Submitted to: Naturwissenschaften
Publication Type: Peer reviewed journal
Publication Acceptance Date: 5/18/2006
Publication Date: 9/1/2006
Citation: Zhang, Q., Sheng, M., Chen, G., Aldrich, J.R., Chauhan, K.R. 2006. Iridodial: a powerful attractant for the green lacewing, chrysopa septempunctata (neuroptera: chrysopidae). Naturwissenschaften. 93: 461-465. Interpretive Summary: Biological control of insect pests is a desirable alternative to insecticidal control. We demonstrated that an important and abundant predator of aphids in Asia and Europe (one of the so-called lacewings named Chrysopa septempunctata) is attracted to the same chemical earlier found attractive to these kinds of lacewings in North America. Thus, a single chemical (that can be simply derived from the commercially available catnip plant) can be used to attract various kinds of lacewings throughout the northern hemisphere to naturally suppress aphids and other pests. These findings will be of practical utility to gardeners and commercial growers alike who will now be able to naturally induce female lacewings to lay eggs among pest infestations for enhanced biological control. Scientists studying chemicals affecting predator behavior will also be interested in these results. A new attractant system for green lacewings is being developed at Sterling International, Inc. for both domestic and international markets.
Technical Abstract: Chrysopa septempunctata Wesmael is one of the most common and economically important beneficial insects in China, Japan, Russia and many parts of Europe. Our field trapping experiments in Northeast China showed that males of this green lacewing are strongly attracted to the newly discovered lacewing pheromone of C. oculata Say, (1R,2S,5R,8R)-iridodial. Methyl salicylate, reportedly a field attractant for two Chrysopa species in the United States, was unattractive to C. septempunctata by itself at the concentration tested, but showed a synergistic effect when combined with iridodial at one site where the lacewing population was high, and had no effect at the other site where lacewings were less abundant. Z,E-Nepetalactol and Z,E-nepetalactone are major sex pheromone components for many aphids, and were found to be attractive to several Chrysopa spp. Traps baited with Z,E-nepetalactol or Z,E-Nepetalactone caught significantly more males of C. septempunctata than did blank control traps, with the former being more attractive than the latter. Iridodial out-competed both Z,E-nepetalactol and Z,E-nepetalactone in the field, and remained strongly attractive to C. septempunctata males for at least 2.5 months during the summer when loaded in the polyethylene bag dispensers. Our results, along with the recent discovery of the C. oculata pheromone, challenge an earlier hypothesis that these lacewings use aphid sex pheromones as host-finding kairomones. Instead, we suggest that the attraction or positive responses to these aphid sex pheromone components by lacewings might be due to their structural similarity to the lacewing pheromone, iridodial.