Implications of the hive materials and mtDNA haplotypes on honey bee <i>Apis mellifera</i> thermoregulation and colony weight

Innovative hive materials could reduce stress from high temperatures and adverse weather conditions for honey bee colonies, Apis mellifera L. (Hymenoptera: Apidae). This study compares traditional Langstroth wooden hives with those made from polyurethane (PU) with respect to thermoregulation and performance of four mtDNA honey bee haplotypes from June to December. The weight, internal temperature, and humidity of 10 colonies kept in PU hives and 10 colonies kept in wooden hives were continuously monitored. At the same time, brood production, Varroa infestation levels, and deformed wing virus levels were assessed once mid-experiment. No differences were observed in brood production, Varroa infestation, or viral loads between hive groups. However, PU hives maintained significantly higher average internal temperature (34.3 °C) and lower relative humidity (57.2%) compared to wooden hives (32.8 °C and 60.2%, respectively). Overall, weight loss was significantly higher in wooden hives (4.8 kg) compared to PU hives (0.8 kg), and a significant seasonal component in thermoregulation and weight was also observed. Four honey bee haplotypes were identified: C1 (A. m. ligustica), C2d and C2j (A. m. carnica), and M2-1021-7-USA (A. m. mellifera). Within each hive group, haplotype variance significantly affected colony thermoregulation and weight. Hive temperature and weight were correlated regardless of the hive material. The haplotype C1, Italian bees, a common haplotype in the USA, recorded the highest temperature and weight in wooden hives. This study demonstrated significant impacts of hive materials on honey bee colony thermoregulation and performance.