Grub Density of Lepidiota mansueta (Coleoptera: Scarabaeidae) in Different Habitats of the Majuli River Island of Assam, India

Grub density of Lepidiota mansueta beetle was assessed in five ecologically different habitats viz., open grassland; open cultivated land; cultivated field near tree; grassland near stream and cultivated land near stream on the basis of soil sampling carried out in five selected villages of the Majuli river island of Assam. Highest mean density of grub (8.0 and 6.5/m3) was recovered from grasslands near stream, followed by open grassland (4.6 and 4.7/m3), cultivated field near stream (1.8 and 1.4/m3), open cultivated field (1.1 and 1.2/ m3) and cultivated field near tree (1.0 and 1.2/m3) during 2011 and 2012, respectively. Fortnightly soil sampling conducted in grassland and cultivated land revealed that grubs of L. mansueta were confined in the upper most layer of soil (0–20 cm depth) during summer season (April–September) and moved to deeper soil layers during winter season (October–March). Majority of the grubs (81.83 per cent in grassland and 72.73 per cent in cultivated land) were recorded within the...