Quantification of avoidable yield losses in oilseed Brassica caused by insect pests

A six year field study was conducted from 2001–2002 to 2006–2007 at Punjab Agricultural University, Ludhiana, India to study the losses in seed yield of different Brassica species (B. juncea, B. napus, B. carinata, B. rapa and Eruca sativa) by the infestation of insect pests. The experiment was conducted in two different sets viz. protected/sprayed and unprotected, in a randomized block design, with three replications. Data on the infestation of insect pests, and seed yield were recorded at weekly intervals and at harvest, respectively. The loss in seed yield, due to mustard aphid and cabbage caterpillar, varied from 6.5 to 26.4 per cent. E. sativa suffered the least loss in seed yield and harboured the minimum population of mustard aphid (2.1 aphids/plant) and cabbage caterpillar (2.4 larvae/plant). On the other hand, B. carinata was highly susceptible to the cabbage caterpillar (26.2 larvae/plant) and suffered the maximum yield loss (26.4%).