Behavioral responses of parasitoid Trichogramma chilonis towards infochemicals from host plant Solanum melongena and pest Leucinodes orbonalis
Kanuparthi Prasanna Laxmi, Pathipati Usha Rani
Brinjal shoot and fruit borer Leucinodes orbonalis G. is one of the many hosts of Trichogramma chilonis, a generalist egg parasitoid of several crop pests. We studied the effects of different induced contact infochemicals from this pest infested host plant, Solanum melongena L. (Brinjal) and the short-range pest derived kairomones such as larvae frass, female and adult body washings, synthetic pheromone blend and egg surface chemicals on host searching, host acceptance behavior and oviposition behavior of T. chilonis under laboratory conditions. T. chilonis orientation behavior was recorded in Y- olfactometers and oviposition behavior in Petri plates. The crude leaf surface extracts from pest infested Brinjals showed good attractant activity and when various semi-purified ethyl acetate- hexane eluted chromatographic fractions of infested and infected leaf surface extracts were tested, 4%EA-He fraction from infested Brinjal leaf extract exhibited maximum orientation and parasitization followed by 8% EA-He fraction. These results correlated with experiments done using the artificial plants in larger arena. Synthetic pheromone blend as well as female adult body washings arrested the parasitoids and also stimulated parasitization in the dual choice and multi choice oviposition assays. As synthetic pheromone caused highest oviposition rate it is tested in a single armed long tube olfactometer to measure the effective distance of attractant activity. These results are interesting in the context of tritrophic interactions and can find application in biological control.