Feeding Potential of Grubs of larvae of Syrphid and Coccinellid Predators on Mustard Aphid, Lipaphis erysimi

摘要

Among the insect pests attacking rapeseed and mustard aphid, Lipaphis erysimi (Kaltenbach) is a serious insect pest, infesting the crop right from seedling stage to maturity. The losses in yield caused by mustard aphid ranged from 9 to 95% (Singh et al, 1980), 35.4 to 72.3 per cent (Bakhetia, 1986), 24.00 to 96.00 per cent (Phadke, 1985) and up to 96% (Verma, 2000) at different places in India. The infestation of pest not only results in reduced yield of the seeds but also reduces the oil content upto 66.87 % (Singhvi et al, 1973). Among the natural enemies of this pest, syrphid flies (Syrphus confrater, Syrphus balteatus and Ischiodon scutellaris) and lady bird beetle, (Coccinella septempunctata Linn.) are the important entomophagous predators under field conditions (Shukla etal, 1990). The present studies were undertaken to make quantitative estimates of preying capacities of different larval instars, of Syrphus confrater (Weid.), Syrphus balteatus (Deg.), Ischiodon scutellaris (Fab.) and Coccinella septempunctata (Linn.) on mustard aphid, Lipaphis erysimi (Kalt.).