Impact of botanical pesticides derived from Melia azedarach and Azadirachta indica plants on the emission of volatiles that attract parasitoids of the diamondback moth to cabbage plants
Journal of Chemical Ecology
Insect Ecology, Agricultural Research Council, Plant Protection Research Institute, Private Bag X134, Queenswood 0121, South Africa; Laboratory of Entomology, Department of Plant Sciences, Wageningen University, P.O. Box 8031, 6700 EH Wageningen, Netherlands; Netherlands Institute of Ecology, NIOO-CL, P.O. Box 1299, 3600 BG, Maarssen, Netherlands
Herbivorous and carnivorous arthropods use chemical information from plants during foraging. Aqueous leaf extracts from the syringa tree Melia azedarach and commercial formulations from the neem tree Azadirachta indica, Neemix 4.5®, were investigated for their impact on the flight response of two parasitoids, Cotesia plutellae and Diadromus collaris. Cotesia plutellae was attracted only to Plutella xylostella-infested cabbage plants in a wind tunnel after an oviposition experience. Female C. plutellae did not distinguish between P. xylostella-infested cabbage plants treated with neem and control P. xylostella-infested plants. However, females preferred infested cabbage plants that had been treated with syringa extract to control infested plants. Syringa extract on filter paper did not attract C. plutellae. This suggests that an interaction between the plant and the syringa extract enhances parasitoid attraction. Diadromus collaris was not attracted to cabbage plants in a wind tunnel and did not distinguish between caterpillar-damaged and undamaged cabbage plants. Headspace analysis revealed 49 compounds in both control cabbage plants and cabbage plants that had been treated with the syringa extract. Among these are alcohols, aldehydes, ketones, esters, terpenoids, sulfides, and an isothiocyanate. Cabbage plants that had been treated with the syringa extract emitted larger quantities of volatiles, and these increased quantities were not derived from the syringa extract. Therefore, the syringa extract seemed to induce the emission of cabbage volatiles. To our knowledge, this is the first example of a plant extract inducing the emission of plant volatiles in another plant. This interesting phenomenon likely explains the preference of C. plutellae parasitoids for cabbage plants that have been treated with syringa extracts. © 2006 Springer Science + Business Media, Inc.
acylglycerol; insecticide; neem oil; plant extract; terpene; host-parasite interaction; pesticide; plant; animal; article; Azadirachta indica; Brassica; chemistry; drug effect; feeding behavior; female; host parasite interaction; Hymenoptera; insect control; larva; Melia azedarach; metabolism; moth; parasitology; physiology; Animals; Azadirachta; Brassica; Feeding Behavior; Female; Glycerides; Host-Parasite Relations; Hymenoptera; Insect Control; Insecticides; Larva; Melia azedarach; Moths; Plant Extracts; Terpenes; Arthropoda; Azadirachta indica; Brassica oleracea var. capitata; Cotesia plutellae; Diadromus collaris; Lepidoptera; Melia azedarach; Plutella xylostella; Syringa