Effect of volatiles from leaves of rice cultivars on the foraging behaviour of Trichogramma spp. (Hymenoptera: Trichogrammatidae)

Within the ecosystem of a crop field, orchard, or vineyard, various chemicals released from organisms may modify the physiology, morphology or behaviour of the other members of the ecosystem. Chemical cues play a major role in transmitting information, whether the chemicals come from various herbivores, from plants or from the interaction of the herbivores and the plants. Plant hydrocarbons act as synomones for Trichogramma spp. in a variety of crop ecosystems. Some Trichogramma species show a preference for particular host plant species, in response to an attractive synomone. We tested the possible synomonal role of leaf extracts from 29 rice varieties on the foraging behaviour and parasitism rate of Trichogramma japonicum Ashmead and Trichogramma chilonis Ishii. The results indicated that both T. Chilonis and T. japonicum showed increased parasitization when volatiles of cultivars of rice were present. While for some volatiles from cultivars like Jyoti, KCP-1, Vilirajamundi and KRH-3 the response of T. Japonicum was very high, in cases like Basmati 370, IET-8116, KRH-3, KMT-148, Kadamba, KRH-2, Jaya and VTT-5204 the response by T. chilonis was high. A response of 67.44 % was recorded to volatiles from the variety KCP-1, by T. Japonicum; whereas, a response of 82.52% was recorded to volatiles from the variety Basmati, by T. chilonis.