Aspects of the biology and developmental strategy of two Asian larval parasitoids evaluated for classical biological control of Drosophila suzukii

Authors: WANG, XINGENG - University Of California; NANCE, ALEXANDRA - University Of California; JONES, JOHN M.L. - University Of California; Hoelmer, Kim; DAANE, KENT - University Of California

Submitted to: Biological Control
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/9/2018
Publication Date: 10/2/2018
Citation: Wang, X., Nance, A., Jones, J., Hoelmer, K.A., Daane, K. 2018. Aspects of the biology and developmental strategy of two Asian larval parasitoids evaluated for classical biological control of Drosophila suzukii. Biological Control. 121:58-65. https://10.1016/j.biocontrol.2018.02.010.
DOI: https://doi.org/10.1016/j.biocontrol.2018.02.010

Interpretive Summary: The spotted wing drosophila fly is native to eastern Asia but has also become established in Europe and in North and South America, where it has become the most serious pest of berries and other small fruits. Two parasitic wasps that are natural enemies of the fly in Asia were imported from South Korea for evaluation as potential biological control agents in the USA. In a quarantine laboratory we studied aspects of their biology that are important for them to be effective agents. Young female wasps emerge from their host fly bodies ready to search for and attack new flies. The two wasp species have similar biologies: they prefer to attack young fly larvae, and they have a life span of about two and a half weeks, during which a parent female wasp is capable of producing about a hundred offspring. This biological information will help to determine their value as potential biological control agents.

Technical Abstract: Drosophila suzukii Matsumura (Diptera: Drosophilidae) is native to eastern Asia, but has established in Europe and in both North and South America, where it is a pest of numerous fruit crops. As part of a classical biological control program, two larval D. suzukii parasitoids, Ganaspis brasiliensis Ihering and Leptopilina japonica Novkovic & Kimura (Hymenoptera: Figitidae), were imported from South Korea to a California quarantine for evaluation. Here, we report on aspects of their reproductive strategy, including egg maturation dynamics, host stage preference and suitability, and life-time fecundity. Adult females of both species emerged with a high mature egg-load that peaked 1–2 days post emergence. Both parasitoid species preferred to attack young host larvae (1–2 days old), although host age did not affect the parasitoid offspring’s sex ratio or fitness (survival, developmental time and body size of female wasps). Held at 22 degrees C with honey-water and D. suzukii larvae, G. brasiliensis adult females survived ca. 17.7 days and produced 98.3 offspring, while L. japonica survived 18.7 days and produced 107.2 offspring. The proportion of female progeny decreased with increasing maternal age for both parasitoid species. Estimated demographic parameters were similar for both G. brasiliensis and L. japonica: net reproduction rate was 39.9 and 47.3, intrinsic rate of increase was 0.130 and 0.138, mean generation time was 28.5 and 28.1 days, and doubling time was 5.4 and 5.0 days, respectively. This information is being used to compare exotic D. suzukii parasitoids and determine their value as potential biological control agents.