Survival patterns under Costa Rican field conditions of the gregarious caterpillar Euselasia chrysippe (Lepidoptera: Riodinidae), a potential biological control agent of Miconia calvescens (Melastomataceae) in Hawaii

Survival of Euselasia chrysippe, a natural herbivore of Miconia calvescens, was investigated under field and laboratory conditions in Costa Rica as part of a biological control program in Hawaii. Following its introduction to Pacific islands, M. calvescens has become a dominant invasive species and the gregarious caterpillar of E. chrysippe has emerged as a promising biological control candidate. Under laboratory conditions, survivorship from egg to adult was 63%. E. chrysippe produced viable clutches in an experimental field plot. Similar clutch sizes occurred in both natural habitats and the experimental plot. Stage-specific life tables encompassing two years in the experimental plot indicate that larval survivorship from egg to the end of the sixth instar was about 10%. Egg parasitism was low in natural habitats and nil under experimental conditions. Larval group sizes were similar in natural and experimental field conditions, suggesting that survivorship is similar in both environments. During the coldest dry period no larvae survived past the fifth instar. Rainfall was a limiting factor for the survivorship of E. chrysippe in the experimental plot, but temperature appears to be the factor that would limit the effect of E. chrysippe on M. calvescens in Hawaii. Efforts should be invested in natural quarantine facilities to provide a testing ground for this species in target environments.