Biology of cabbage aphid, Brevicoryne brassicae L. on toria sarson and raya

Biology of Brevicoryne brassicae L. on these oilseed crops revealed the presence of only four nymphal instars. Total nymphal period on toria (Brassica campestris var. toria), sarson (Brassica campestris var. sarson) and raya (Brassica juncea) was respectively completed in 9–12, 10–11, and 11–13 days in flowering stage as compared to 10–12, 10–12, and 12–14, days during vegetative stage. Also, adult longevity in flowering stage (26.3–29.5 days) was significantly lower than during vegetative stage (29.9–32.3 days). The same trend was observed in respect of total life span, being 37.25–42.25 days in flowering stage vis-a-vis vegetative stage (41.5–45.0 days). Fecundity and reproductive rate were also higher during flowering stage when compared with vegetative stage on all these three crops. But, the overall development of cabbage aphid was faster on toria than on sarson and raya.