Development of Asian parasitoids in larvae Of Drosophila Suzukii feeding on blueberry and artificial diet

Abstract

In just a few years, the Asian fly Drosophila suzukii has invaded several continents and has become a very serious pest of many fruit crops worldwide. Current control methods rely on chemical insecticides or expensive and labour-intensive cultural practices. Classical biological control through the introduction of Asian parasitoids that have co-evolved with the pest may provide a sustainable solution on condition that they are sufficiently specific to avoid non-target effects on local biodiversity. Here, we present the first study on the development of three larval parasitoids from China and Japan, the Braconidae Asobara japonica and the Figitidae Leptopilina japonica and Ganaspis sp., on D. suzukii. The Asian parasitoids were compared with Leptopilina heterotoma, a common parasitoid of several Drosophilidae worldwide. The three Asian species were successfully reared on D. suzukii larvae in both, blueberry and artificial diet, in contrast to L. heterotoma whose eggs and larvae were encapsulated by the host larvae. All parasitoids were able to oviposit one day after emergence.Asobara japonica laid as many eggs in larvae feeding in blueberry as in artificial diet, whereas L. heterotoma oviposited more in larvae on the artificial diet and the Asian Figitidae oviposited more in larvae feeding on blueberry. Ganaspis sp. laid very few eggs in larvae in the artificial diet, suggesting that it may be specialized in Drosophila species living in fresh fruits. These data will be used for the development of a host range testing to assess the suitability of Asian parasitoids as biological control agents in invaded regions. K E Y W O R D SAsobara, Ganaspis, invasive species, Leptopilina, pre-oviposition period, spotted wing drosophila short development time of the fly, they have to be applied regularly and can cause severe environmental and health concerns (Bruck et al., 2011;Cuthbertson, Collins, Blackburn, Audsley, & Bell, 2014;Sampson, Werle, Stringer, & Adamczyk, 2017;Smirle, Zurowski, Ayyanath, Scott, & MacKenzie, 2017;Van Timmeren & Isaacs, 2013).Cultural management such as the use of insect-proof nets, mass trapping and removal or solarization of infested fruits are also used, but these strategies are expensive and labour-intensive and have to be adjusted to each type of fruit crop or cultivation system (Haye et al., 2016). New control techniques focusing on long-term management are therefore urgently needed. As wild host plants constitute a large reservoir of individuals that can potentially reinvade field crops, controlling the pest at a landscape level is essential.A number of natural enemies are known to have an impact on the dynamics and regulation of Drosophila spp. and may provide an area-wide control of fly populations (Carton, Bouletreau, Lenteren, & Alphen, 1986;Fleury, Gibert, Ris, & Allemand, 2009).Two generalist pupal parasitoids, Trichopria drosophilae Perkins (Hymenoptera, Diapriidae) and Pachycrepoideus vindemmiae (Rondani) (Hymenoptera, Pteromalidae), are found attacking D. suzukii worldwide ...

Time-course analysis of Drosophila suzukii interaction with endoparasitoid wasps evidences a delayed encapsulation response compared to D. melanogaster

“…Previous investigations on D . suzukii— parasitoids interactions were obtained mainly by quantifying the final outcome (numbers of emerged non-parasitized adult flies, adult flies with capsules or parasitoids [ 23 – 25 , 27 – 29 ]), without monitoring in details the physiological interactions. Here, we sought to better understand the success or failure of parasitism of sympatric and allopatric endoparasitoid wasps on the larval stages of D .…”

“…heterotoma kills about 40% of D . suzukii larvae and is successful at a low rate in laboratory, which probably accounts for the undetected emergence of this parasitoid from field exposed larvae or sampled pupae in fruits [ 19 , 25 , 64 , 65 ]. In semi-natural conditions, we observed that L .…”

Host specificity of Asian parasitoids for potential classical biological control of Drosophila suzukii

“…In experiment A, A. japonica, L. japonica and L. heterotoma were tested on D. suzukii , D. melanogaster , D. immigrans , D. subobscura and D. busckii in plain regular CAROLINA© diet instead of fruit (Table 1, Experiment A), because Girod et al (2018a) demonstrated that these species would show the same parasitism behaviour with larvae in this artificial diet and blueberries. In experiment B, the two populations of Ganaspis cf.…”

“…is not accepted as substrate by Ganaspis cf. brasiliensis (Girod et al 2018a ). However, besides D. suzukii, none of the Drosophila species used in this study lays eggs in fresh fruits.…”

Context-Dependence and the Development of Push-Pull Approaches for Integrated Management of Drosophila suzukii

“…The parasitoids Asobara japonica, Leptopilina japonica, and Ganaspis cf. brasiliensis may be good candidates [142][143][144]. For this option, however, various regulations need to be met with, including the Nagoya protocol and phytosanitary regulations for import and release of biocontrol agents to avoid unwanted effects on non-target organisms [145][146][147].…”