Population fluctuations of sugarcane woolly aphid, Ceratovacuna lanigera Zehntner (Homoptera: Aphididae), and its natural enemies in plant and ratoon sugarcane crops in Assam

The seasonal incidence of sugarcane woolly aphid, Ceratovacuna lanigera Zehntner (Homoptera: Aphididae), and its natural enemies was studied at Instructional-Cum-Research (ICR) Farm, Assam Agricultural University (AAU), Jorhat and at Sugarcane Research Station (SRS), Buralikson, Golaghat during 2004–05. Out of five species of natural enemies recorded at ICR Farm, AAU, Jorhat, Eupeodes confrater (Wiedemann), Chrysoperla carnea (Stephens), Coelophora biplagiata (Mulsant) and Dipha aphidivora (Meyrick) had significant positive impact on sugarcane woolly aphid population, while non-significant negative correlation of aphid population was observed with the population of Encarsia flavoscntellum Zehntner. Multiple regression analysis of different natural enemies with the population of C. lanigera showed 89.0 per cent relationship with the aphid population. At SRS, Buralikson, Golaghat, the only observed natural enemy D. aphidivora showed significant positive impact on woolly aphid population.