Effect of different cole crops on the biological parameters of Pieris brassicae (L.) (Lepidoptera: Pieridae) under laboratory conditions

摘要

The effect of different cole crops was studied on biological parameters of Pieris brassicae (L.) in the laboratory at 28 °C, 65% RH, and 12L:12D photoperiod. The results indicated that host plants significantly affected the life history, i.e. survival of developmental stages, oviposition period, and sex ratio of P. brassicae. Comparative study on different host plant revealed that P. brassicae required a maximum of 40 days to complete generation on cabbage, cauliflower, and broccoli. The survivorship and expectation of life declined gradually with the advancement of age; the life expectancy of newly deposited eggs was 23.96 days while it was 8.12 days at the time of adult emergence on cabbage. However, the fluctuations of mortality parameter were seen on all the cole crops. On cabbage, 100% hatching of eggs with low larval mortality were noticed. The highest net reproductive rate (R₀) occurred on cauliflower, i.e. 27.1 followed by cabbage 24.89, females per female per generation. Intrinsic rate of increase (r_m), was found to be highest (0.09558954) on cauliflower followed by broccoli and cabbage, 0.078886 and 0.077551 females per female per day, respectively. The smallest r_m (0.059469 females per female per day) occurred on radish which shows that P. brassicae did not perform well on radish. In addition, P. brassicae may double in 7.2 days on cauliflower, 8.7 days on broccoli, and 8.9 days on cabbage. The sex ratio was computed as 1.5:1, female:male, respectively on cabbage.