Biology and seasonal activity of semilooper, Dichromia orosia (Cramer) (Lepidoptera: Noctuidae) on anthmool, Tylophora asthmatica Wight and Arn.

Abstract: Dichromia orosia (Cramer), a near monophagus pest was observed to cause severe defoliation to its host plant, anthmool (Tylophora asthmatica Wight and Am), an important medicinal plant used in Ayurvedic formulations to treat asthma world over. Biology and seasonal activity of the pest was studied during 2009-10 at Anand, Gujarat. Though incidence was observed throughout the year, however, the pest activity was more during July, August, December, January and February months. The pest completed its life cycle in 24.53?0.40 days (Eggs 3-4, larvae 10-14 and pupae 6-7 days). The longevity of the male and female was 15.70?0.68 and 19.70?0.42 days, respectively. Each female laid an average of 178.5?17.66 eggs, mostly on the under surface of the leaves in 12.20?0.49 days of oviposition period. The larvae developed through five instars in 12.9?0.35 days and pupal period lasted for about 6.8?0.11 days. Correlation of peak pest population periods with corresponding and previous Standard Meteorological Weeks (SMW) revealed that prevalence of maximum temperature (27.5-30.2⁰C) mean temperature 29.31 ⁰C, high RH and low rainfall recorded in increase of larval population.