Host Plants, Temperature and Seasonal Effects on Immature Development and Adult Size of Euploea-Core-Corinna (Lepidoptera, Danainae)

Abstract

The suitability of four commonly used host plants of Euploea core, i.e. Cryptostegia grandiflora, Hoya australis, Nerium oleander and Parsonsia straminea, was measured in terms of developmental rates, pupal weight and adult wing length. The experimental temperature and seasonal quality of fresh shoots of the host plant affected all these variables. The results of development rates were inconsistent across host plants at different temperatures, but pupal weight and wing length of the butterfly were consistent. Despite great differences in the weight of pupae, pupal developmental rates appeared mainly affected by temperature. Fresh foliage produced in early spring gave significantly better growth of larvae than fresh foliage produced in late spring or autumn. Larvae coped with poor food quality in two distinct ways. One group moulted at approximately the right time, but at an unusually small size, the other group delayed moulting until it reached an appropriate size for moult. Losses were heavy in both groups. Overall, host plants in the Apocynaceae were more suitable for growth than those in the Asclepiadaceae, but whether the host plants were introduced or native, or whether they contained copious quantities of latex or not, did not seem to have a significant effect. The successful use of host plants in the Asclepiadaceae, like the C. grandiflora and ornamental H. australis, is therefore probably related to other factors, such as the frequency with which they produce fresh foliage and their common presence, overriding any minor differences in suitability. Key words: Euploea, developmental rates, host plants, seasonal effects.