Authors :

R. Raja Rishi*, R.K. Borah, Rajesh Kumar and Shailesh Pandey,

Author Address :

Forest Protection Division, Rain Forest Research Institute, Jorhat – 785 001 (Assam) India.

Abstract :

Boarmia variegata Moore (Geometridae: Lepidoptera), a looper  larva is one of the major pests of Melia azedarach an important fast growing tree species in North East India.  The larvae consume the leaf completely and leaving the mid vein and some basal portion of leaf while defoliation. The peak period of larval attack is during the month of June to October.  During recent years (2011-12),  B. variegata have been found to cause extensive damage by defoliating the M. azedarach seedlings kept in the nursery of  Rain Forest Research Institute, Jorhat, Assam. Most of the larvae were died naturally  due to viral infection.   It was found that the occlusion bodies (OBs) isolated from the cadaver of II instar larvae of B. variegata was found to be in a concentration of 2.06 x 1010 PIB/ml. Pathogenicity test was conducted through bioassays using the leaf dip method to confirm the effect of NPV on II instar larvae of B. variegata with four different concentrations viz. 2.06 x 1010, 2.06 x 108, 2.06 x 106, 2.06 x 104 PIB/ml in laboratory condition. The results revealed that the concentrations 2.06 x 1010 and 2.06 x 108 PIB/ml were found effective against the  larvae of  B. variegata and causing 100 percent mortality.

Keywords :

Boarmia variegata, Melia azedarach, defoliation and mortality