Effects of temperature and food source on reproduction and longevity of aphid hyperparasitoids of the genera Dendrocerus and Asaphes

Abstract

Hyperparasitoids of aphid parasitoids commonly occur in (sweet pepper) greenhouses, and can pose a threat to effective biological control of aphids. Here, we studied life history characteristics of laboratory colonies of Dendrocerus spp. Ratzeburg (Hymenoptera: Megaspilidae) and Asaphes spp. Walker (Pteromalidae) that originated from a commercial sweet pepper greenhouse. We aimed to clarify how these two hyperparasitoid taxa can coexist inside greenhouses. Hyperparasitoids of both taxa have a long lifespan that was extended significantly by food sources that are naturally available in a greenhouse environment, including aphid honeydew and sweet pepper flowers. Differences in sensitivity to decreased or increased temperatures did not appear to explain seasonal patterns in abundance of Dendrocerus spp. and Asaphes spp. in sweet pepper greenhouses. Instead, Dendrocerus spp. may have an advantage early in the season because it thrives on aphid honeydew, while Asaphes spp. may do better later in the season because of its long lifespan and extensive reproductive period.