Potential host ranges of three Asian larval parasitoids of Drosophila suzukii

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.

Large-arena field cage releases of a candidate classical biological control agent for spotted wing drosophila suggest low risk to non-target species

“…Only a single parasitoid emerged from D. melanogaster. This confirms our hypothesis and supports the results of previous laboratory choice and no-choice experiments performed in relatively small containers (Giorgini et al 2019;Girod et al 2018b;Biondi et al 2021;Seehausen et al 2020;Daane et al 2021).…”

“…The risk of released parasitoids to also occasionally attack and kill native Drosophila species cannot be excluded, especially those that can be found in rotten or even injured fruits, such as D. melanogaster and D. simulans. But given the results of laboratory experiments (Giorgini et al 2019;Girod et al 2018b;Biondi et al 2021;Seehausen et al 2020;Daane et al 2021) and our field cage releases, parasitism of non-target species can be expected to be negligible and unlikely to have any significant ecological impact.…”

The roles of phenotypic plasticity and adaptation in morphology and performance of an invasive species in a novel environment

“…Research on potential biological control agents for D . suzukii illustrates that the introduced range is depauperate in natural enemies (Daane et al ., 2016, 2021; Kamiyama et al ., 2019), supporting the idea that populations on Hawaii might thrive due to enemy release rather than adaptation to their environment.…”

First records of adventive populations of the parasitoids Ganaspis brasiliensis and Leptopilina japonica in the United States

“…To determine the suitability of these parasitoids for classical biological control, studies of their biology and host range were conducted in quarantine facilities in Switzerland (Girod et al 2018b, c) and California (Wang et al 2018;Hougardy et al 2019;Wang et al 2019Wang et al , 2020Biondi et al 2021). Some populations of G. brasiliensis appear to be more specialized on D. suzukii, whereas other populations have broader host ranges (Girod et al 2018b;Seehausen et al 2020;Daane et al 2021). Nomano et al (2017) grouped G. brasiliensis into five "lineages" (G1-G5), hereafter referred to as "groups", based on molecular analyses and suggested that G1 material collected in Japan was host specific to D. suzukii.…”