Honeydew as a food source for natural enemies: Making the best of a bad meal?

Abstract

The majority of predators and parasitoids require non-prey food as part of their diet. The availability of suitable non-prey food can impact predator–prey and parasitoid–host dynamics and may be critical to the efficacy of biological pest control. A growing body of work addresses the role of floral nectar in conservation biological control programs. In comparison, we know relatively little about the role of honeydew as a sugar source for predators and parasitoids, in spite of the fact that honeydew is often the predominant sugar source in agroecosystems. Here we test the hypothesis that honeydew is a less suitable food source when compared with other sugar sources, using data from parasitoid literature. We also explore whether parasitoids of honeydew-producing insects show particular adaptations allowing them to optimize the exploitation of this suboptimal food source. A review of available literature supports the general hypothesis that honeydew is inferior to other sugar sources, although there is considerable variation in the quality of honey