Effect of alternative nectar sources and herbivore-induced plant volatiles on the fitness and attraction of Aphidoletes aphidimyz

Abstract

Enhancing natural enemy populations in agricultural systems by combining habitat manipulation and herbivore-induced plant volatiles (HIPVs) offers a promising approach to conservation biological control. The aphidophagous midge Aphidoletes aphidimyza is widely used in biological control programs in many crops, and the development of novel attract and reward (A&R) strategy may promote the establishment and survival of A. aphidimyza in crops. Here, we focus on (i) the attractiveness (under laboratory conditions) to A. aphidimyza of the HIPVs phenylacetaldehyde (Pal) and methyl salicylate (MeSA) and plants in the families Brassicaceae, Euphorbiaceae, Asteraceae and Fabaceae, all evaluated separately, and (ii) the effect of consuming nectar from Eruca vesicaria, Euphorbia segetalis, Moricandia arvensis, Calendula officinalis, Vicia faba, V. sativa, Medicago sativa, and Centaurea cyanus on A. aphidimyza survival, as well as the impact of the first five species on egg load. Neither of the tested HIPVs (Pal and MeSA) induced a positive chemotactic response in double-choice bioassays, nor did any of the tested plants. Survival curves varied according to the food provided; A. aphidimyza females fed V. faba, V. sativa (Fabaceae), or E. vesicaria (Brassicaceae) had the highest survival rates, significantly higher than those of A. aphidimyza fed only water. Plant food sources also impacted egg load, which was significantly higher in females fed C. officinalis than in those fed V. faba; egg numbers in females fed E. vesicaria did not differ significantly from either. Together, these findings represent a first step toward determining the potential of insectary plants for improving A. aphidimyza performance.