Influence of plant species on biological control effectiveness of Myzus persicae by Aphidius gifuensis

Abstract

Most insect herbivores can attack a wide range of plant species, which directly affect their performance and abundance. Plant species may also affect parasitoid performance by influencing their host location and host suitability, and further affect their pest control effectiveness. Here we tested the effects of three plant species, sweet pepper (Capsicum annuum), cabbage (Brassica oleracea), and crown daisy (Glebionis coronaria), on the performance of a general insect pest, the aphid Myzus persicae and its parasitoid Aphidius gifuensis; and we also compared the control effectiveness of M. persicae by A. gifuensis among these three plant species. Plant species affected the performance of both M. persicae and A. gifuensis, as well as the aphid suppression by the parasitoid. Both M. persicae and A. gifuensis performed best on sweet pepper and worst on cabbage. The aphid nymphs developed fastest on sweet pepper and slowest on cabbage. The sweet pepper-fed aphids had the highest body weight and nymphal survival rate; cabbage-fed aphids had the lowest body weight and nymphal survival rate. In both choice and no-choice tests, A. gifuensis produced most offspring and their offspring were most female-biased on sweet pepper. In addition, the parasitoids reared on sweet pepper-fed aphids were largest among the three populations reared on the three plant species. In olfactory response tests, female A. gifuensis showed a stronger response to both undamaged sweet pepper and crown daisy seedlings and plant-aphid complexes compared to clean air, and the plant-aphid complexes were more attractive than healthy plants. The percentage reduction of cumulative aphid-days on sweet pepper was significantly higher than that on the other two plant species. Our results suggested that the impact of plant species on herbivore diffuses up the food chain, and plant species can affect biological control effectiveness of parasitoids.