INCIDENCE AND ABUNDANCE OF IMPORTANT PREDATORY BEETLES WITH SPECIAL REFERENCE TO COCCINELLA SEPTEMPUNCTATA IN SUB-HIMALAYAN REGION OF NORTH Â–EAST INDIA
|Sunil KR Ghosh1 and Kaushik Chakraborty2
|Received: 21 May 2012 Accepted: 28 May 2012|
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Among the different predators coccinellid beetles play an important role in the natural suppression of destructive insect pests viz., jassid, aphid, thrips, hoppers mites and eggs of many other insect pests infesting brinjal, ladysfinger and rice crop. Coccinella septempunctata, an important coccinellid beetle in the sub-Himalayan region of north-east India was found very active on different insect pests of brinjal, ladysfinger and rice during kharif and post kharif season. This coccinellid beetle is an important biological pest control agent. Field experiment in pesticide untreated fields for three consecutive years (2005-2007) on the three different kharif crops at the agricultural research farm of Uttar Banga Krishi Viswavidyalaya, West Bengal, India showed the presence of 12 species of coleopteran beetles as generalized predator. Among them C. septempunctata was found in maximum in brinjal field and the higher was being recorded during September- October (32-38 SMW) and population declined in November. Similar seasonal incidence pattern was followed for ladysfinger and rice crop and higher average populations were achieved during October (37-38 SMW) and late September (35 SMW) respectively. Incidence of C. septempunctata showed significant positive correlation (p= 0.05) with maximum and mean temperature and significant negative correlation with maximum and gradient relative humidity and rainfall whereas with humidity gradient and rainy days the correlation was negative but non-significant.