Behavioral responses of Chrysoperla externa (Neuroptera: Chrysopidae) in a rose–aphid–coriander complex interaction

Natural enemy behavior is mediated by cues associated with the host-plant complex, such as volatiles emitted by damaged plants, and the surrounding vegetation.  In this study, we investigated: a) under greenhouse conditions, green lacewing, Chrysoperla externa, adult attraction and oviposition on rose, Rosa sp., damaged by the potato aphid, Macrosiphum euphorbiae, and on undamaged plants, and whether this interaction is affected by the presence of coriander, Coriandrum sativum (a potential companion plant); b) in the laboratory, the role of volatiles on female C. externa attraction to undamaged and aphid-damaged rose, coriander, and from the rose-coriander complex; and, c) aphid induction of volatiles from rose plants.  In the greenhouse, numbers of C. externa adults were higher on aphid-damaged roses and on roses near coriander plants; however, there was no aphid × coriander interaction, indicating that attraction to aphid-damaged 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-damaged rose, coriander only, and the rose-coriander complex and were repelled by rose volatiles; however, there was no difference in C. externa attraction between aphid-damaged rose versus aphid-damaged rose plus coriander.  Headspace analysis revealed that aphid-damaged rose emits higher quantities of methyl salicylate compared with undamaged rose.  In conclusion, although C. externa adults were attracted to coriander, coriander did not increase attraction or oviposition of this predator to aphid-damaged roses.