Department of Entomology, Himachal Pradesh Krishi Vishvavidyalaya, Palampur-176 062 (H.P.) (India).
Biology of Myzus persicae Sulzer was studied under laboratory conditions on the potted plants of raya (Brassica juncea), sarson (Brassica campestris var. brown sarson) and toria (Brassica campestris var. toria). The maximum temperature varied from 19.8 to 26.0°C, minimum 13.1 to 16.7°C and R.H. 46.22 to 62.07 per cent. The aphid was observed to undergo four nymphal instars on all the three crops, the average nymphal period being 11.72, 12.05 and 12.45 days on rays, sarson and toria, respectively. Total life span of the aphid on raya, sarson and toria was respectively completed in 36.52, 42.80 and 44.85 days. Fecundity per generation of the aphid was significantly more on toria as compared to sarson and raya.
