Copitarsia decolora Guenée (Lepidoptera: Noctuidae) females avoid larvae competition by detecting larvae damaged plants.

Herbivory insects can discriminate the quality of a host plant for food or oviposition, by detecting the volatile organic compounds (VOC's) released by the plant, however, damaged plants may release a different VOC's profile modifying the insects' response. We tested if the VOC's profile from damaged plants affected the response of Copitarsia decolora as these moths oviposit preferably around undamaged host plants. We assessed the response in wind tunnel conditions of C. decolora mated females to volatiles collected by dynamic headspace from 30-40 d old cabbage undamaged plants and mechanical and larval damaged plants. Headspace volatile compounds from undamaged cabbage plants were more attractive to mated females than those from larval and mechanical damaged cabbage plants. Moths stimulated with headspace volatiles from undamaged plants performed more complete flight and ovipositor displays than those moths stimulated with headspace volatiles from damaged cabbage plants. A mixture of synthetic compounds identified from undamaged cabbages elicited similar antennal and wind tunnel responses in mated females as headspace volatiles from undamaged cabbage plants. C. decolora females may discriminate between damaged and undamaged host plants by detecting their VOC's profiles as a strategy to avoid unsuitable plants for their offspring increasing their fitness.