Effects of Temperature and Relative Humidity on the Life Table of Pieris brassicae (Linnaeus) (Lepidoptera: Pieridae) on Cauliflower

Abstract

Abstract Pieris brassicae, the large cabbage white butterfly, has emerged as a serious pest of cauliflower in India, considering basic studies on its development and survival at different temperatures (17.5 ± 7.5, 20 ± 10, 22.5 ± 12.5, 25 ± 15, 27.5 ± 17.5, 30 ± 20 and 32.5 ± 22.5°C) at constant relative humidity (RH) of (65 ± 5%) level and photoperiod of 14:10 (Light: Dark) to ascertain optimal population growth during 2021 and 2022. A life table was constructed using temperature, humidity and photoperiod. The immature stages duration was 92.61 ± 0.99 days at 17.5 ± 7.5°C and 65 ± 5% RH, but shortened to 25.25 ± 0.35 days at 32.5 ± 22.5°C at same RH. Adult longevity of male and female was 12.30 ± 0.07 and 14.12 ± 0.04 days at 17.5 ± 7.5°C and 65% RH, but 4.44 ± 0.06 and 5.80 ± 0.05 days at 32.5 ± 22.5°C at the same RH. Fecundity was at its maximum (257.06 ± 1.46 eggs/female) at 32.5 ± 22.5°C and 65% RH, with lower fecundity at 17.5 ± 7.5°C. The net reproductive rate (Ro) and finite rate of increase (λ) were maximum 25.73 females/female/generation and 1.1184 fold per female per day, respectively at 32.5 ± 22.5°C and 65% RH suggesting that the population would increase more than 25.73 times per generation and 1.1184 times per female per day. The rates of increase at higher alternating temperatures were generally lower than at 17.5 ± 7.5°C. The intrinsic rate of increase (rm) was the highest (0.11195) at 32.5 ± 22.5°C. Our results suggest that 32.5 ± 22.5°C and 65% RH is the most favorable temperature and RH combination for the optimal population growth of P. brassicae. Our study also predicts the expansion of this pest to other parts of the world in which the average temperature equals to 32.5 ± 22.5°C with 65% RH.