Temperature, size, reproductive allocation, and life-history evolution in a gregarious caterpillar

The present study aimed to investigate the relation between growth rate, final mass and larval development, and how this relations influence the reproductive trade-offs in the context of a gregarious life-style and the need to keep an optimal group size. We use as model two sympatric populations of the pine processionary moth Thaumetopoea pityocampa, occurring in different seasons and thus experiencing different climatic conditions. T. pityocampa is a strictly gregarious caterpillar throughout the larval period, which occurs during winter in countries all over the Mediterranean Basin. However in 1997 a population, in which larval development occurs during the summer, was discovered in Portugal, being called Summer Population SP, as opposed to the normal Winter Population WP, which coexists in the same forest feeding on the same host during the winter. Both this populations were monitored during three years, with assessment of the length of the larval period and its relation with differe...