Impact of Inundative Releases of Parasitoids (Bracon hebetor and Goniozus nephantidis) against Coconut Black Headed Caterpillar under Severe Infestations

Caterpillar of coconut black headed caterpillar (Opisina arenosella) attacks palms of any age from nursery to grown up plants causing severe damage to the foliage and resulting in yield losses up to 50 percent. During 2023-24, a high infestation of black headed caterpillar was observed in the Dr.B.R. Ambedkar Konaseema, West Godavari and Eluru districts of Andhra Pradesh with the incidence ranging from 21.29 to 68.55% from January 2023 to June 2024, A total of 15 lakhs numbers of larval parasitoids Bracon hebetor and Goniozus nephantidis were released in pest affected coconut plantations. To study the impact of the parasitoid releases, 10 leaflets/ palm were randomly collected from three sample gardens in three villages (Allipalli, Appanacheruvu and Sannavilli) and the pest population recorded., Larval population of O. arenosella in the affected gardens decreased by 19.59 -30.64 percent after three months and up to 72.79-85.16 percent after six months of release of parasitoids and no leaf damage and pest population was recorded in the newly emerged leaves. In the random leaflet samples collected the percentage of parasitized larval population recovered was 2.18-3.52 per cent after three months and increased to 12.69-34.59 per cent after six months of release of parasitoids. After six months of release the impact of inundative release of bioagents in the suppression of the pest was visible as pest population could be brought down to very negligible level by the timely release of stage specific parasitoids.