Volatiles initiate egg-laying in common green lacewings

Abstract: Adults and larvae of the common green lacewing Chrysoperla carnea feed on many insect pest species and are important predators in biological control of many crop plants. Previous work has shown that adults are attracted to chemicals occurring in the scent of flowers, and that the presence of aphids on crop plants enhances oviposition by adults. In the present study, the effect of a three compound blend of phenylacetaldehyd, acetic acid and methyl salicylate was tested for its effect on oviposition by C. carnea in two areas in Norway. In both 2007 and 2008 a significantly higher number of C. carnea eggs were laid inside delta traps with the ternary blend compared to control traps. From 16 May to 15 June 2007 a total of 110 and 177 eggs were found inside 5 baited delta traps in each of two orchards in Western Norway. No eggs were found in control traps. Similar results were obtained in one orchard in Eastern Norway. When lures with the ternary blend were attached directly to the tree, the number of eggs did not significantly increase. Use of attractive volatiles to enhance egg laying, and to increase biological control by lacewings are discussed.