Relationship between copulation and cold hardiness in Ophraella communa (Coleoptera: Chrysomelidae)

Ophraella communa (Coleoptera: Chrysomelidae), the ragweed leaf beetle, is a biological control agent of the invasive common ragweed, Ambrosia artemisiifolia (Asterales: Asteraceae). Adults can survive cold conditions that occur during winter. The adults mate before entering overwintering. Understanding the connection between copulation and overwintering will be useful for determining O. communa seasonality. Determining the relationship between overwintering and copulation required comparison of mated and unmated beetles at mean lethal temperature (LTemp(50)) exposures for 2 h. Cold-related physiological indices, including the water ratio, super cooling point (SCP), cryoprotectant levels, and energy reserve levels, were also measured. Mating treatment decreased the LTemp(50) of both sexes by reducing their mean SCP and water ratios. Although the changes of cryoprotectant levels in mated adults were not precisely consistent in between the genders, they increased greatly in both males and females. Body sugar may play a role in copulation and may also elevate cold hardiness in O. communa.