SPATIAL-DISTRIBUTION OF KEY PESTS OF MUSTARD AND THEIR NATURAL ENEMIES IN INDIA

In a field study of the spatial distribution of the pests of mustard, Brassica campestris; Lipaphis erysimi (Kaltenback) and Athalia proxima Klug. and predator Coccinella septumpunctata Linn. attack on Lipaphis erysimi at Shillong, Meghalaya in 1984–1985. Various statistical parameters were calculated for each set of observation. L. erysimi on leaf, shoot, inflorescence and pod and A. proxima larvae on plants followed the negative binomial while the predator C. septumpunctata on L. erysimi and the larvae of A. proxima on leaves followed a positive binomial distribution. These parameters will be used to develop sequential sampling plans and economic injury levels for mustard pests. An interesting predator‐prey relationship, where the host is overdispersed and the predator is underdispersed was found, suggesting that this predator can be successfully used to control the aphid population. © 1990 Taylor and Francis Ltd.