Autecology of the endemic Crimson Rose butterfly Pachliopta hector (Lepidoptera : Rhopalocera : Papilionidae)

Abstract

The study including field observations on the distribution of eggs, larvae, purpae on the larval host Aristolochia indica and the laboratory study on the success rate of eggs, larvae and pupae established that Pachliopta hector Linn., endemic to Sri Lanka and south India, is on wings throughout the year with a higher density during August/September/October/November and also during AprilJune. It is multivoltine with 67 broods yearly, with development from egg to the adult requiring 3947 days. The species displayed single egg-laying habit, which coupled with host plant specialization of larve feeding on A. indica and A. bracteolata allowed efficient utiliza-tion of the food resource. The eggs hatched in seven days and the larvae passed through five instars. The last two instars consumed over 80% of the total food intake. Profiles of food consumption and body weight gain ran on similar lines, with increase through successive larvae. Both consumption index (CI) and growth rate (GR) de-clined as the larvae aged, the value of the former averaging 3.02 and the latter 0.37. The values of approximate digestibility (AD) are high: 9987%. The values of both efficiency of conversion of ingested food (ECI) and effi-ciency of conversion of digested food (ECD) increased as the larvae aged, the former averaging 18.02% and the latter 22.26%. Adults of P. hector utilized nearly 24 floral species as nectar sources, whose sugar concentrations (1258%) corresponded with 1550% in psychophilic flowers. They displayed a hovering habit while harvesting nectar, and frequently contacted the essential organs with probosics and head, thus promoting cross-pollination.