Ecobiology of the common castor butterfly Ariadne merione merione (Cramer) (Lepidoptera: Rhopalocera: Nymphalidae)

Abstract

We describe the life history of the common castor butterfly, Ariadne merione merione, monthly occurrence and seasonality of early stages and larval performance in terms of food consumption and utilization, and the length of life cycle. Our study was conducted during 2002 in the Andhra University campus at Visakhapatnam (17°42' N, 82°18' E), South India. Field study indicated that A. merione merione was in continuous flight and reproduction, with highest densities of early and adult stages occurring during June - September, the time of the entire South-West monsoon. Occurrence of the early stages was positively, but non-significantly correlated with rainfall, relative humidity, temperature and day-length. Multiple regression analysis showed that the effect of any combination of weather parameters on the reproductive activity was less than 40%. The South-West monsoon period probably influenced the reproductive activity by promoting fresh growth of the larval host plant, Ricinus communis, which in turn supported development of early stages. Ariadne merione merione was exemplified by a life cycle of 27.4 ± 3.57 days (eggs 3-4, larvae 13-18, and pupa 6-9 days) permitting a maximum of 8-9 overlapping generations per year. The values of the nutritional indices across the instars were A.D. 87.02-95.50%; E.C.I. 3.80-20.90%; E.C.D. 4.00-24.08%, measured at 28°C in the laboratory. These relatively high values, at least partially explain the ecological success of A. merione merione in the urban environment.