Seasonal Incidence of Major Insect Pests of Cabbage with Their Natural Enemies

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A field experiment was conducted at Horticulture Farm, Rajasthan College of Agriculture, Udaipur during rabi 2012–13 to investigate the seasonal incidence of major insect pests and their natural enemies in cabbage. The incidence of aphid was observed to be initiated in the third week of January, while that of diamond back moth, Spodoptera litura, and flea beetle commenced in the fourth week of January. The population of aphid, diamond back moth, S. litura and flea beetle was at its peak during second week of February (88.20 aphids/ten plants), fourth week of February (13.10 larvae/five plants), fourth week of February (16.12 larvae/five plants), and third-fourth week of February (22.50 beetles/five plants), respectively. The aphid exhibited a negative non significant correlation with temperature, positive but non significant correlation with humidity, and positive significant correlation with rainfall. The diamond back moth and S. litura exhibited a positive significant correlation with temperature and negative non significant correlation with relative humidity and rainfall. The population of beetles had a positive but non significant correlation with temperature, relative humidity and rainfall. The incidence of natural enemies-Coccinella septempunctata, Diaeretiella rapae and Chrysoperla carnea started in the third week of January. The population of C. septempunctata (15.63/five plants), D. rapae (5.85/five plants) and C. carnea (2.90/five plants), was at its peak during second week of February, with their seasonal incidence exhibiting a positive but non significant correlation with temperature, relative humidity and rainfall.