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Biology of Pieris brassicae reared on Brassica napus, B. juncea, B. rapa, and B. carinata was studied. Adult butterflies, collected in November from the plains of Punjab, India, were sexed, paired, and released onto the four Brassica spp. in a greenhouse. In a multigeneration study (Parental, F1, and F2), the effect of the four Brassica spp. on the egg laying, incubation period and hatching percentage was assessed in a greenhouse study. Hatched larvae were collected, reared on fresh leaves of respective Brassica spp, in laboratory conditions. Data collected on larval stadia, pre-pupal and pupal durations, adult longevity, and sex ratio were assessed to understand the effects of these four species. Of the four species, B. carinata, with a shorter incubation period, higher hatching percentage, and shorter developmental periods was most susceptible. In this study, B. rapa was the most resistant species and may be recommended for further breeding programs in order to reduce the economic damage caused by P. brassicae.
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%).
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