Status of coconut black headed caterpillar, Opisina arenosella (Walker) and it’s associated larval parasitoid, Goniozus nephantidis (Muesebeck) under south Gujarat conditions

Abstract

Roving survey has been carried out in major coconut growing talukas of Navsari district viz; Navsari, Jalalpore, Gandevi, Chikhali and Vansda to know the exact status of the pest black headed caterpillar and its associated larval parasitoid, G. nephantidis during the year 2015-16 and 2016-17. Pest incidence, Pest intensity and Parasitization percentage has been recorded during survey work. Overall survey results revealed that pest incidence of coconut black headed caterpillar, O. arenosella was observed in all talukas throughout the year in the range of 18.79 to 54.92 per cent in Navsari district. Maximum pest incidence was recorded in Vansda taluka (54.92%) and minimum pest incidence was recorded in Navsari taluka (18.79%). Pest intensity was in the range of 8.61 to 52.95 per cent in various talukas of Navsari district. Maximum pest intensity was recorded in Vansda taluka (52.95%) in the month of April while minimum pest intensity was recorded in Navsari taluka (8.61 %) in the month of January. Pest incidence and pest intensity trend showed that peak incidence was recorded during summer months that are from April to May while it decreases from September onwards and reaches to minimum in winter months November and December. In case of percent parasitization, G. nephantidis was the dominant parasitoid under Navsari conditions of Gujarat state. Maximum parasitization was observed in Navsari taluka in the month of May (11.76 %) followed by April (10.07 %) while lowest was 2.63 per cent in Chikhali taluka in the month of May.