (Daane et al 2016; Giorgini et al 2019). Improved suppression by natural enemies could reduce fly populations in reservoir habitats before adult flies move into crop habitats, thereby reducing pest pressure (Lee et al 2019)

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