Evaluation of Goniozus nephantidis (Muesebeck) a larval parasitoid in the field against coconut black headed caterpillar (Opisina arenosella Walker) in Karnataka.

Abstract

A field trail was carried out on coconut black headed caterpillar in a farmer field at Kaidalu, Tiptur Tq. Tumkur Dist. Karnataka during 2014-16 following Central Plantation Crop Research Institute guidelines. Larval parasitoid Goniozus nephantidis was mass multiplied in the laboratory for conducting the experiments. The parasitoids were pre-conditioned to the odour of larval frass for about 48 to 72 hours in the laboratory prior to release in the field. Before releasing the parasitoids, a pre-treatment count on the number of Opisina larva/ leaflet was recorded. Parasitoids were released @ 20 per palm. Four releases were made at 10 days interval during the experimental period. Each treatment was replicated on 10 palms. An untreated control (check) was also simultaneously maintained. The three years pooled data indicated that there was a higher initial larval population ranging from 21.46 to 22.19 numbers per ten leaflets in October month without parasitization which gradually decreased to 1.87 numbers/ten leaflets in treatment T1 (Conditioned) with 67.95 per cent parasitization and 4.50 numbers/ten leaflets in treatment T2 (Unconditioned) with 58.45 per cent parasitization. In untreated control, larval population of 17.64 numbers/ ten leaflets with 3.61per cent parasitisation was recorded and it showed an increase in larval population. The conditioned parasitoids were more efficient in reducing black headed caterpillar population with higher per cent parasitization compared to un-conditioned parasitoid.