STUDIES ON FIELD BIOLOGY OF OPISINA ARENOSELLA WALKER : A KEY PARAMETER MASS TRAPPING

Coconut black headed caterpillar is a defoliating pest in East Asian countries. Due to great difficulties in managing this pest, present study was undertaken to know biology and explore the utility of BHC sex pheromone for its management. The data on field collected pupae were pooled across sites and estimated biological parameters. The sex ratio was favorable to female at all the places i.e. female biased sex ratios (1 : 1.17). But there was no significant difference in their numbers across generations and locations. Observations on adult emergence indicated that approximately 50 per cent of the pupae emerged into adults. Out of 100 per cent of male and female pupae only 45.66 and 54.25 per cent were male and female pupae, respectively. At the study site pupal parasitisation ranged between 6.67 to 21.00 per cent with an average of 14.20 + 5.46 per cent. The partial life table indicated that the survivorship rate at the larval and pupal stages were 39.37 and 49.09 per cent, respectively. In adult stage, majority of the (98.16%) moths emerged were normal and most likely to be involved in reproduction and multiplication. In mass trapping, a total of 1156 moths were trapped in 120 traps. During this period 75.00 per cent of the larvae were parasitized by Goniozus nephantidis and 21.48 per cent of pupae by Meteoridea sp., Brachymeria sp. and Xanthopimpla sp. The larval population recorded after mass trapping indicated significantly less compared to earlier generation.