Kairomonal Effects of bio-active plant extracts on spider population and parasitization of yellow stem borer eggs by Trichogramma japonicum

Host location and acceptance by egg parasitoids can be mediated by various allelochemicals. In this study, we tested the response of Trichogramma japonicum Ashmead to bioactive plant extracts of easily available plants against Scripophaga incertulas (Walker). An experiment was laid in free choice conditions at Raipur (Chhattisgarh agro-ecosystem) in randomized block design with seven treatments including control. There was continuous increment in parasitization by T. japanicum for up to 15 days. Parasitization T. japanicum was enhanced significantly in Tagetes erecta (Marigold) treated plots (48.5%) followed by Ocimum sanctum(Tulsi) (42.6%) and was minimum in Azadirachta indica (Neem) treated plots (18.8%). Tagetes erecta (Marigold) spray on rice crop elicited a positive response in spider population, with the highest average number of spiders (5.80), followed by control 3.66%. The other treatments showed repellent action on spider population.