INFLUENCE OF DIFFERENT ODOURS ON THE ASSOCIATIVE LEARNING OF LARVAL PARASITOID COTESIA PLUTELLAE (K.) (HYMENTOPTERA: BRACONIDAE)

Abstract

The ability of insect parasitoids to learn a wide range of volatiles enables them to exploit the habitats while still maintaining their searching efficiency and achieving efficient rates of oviposition. In the present study, learning of Cotesia plutellae adults on various inexperienced odours and their memory dynamics has been studied. The odours either repelled or acted as neutral stimulus under unexperienced condition. However, they were found to be equally efficient to associate the novel odour viz. coriander, rose, vanilla, and citral with food source in an olfactometer. After experiencing the wasps with different odours, the memory of rose and coriander odour remained for more than four hours but the memory faded on vanilla and citral within four hours. It was also found that the
learning in these wasps depended on the duration of exposure to the odour while feeding on food source. The C. plutellae females could learn two odours at a time and responded to both odours in olfactometer when provided individually. Females did not show any preference for learned odour of vanilla and citral when both were provided in two choice condition in the olfactometer. But female preferred the rose odour over vanilla in the olfactometer after experiencing both the odour. This finding can be utilized to design the innundative release of the parasitoids. Growing coriander or rose flower in the vicinity of field and experiencing the wasps to these odours before releasing into field can arrest these parasitoids in the field which ultimately increase parasitisation and can become a key factor for the success of biological control program.