Field life tables and key mortality factors of Pieris brassicae (Linnaeus) (Lepidoptera, Pieridae) infesting cauliflower (Brassica oleracea var. botrytis) in Punjab, India

Abstract

To find out the key mortality factors of Pieris brassicae (Linnaeus) on cauliflower (Brassica oleracea var. botrytis), this study of field life table was conducted during 2021-22 at the research farm of the Punjab Agricultural University, Ludhiana, Punjab. Among biotic factors, Cotesia glomerata, Beauveria bassiana (Bals.), NPV, Bacillus thuringiensis (Berliner) were the main causes of mortality. Other unknown factors (temperature, rainfall, relative humidity) also contrived slight decline to all the immature stages of    P. brassicae. Results revealed that the egg stage (17.46-28.35%) affected due to unknown factors, whereas, early larval instar stage (I-III) was the most sensitive, showing the highest loss (36.62-43.95%) followed by the late larval instar stage (25.77-29.43%) and pupal stage (16.19-22.41%). The trend index was positive   uring both seasons 16.91 (main season) and 19.17 (late season), indicating that population of P. brassicae increased in next season. Similar trend was observed in generation survival i.e. 0.39 (main season) and 0.32 (late season).