Population dynamics and management of mango leaf cutting weevil, Deporaus marginatus pascoe in Arunachal Pradesh

The incidence of mango leaf cutting weevil, Deporaus marginatus P. was studied on seven cultivars of mango viz. Dashehari, Mereh, Ratul, Ramkhera, Mallika, Alphanso and Amrapali during 2010 and 2011 at Pasighat, Arunachal Pradesh. This was the first report of this pest in Arunachal Pradesh. All the cultivars were susceptible and incidence was low during winter and gradually increased from March and the highest infestation was observed during June to September. Highest incidence of 81.78% was observed in Alphanso during September 2010 and 88.96% in Mallika during September 2011. The cultivars Amrapali and Mallika recorded highest average incidence during 2010 and 2011, respectively, however, Alphanso was the least infested. The % infestation exhibited positive correlation with rainfall, RH, maximum and minimum temperature. The combined influence of abiotic factors strongly influenced the buildup of pest population. The coefficient of determination (R2) values between the pest incidence and abiotic factors were 0.933 and 0.966 in 2010 and 2011, respectively. The organic insecticides viz. neem oil, pestoneem, M. azadirach crude extract, M. azadirach fermented leave extract, M. azadirach boiled leaves extract and fermented bamboo shoot extract were comparable with cypermethrin. The treatment with cow urine alone and cow urine + ghee were found least effective.