Occurrence of Papaya Mealybug (Paracoccus marginatus Williams and Granara de Willink) and the Field Efficacy of the Parasitoid (Acerophagus papayae Noyes and Schauff) on Mealybug Infestation in Cassava

Abstract

Papaya mealybug, Paracoccus marginatus Williams and Granara de Willink, an invasive insect pest, causes severe damage in cassava growing areas of Salem and Namakkal districts of Tamil Nadu. Field surveys conducted on the incidence of P. marginatus in Salem and Namakkal districts of Tamil Nadu showed the incidence of mealybug, which was above 60% in 13 villages of Salem district and 6 villages in Namakkal district during 2019. A field experiment on the efficacy of Acerophagus papayae on P. marginatus infestation in cassava showed 90.2 to 98% parasitization efficiency after a month of parasitoid release. The parasitoid population varied between 60 and 212 parasitoids per leaf and between 24 and 80 parasitoids per 5 cm stem. Among the ten locations studied, parasitoids recovered from the released fields ranged from 8250 to 16500 from 50 plants per acre from Aaripalayam, Pethanaickanpalayam and Ottapatti fields at 5 to 7 months after release which indicates faster multiplication of the parasitoid. The activity of the parasitoids in the released fields persisted for a longer period, till the harvest of the plant (November - December) and prevented further population build-up of the mealybug. The present investigation revealed that A. papayae as a successful biocontrol agent in sustained management of papaya mealybug.