Overwintering inside the food in the diapausing larvae of pomegranate fruit moth

Low temperatures are a major survival challenge for insects living in temperate zones. The most common features that guaranty survival in the most overwintering insects are diapause and cold hardiness. In spite of obvious advantages, damages due to diapause associated stresses such as cold shock and depletion of energy reserves make diapause a costly life history strategy. Apomyelois ceratoniae (Zeller), a major pest of pomegranate in Iran, overwinters as different larval instars. In comparison to larger counterparts, early instars of pomegranate fruit moth must have sequestered fewer energy reserves thus they might be less tolerant to cold. By designing experiments similar to natural conditions in December, we demonstrated that overwintering inside pomegranate fruits provides opportunity for larvae to feed and compensates energy depletion. Our results also indicated that there is no significant difference between supercooling point and cold tolerance of the small and the large field collected larvae during autumn and winter, thus overwintering mortality might not be a key driver in population dynamics.