Influence of prey host plant on a generalist aphidophagous predator: Episyrphus balteatus (Diptera: Syrphidae)

The influence of the prey's host plant on both development and reproduction of an aphidophagous beneficial, the hoverfly Episyrphus balteatus, was determined using the cabbage aphid, Brevicoryne brassicae (a specialist) and the peach aphid Myzus persicae (a generalist) reared on Brassica napus and Sinapis alba containing low and high concentrations of glucosinolates (GLS), respectively. The prey and its host plant differently influenced life history parameters of E. balteatus. The predator's rates of development and survival did not vary when it fed on the generalist aphid reared on different host plants. These rates decreased, however, when the predator fed on the specialist aphid reared on the host plant with high GLS concentration versus the host plant with lower GLS concentration. This aphid host plant combination also negatively affected hoverfly reproduction; lower fecundity was observed. As a result, the fitness of the hoverfly was strongly affected. This study illustrates the importance of tritrophic relations in pest management involving predators. The host plant of the prey may have a major influence on the potential of a biological agent to control herbivore species such as aphids.