INFESTED AREAS OF MAJULI, ASSAM, INDIA

Entomopathogenic nematodes (EPNs) in the genera Steinernema and Heterorhabditis and their associated bacteria such as Xenorhabdus spp. and Photorhabdus spp. are lethal parasites of soil dwelling insects. A survey was conducted to collect theentomopathogenic nematodes from Lepidiota mansueta endemic field of Majuli river island, Assam, India. During the survey, a total of 140 soil samples (1 kg each) and 80 dead grubs of L. mansueta were collected from different locations from cultivated as well as uncultivated fields of Majuli. Out of the total collection, 8 numbers of soil samples and 35 grubs were positive for entomopathogenic nematodes with 5.7 and 43.7 per cent respectively. Soil samples recorded 2.1 and 3.5 per cent Heterorhabditis and Steinernema isolates whereas the grubs registered 15 and 28.7 per cent of Heterorhabditis andSteinernema isolates respectively. Based on morphometric and cross-breeding studies, the Heterorhabditis isolates were identified as H. bacteriophora and this species was recovered from diverse habitats with different soil characteristics. Being a river island, the soil of Majuli may be the reservoir of many more species of EPNs which needs further study.