Bioecology and control of Lipaphis erysimi (Kal.) (Homoptera: Aphididae) on certain cruciferous plants
- L. Chitra
- Ph. D Thesis, Manipur University,
The aphid, Toxoptera aurantii (Boyer de Fonscolombe) is an important pest of tea infesting tender leaf and shoot from March to October with density of 200 of the tea twig. Such severe infestation leads to delayed recovery of the plant with the consequent effect on poor crop productivity. Periodical sampling revealed the occurrence of five species of predatory syrphids viz., Paragus serratus Fabr., Episyrphus balteatus (De G), Betasyrphus serarius (Weid), Metasyrphus confrater (Weid) and Ischiodon scutelleris (Fabr.); four species of coccinellids viz. Coccinella septempunctata L., C. transversalis Fabr., Oenopia sexareata (Mulsant) and Coleophora bisselitta Mulsant and a neuropteran, Micromus timidus Hagen along with the colony of T. aurantii. Seasonal abundance of predators synchronized with the pest with a maximum occurrence during September. Correlation between the density of aphid and its predators revealed a significant positive relation and the feeding rate of different predatory species ranged from 136 to 460 aphids per larva. Of which C. septempucta recorded the maximum of 460 aphids and E. balteatus with 136 aphids per larva. Though the feeding propensity of the predators differs from species to species, their presence in the field prevents the aphids from becoming a serious pest.