Selective flowers to attract and enhanceTelenomus laeviceps(Hymenoptera: Scelionidae): a released biocontrol agent ofMamestra brassicae(Lepidoptera: Noctuidae)

Abstract

AbstractThe importance of the right food source for the survival and reproduction of certain insect species is well documented. In the case of biocontrol agents, this is even more important in order to reach a high predation or parasitation performance. The egg parasitoidTelenomus laeviceps(Förster, 1861) (Hymenoptera: Scelionidae) is a promising candidate for mass release as a biological control agent of the cabbage mothMamestra brassicae(Linnaeus, 1758) (Lepidoptera: Noctuidae). However, adultT. laevicepsneed a sugar-rich food source to increase their parasitation performance and produce a good amount of female offspring. Released biocontrol agents were shown to benefit from conservation biocontrol, which includes the provision of selected flowers as nectar resources for beneficial insects. In Switzerland,Centaurea cyanusL. (Asteraceae),Fagopyrum esculentumMoench (Polygonaceae) andVicia sativaL. (Fabaceae) are successfully implemented in the field to attract and promote natural enemies of different cabbage pests. In this study, we investigated the potential of these selected flowers to attract and promoteT. laevicepsunder laboratory conditions. In Y-tube olfactometer experiments, we first tested whether the three nectar providing plant species are attractive toT. laeviceps. Furthermore, we assessed their effects on survival and parasitation performance of adultT. laeviceps. We found that flowers ofF. esculentumandC. cyanuswere attractive in contrast toV. sativa.Also fecundity and the number of female offspring produced were higher for females kept onF. esculentumandC. cyanusthan onV. sativa.In contrast, survival was similar on all treatments. Our findings present a further key step towards the implementation ofT. laevicepsas a biocontrol agent.