Aphid honeydew enhances parasitoid longevity to the same extent as a high quality floral resource: implications for conservation biological control of the wheat stem sawfly (Hymenoptera: Cephidae)

Authors: Rand, Tatyana; Waters, Debra

Submitted to: Journal of Economic Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/25/2020
Publication Date: 4/25/2020
Citation: Rand, T.A., Waters, D.K. 2020. Aphid honeydew enhances parasitoid longevity to the same extent as a high quality floral resource: implications for conservation biological control of the wheat stem sawfly (Hymenoptera: Cephidae). Journal of Economic Entomology. https://doi.org/10.1093/jee/toaa076.
DOI: https://doi.org/10.1093/jee/toaa076

Interpretive Summary: The absence of sugar resources in highly simplified agricultural landscapes can severely limit the efficacy of biological control agents. Habitat management approaches that put flowers back into these landscapes (e.g. through flower strips or cover cropping) are thus often critical to increasing the efficacy of biological control parasitoids. We screened three flowering cover crop species, and one aphid species, for their potential to increase longevity of the parasitoid wasp, Bracon cephi, an important biological control agent of the wheat stem sawfly, Cephus cinctus. We found that buckwheat and honeydew from aphids that feed in wheat increased parasitoid longevity by over three fold, while longevity on sunflower and coriander was not significantly different from controls. The results suggest that incorporating buckwheat into cover crop mixes could enhance parasitoid performance, but also that more information on the availability and presence of aphid honeydew will be an important consideration when evaluating the potential benefits of flower resources for parasitoid conservation.

Technical Abstract: Providing sugar resources for parasitoids is an important component of habitat management approaches to bolster biological control. We screened three flowering cover crop species, and one aphid species, for their potential to increase longevity of the parasitoid wasp, Bracon cephi, an important biological control agent of the wheat stem sawfly, Cephus cinctus. We found that buckwheat and honeydew from the cereal aphid, Rhopalosiphum padi, increased longevity of B. cephi females by over three fold, while longevity on sunflower and coriander was not significantly different from controls. The results suggest that incorporating buckwheat into cover crop mixes could enhance parasitoid performance. However, the finding that honeydew associated with a common aphid in wheat provides a suitable resource, suggests that a better understanding of the varying quality, and spatial and temporal availability, of aphid honeydew will be an important consideration in evaluating the potential benefits of managing floral resources for parasitoid conservation.