Role of egg parasitoid, Trichogrammatoidea bactrae Nagaraja alone and in combination with dichlorovos in the management of Plutella xylostella (Linnaeus) on cabbage

摘要

The optimum release dosage of Trichogrammatoidea bactrae Nagaraja and its comparative efficacy alone and in combination with dichlorvos against diamondback moth (DBM), Plutella .xylostella (Linnaeus) on cabbage was worked out. Results of the study onthe percentage parasitization under different host-parasitoid ratios revealed that the maximum DBM egg parasitization (83.0%) was recorded in the ratio 100 (eggs): 5 (females), which was on par with other higher ratios of 100:10 to 100:20. The release ofT. bactrae twice (2 and 5 days after DBM moth release) proved as the most effective treatment in significantly reducing the larval population (4.89 larvae per plant) in comparison to two sprays of dichlorvos (0.05%) (14.54 larvae per plant), The resultsindicated the efficacy of T. bactrae in suppressing DBM on cabbage and calls for further evaluation in field trials.