Host stage preference, efficacy and fecundity of parasitoids attacking Drosophila suzukii in newly invaded areas

• Populations of two parasitoids of Drosophila suzukii were tested under laboratory conditions.
• Only the Italian population of Leptopilina heterotoma parasitized D. suzukii.
• Italian and North American populations of Pachycrepoideus vindemiae parasitized D. suzukii.
• Host pupal preference and lifetime fecundity of P. vindemiae were determined.
• A third parasitoid species, Trichopria drosophilae, showed the ability to parasitize D. suzukii.

Drosophila suzukii (Matsumura) (Diptera: Drosophilidae) causes severe damage to certain fruit crops in both North America and Europe. This may be due, in part, to the absence of specialized natural enemies that suppress population outbreaks. We performed a series of experiments under controlled laboratory conditions in tandem with a field study to evaluate the presence and efficacy of natural enemies associated with this pest in Italian and western United States fruit production regions. Our study involved one larval parasitoid, Leptopilina heterotoma (Thomson) (Hymenoptera: Figitidae), and two pupal parasitoids, Pachycrepoideus vindemiae (Rondani) (Hymenoptera: Pteromalidae) and Trichopria drosophilae (Perkins) (Hymenoptera: Diapriidae). Three indices were used to describe host-parasitoid interactions: degree of infestation (DI), success rate of parasitism (SP) and total encapsulation rate (TER). Results confirmed that each of these parasitoid species can develop on certain populations of the pest. In addition, host stage preferences of the tested parasitoid populations, developmental parameters and lifetime fecundity of North American P. vindemiae are provided. Results are discussed with respect to differences in potential utilization of D. suzukii among the tested parasitoid species and regional populations.

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