Trichopria anastrephae as a biological control agent of Drosophila suzukii in strawberries

Abstract In South America, the resident pupal parasitoid Trichopria anastrephae Costa Lima (Hymenoptera: Diapriidae) is a potential biological control agent of the pest Drosophila suzukii Matsumura (Diptera: Drosophilidae). In the present study we 1) examined the behavior of T. anastrephae towards different host (D. suzukii) and host-substrate (strawberry) cues in choice and non-choice bioassays in laboratory, and 2) examined the density-dependent parasitism of T. anastrephae in D. suzukii-infested strawberries in a greenhouse. We tested infested and non-infested strawberries for the behavioral assays in a four-chamber olfactometer. For the greenhouse bioassay, we set five walk-in cages with strawberry plants in a greenhouse, released D. suzukii adults, and then released different numbers of parasitoids (0, 60, 120, 240, and 360) in each cage. In non-choice bioassays, female parasitoids showed a preference towards D. suzukii-infested strawberries containing larvae, pupae or inoculated pupae, or healthy overripe fruits. When given a choice, female parasitoids walked longer over chambers with fruits infested with eggs, larvae, or pupae of D. suzukii, when compared to healthy uninfested strawberries, and over overripe fruits when compared to unripe or ripe fruits. In the greenhouse assay, we observed an increase in parasitism and a decrease in the number of D. suzukii emerging per fruit with an increase in the number of parasitoids released. Our results allow a better understanding of the behavior and parasitism of T. anastrephae in D. suzukii-infested strawberries and provide useful data for potential biological control programs using this parasitoid.