Field Monitoring of Drosophila suzukii and Associated Communities in South Eastern France as a Pre-Requisite for Classical Biological Control

Abstract

The spotted wing Drosophila, Drosophila suzukii (Ds), became a major economic pest for fruit production since its establishment in Europe and America. Among potential control methods, only classical biological control appears to be a mean of sustainably regulating Ds in both cultivated and natural habitats. In the frame of risk assessment, pre-release surveys were carried out in a restricted but highly heterogeneous area in the south-east of France using traps and deliberate field exposures of Ds and D. melanogaster larvae/pupae. Although Ds abundance varied according to sampling methods, it was found to be pervasive and to produce offspring and adults in most conditions (spatial and seasonal). Its main limits are some specific abiotic conditions (i.e., desiccation) as well as interspecific competition. Indeed, Ds mostly co-occurred with D. busckii and D. hydei, probably due to common phenology and/or ecological requirements. These two species thus deserve more attention for risk assessment. The main indigenous parasitoids collected belonged to two pupal species, Trichopria cf drosophilae and Pachycrepoideus vindemmiae, but their presence was observed late in the autumn and mainly in cultivated areas. Results are discussed in a comparison of the methodological approaches for monitoring Drosophilids and the benefits-risks assessment of classical biological control.

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

“…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 .…”

Multiscale Determinants Drive Parasitization of Drosophilidae by Hymenopteran Parasitoids in Agricultural Landscapes

“…Since larval and pupal parasitoids exhibit various degrees of polyphagy, their association with drosophilid species may be deeply driven by the interaction of multiple biotic and abiotic factors acting at different spatial scales. Kremmer et al [31] pointed out that some native species of drosophilids showed similar ecological preferences to D. suzukii and thus could be affected as non-target species in biological control programs because they could be included in the range of hosts from the suite of natural enemies. A recent study focusing on D. suzukii showed a positive relationship between forest cover and landscape complexity within a 1.5 km radius and the presence and abundance of parasitoids [24], yet only a minor proportion of those parasitoids belonged to species that parasitize Drosophila.…”

“…Numerous indigenous parasitoids attacking the larvae and pupae of various species of Drosophilidae are found worldwide, most of them are generalist to a certain extent, while no parasitoids of eggs or adults are known [ 26 ]. When D. suzukii became established in Europe and North America, several studies characterized indigenous parasitoids that could potentially include D. suzukii in their host spectrum [ 27 , 28 , 29 , 30 , 31 ]. In Europe, hymenopteran larval parasitoids, Asobara tabida (Nees, 1834) (Braconidae), Leptopilina boulardi (Barbotin, Carton and Kelner-Pillault, 1979) and L. heterotoma (Thomson, 1862) (Figitidae), did either not parasitize D. suzukii or their eggs were encapsulated by the host [ 32 ]; however, egg laying by the latter two still reduced the fitness of D. suzukii [ 30 , 33 ].…”

Influence of the Rearing Host on Biological Parameters of Trichopria drosophilae, a Potential Biological Control Agent of Drosophila suzukii

“…In particular, parasitoid wasps, and among those, the pupal parasitoid Trichopria drosophilae (Perkins; Hymenoptera: Diapriidae), have received much attention as potential biological control agents for D. suzukii [23,24,25,26,27]. The species has been recorded in Asia (Korea: [28] China: [27]), America (California: [23], Mexico: [29]), and Europe (Spain: [19], Italy: [30], Switzerland [31], France [32]). Parasitization rates of D. suzukii by T. drosophila are high under laboratory conditions [32,33], and rearing in large numbers is feasible.…”