Effects of mating status on cold tolerance in small hive beetle, Aethina tumida

The small hive beetle (SHB) Aethina tumida Murray, (Coleoptera: Nitidulidae) has become a global pest of honey bees, but to date its adults’ cold tolerance has not been explored. Mating increases the cold tolerance in some insects. Therefore, we appraised the effect of mating on overwintering traits; Supercooling points (SCPs) and, lower lethal temperatures. We also assayed the phenotypic plasticity of SHB adults and subsequent reproductive capacity of SHB females. The supercooling points occurred at lower temperatures (-10.8℃) in mated females than in the other tested adults (mated males: -9.1℃, unmated males: -8.5℃, and unmated females: -8.0℃). The sum of injurious temperature (SIT) was the utmost expedient estimation to characterize that mated females were the most cold-resilient (-119.8 DD). Acclimation mitigated the detrimental effects of lethal temperatures and increased egg laying compared with their counterpart control. However, this phenotypic plasticity of SHB females reduced egg laying of mated and unmated females (23.7, 25.0 eggs/female, respectively) by comparison to laboratory reared untreated females (31.4 eggs/female). Our results revealed that SHB adults are chill-susceptible regardless of their mating status but have the ability to show phenotypic plasticity. Females irrespective of their mating status, paid the reproductive cost for this plasticity. The mating neither provides any advantage to SHB females to survive cold temperatures nor the subsequent reproductive output. However, mating does reduce the cold tolerance in SHB males. This study predicts that phenotypic plasticity still could be supplementing the expansion of SHB to higher latitude areas, markedly in the scenario of climate change.