Classical biological control of Drosophila suzukii with Asian parasitoids

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1 Photo: T. Haye Classical biological control of Drosophila suzukii with Asian parasitoids Marc Kenis and DROPSA partners KNOWLEDGE FOR LIFE

2 Drosophila suzukii: Characteristics +100 host species (wild, ornamental and crop fruits) High fecundity Many generations per year Need for an area-wide control strategy Photo: M. Kenis Photo: UNIPD

3 Drosophila suzukii: Characteristics +100 host species (wild, ornamental and crop fruits) High fecundity Many generations per year Need for an area-wide control strategy Natural enemies: Photo: T. Haye Photo: T. Colin Photo: Fera Photo: Fera

4 Few natural enemies in invasion range Some generalist pupal parasitoids and predators Photo: T. Colin Photo: MyrmecoFourmis.fr But they tend to search only in the soil

5 Few natural enemies in invasion range Larval parasitoids of Drosophila spp. either do not show interest in D. suzukii Or attack but eggs are encapsulated: D. suzuki has a very high heamocyte load that allows it to resist to the immunosuppressive properties of parasitoids Photos: T. Haye & P. Girod

6 Biological control Native natural enemies as biocontrol products on the market E.g. pupal parasitoid Trichopria drosophilae available in some countries Photo: T. Colin

7 Fraimout et al. (2017) Molecular Biology and Evolution 34: Classical biological control Intentional introduction of an exotic, usually co-evolved, biological control agent for permanent establishment and long-term pest control?

8 Classical biological control Importation of larval parasitoids from Asia in Photos: M. Kenis & P. Girod

9 Classical biological control Main results: D. suzukii is less frequent in Asia than in Europe About 19,000 insects were collected at more than 50 sites Fresh fruits contained D. suzukii but also 2 other fruit pests D. pulchrella and D. subpulchrella Larval parasitism rate in Asia varied between % At least eight parasitoid species were obtained

10 Classical biological control Most abundant and frequent parasitoids: Ganaspis sp. Leptopilina japonica Photos: P. Girod

11 Classical biological control Importation and study of parasitoids from Asia in quarantine in CH and F: At least three species and many strains from China and Japan Asobara japonica Leptopilina japonica Ganaspis sp. Photos: M. Kenis & P. Girod

12 Classical biological control Studies presently being carried out in quarantine: 1. Biology E.g. lify cycle, development time, preoviposition period, efficiency, preference for substrate, All parasitoids lay eggs in young larvae and kill the pupae Photo: T. Haye

13 Classical biological control Studies presently being carried out in quarantine: 1. Biology Ganaspis sp. does not like D. suzukii larvae in artificial diet Photos: T. Haye

14 Classical biological control Studies presently being carried out in quarantine: 2. Specificity Tests on many different flies to assess potential non target effects in Europe

15 Classical biological control Studies presently being carried out in quarantine: 2. Specificity Also tests in olfactometers to understand the mechanisms of specificity

16 Classical biological control Studies presently being carried out in quarantine: 2. Specificity: main results so far: Ganaspis sp. is the most specific parasitoids but different biotypes (or cryptic species) do exist with different specificity: -Some biotypes 100% specific: only attack D. suzukii in fruits Photo: T. Haye -Others also attack D. melanogaster and D. suzukii in diet

17 Classical biological control - Conclusions Classical biological control represents one of the few solutions for long term and area-wide control Surveys in Asia showed that D. suzukii is parasitised at variable rates. Parasitism is surely at least partly responsible for the lower occurrence of D. suzukii in Asia. Ganaspis sp. is the most promising candidate for introduction in Europe because it is the most abundant and the most specific parasitoid

18 Classical biological control - Conclusions Additional studies are needed before Ganaspis sp. can be autorised for release in Europe Taxonomic status and existence of cryptic species Additional specificity tests (more fly species to be tested, multiple choice tests, tests on different fruits) Climatic requirements and variations in these requirements, with selection of strains adapted to temperate regions

19 Partners: MoA - CABI (Beijing, China) Yunnan Agricultural University (Kunming, China) INRA (Sophia-Antipolis, France) University of Sapporo (Sapporo, Japan) Agroscope (Switzerland) University of Neuchâtel (Switzerland) Donors: جزیلا kiitos KNOWLEDGE FOR LIFE merci شكرا श क रय xie-xie zikomo efharistó thank you tak ありがとう gracias zikomo danke urakoze ke itumetse terima kasih obrigado dhanyawaad asante