Seasonal abundance of ecto-larval parasitoids of coconut black headed caterpillar, Opisinia arenosella Walker under south Gujarat conditions

Abstract

Survey was conducted in coconut plantations to document the natural occurrence of larval parasitiods of black headed caterpillar under Navsari conditions from January 2015 to December 2015 and results revealed that two larval parasitoids viz., Goniozus nephantidis (Muesebeck) (Hymenoptera: Bethylidae) and Habrobracon hebetor Say (Hymenoptera: Braconidae) were noticed on Opisinia arenosella Walker (Lepidoptera: Crytophasidae). Among them, G. nephantidis was the dominant species under Navsari condition of Gujarat state. The maximum parasitism of O. arenosella by G nephantidis and H. hebetor was observed during 2nd fortnight of May (17.69 and 15.65%) for the both parasitiods, respectively. However, the lowest per cent of parasitism by G nephantidis was found during 1" fortnight of the October (2.23%). Moreover, the per cent parasitism of H. hebetor was nil during 1" fortnight of the August to 1 fortnight of the September. The highest numbers of O. arenosella larvae were parasitized by G. nephantidis and H. hebetor during 2nd fortnight of May (52 and46 larvae), respectively. The total number of adults of G nephantidis and H. hebetor emerged from host larvae were maximum during 2nd fortnight of May (347 and 213 adults), respectively. Moreover, the number of adults of G. nephantidis emerged from single larva was highest during 2nd fortnight of the September (8.80 adults/larva). While, the maximum adults of H. hebetor emerged from single larva was noticed during 2nd fortnight of the February (7.57 adults/larva).