Behavioral responses of adult lacewings, Chrysoperla externa, to a rose–aphid–coriander complex

Abstract

Natural enemy behavior is mediated by cues associated with the host-plant complex, such as volatiles emitted by damaged plants and the surrounding vegetation. We conducted studies to investigate whether: (a) adult attraction of green lacewing, Chrysoperla externa Hagen, to and oviposition on rose, Rosa×hybrida L., infested by the potato aphid, Macrosiphum euphorbiae Thomas, is affected by the presence of coriander, Coriandrum sativum L. (a potential companion plant); (b) the role of volatiles on female C. externa attraction to uninfested and aphid-infested rose, coriander, and from the rose–coriander complex; and, (c) whether M. euphorbiae feeding induces volatile emissions from rose plants. In the greenhouse, numbers of C. externa adults were higher on aphid-infested rose and on roses near coriander plants; however, there was no aphid×coriander interaction, indicating that attraction to aphid-infested rose was not influenced by the presence of coriander. Aphids increased the number of eggs laid by C. externa on rose but this was also not affected by the presence of coriander. In Y-tube studies, C. externa females showed attraction to volatiles from aphid-infested rose, coriander only, and the rose–coriander complex and were not attracted to rose volatiles; however, there was no difference in C. externa attraction between aphid-infested rose versus aphid-infested rose plus coriander. Headspace analysis revealed that aphid-infested rose emits greater quantities of methyl salicylate compared with uninfested rose. In conclusion, although C. externa adults were attracted to coriander, coriander did not increase attraction or oviposition of this predator to aphid-infested rose.