There is growing concern that massive loss of honey bees can cause serious negative effects on biodiversity and ecosystems. Surveys of colony losses have been performed worldwide to monitor the dynamic changes and health status of honey bee colonies. Here, we present the results of surveys regarding winter colony losses from 21 provinces in China from 2009 to 2021, with a total of 1,744,324 colonies managed by 13,704 beekeepers. The total colony losses were low (9.84%; 95% Confidence Interval (CI): 9.60–10.08%) but varied among years, provinces, and scales of apiaries. As little is known about the overwintering mortality of Apis cerana, in this study, we surveyed and compared the loss rates between Apis mellifera and A. cerana in China. We found colonies of A. mellifera suffered significantly lower losses than A. cerana in China. Larger apiaries resulted in higher losses in A. mellifera, whereas the opposite was observed in A. cerana. Furthermore, we used generalized linear mixed-effects models (GLMMs) to evaluate the effects of potential risk factors on winter colony losses and found that the operation size, species, migration, migration×species interaction, and queen problems were significantly related to the loss rates. New queens can increase their colony overwintering survival. Migratory beekeepers and large operations reported lower loss rates.

Surveys of managed honey bee colony losses worldwide have become fundamental for engineering a sustainable and systematic approach to protect honey bees. Though China is a member of the world’s apiculture superpowers, the investigation of honey bee colony losses from Chinese government was not formally launched until recently. In this study, we investigated the colony winter losses of the western honey bee (Apis mellifera) of four consecutive years in 2013–2017 from 19 provinces in China, with a total of 2387 responding Chinese beekeepers (195 hobby beekeepers, 1789 side-line beekeepers, 403 commercial beekeepers) providing the records of overwintering mortality of honey bee colonies. The calculated colony losses were 8.7%, a relatively low mortality below the world average. There still exist considerable variations in total losses among provinces (ranging from 0.9% to 22.0%), years (ranging from 8.1% to 10.6%) and scales of apiaries (ranging from 7.5% to 10.0%). Furthermore, we deeply analyzed and estimated the effects of potential risk factors on the colonies’ winter losses, and speculated that the queen problems, the operation sizes and proportion of new queens are leading causes of the high honey bee colony mortality in China. More research and advanced technical methods are still required for correlation analysis and verification in future surveys of managed honey bee colony winter losses.

Polyandry is widespread among eusocial Hymenoptera, and the honey bee is a typical representative of this. It has been widely shown that polyandry can confer benefits to queens and their offspring, including enhanced productivity and fitness, stronger resistance to pathogens, and resilient division of labor, which promotes colony-level homeostasis. A previous study conducted in Australia demonstrated that 33.8% commercial Apis mellifera queens produced in autumn were not adequately mated. Beekeepers of Apis cerana in China also claimed that the queens reared in autumn are inferior to those reared in spring. To confirm whether the quality difference of queens produced in different periods is related to their mating frequency, we estimated the observed mating frequency (k) and the effective mating frequency (m_e) of A. cerana queens produced at the beginning and end of the queen production season in Liaoning Province. We found that all the queens were suitably mated and there was no significant difference in the mating frequency between early spring queens and late summer queens. In addition, our study indicated that the queens and their offspring workers owned a high level of heterozygosity and their inbreeding coefficients were universally low. Further studies on the queens’ performance and health are required to verify the statement that the queens reared in autumn are not as good as those reared in spring.

After the introduction of various Apis mellifera subspecies into China, prolonged breeding and selection have substantially altered the genetic structure and diversity of commercial populations. Currently, A. mellifera has become the most widely managed and numerically dominant honey bee species in China, providing important agricultural pollination services and substantial economic benefits. Nevertheless, the genetic diversity and progenitor of commercially managed A. mellifera populations within different regions in China remain poorly understood. To assess the maternal lineage diversity of A. mellifera populations and to support regional breeding strategies, we examined DNA sequence diversity in the cytochrome C oxidase I (COI) and tRNAleu-COII gene segment of the mitochondrial genome in 178 samples of A. mellifera drones from 12 sites in the urban districts of Beijing. Three haplotypes were found for the COI gene segment, and eight haplotypes were discovered for the tRNAleu-COII gene segment. Mitochondrial sequencing revealed that the frequency of C evolutionary lineage dominates in A. mellifera populations in Beijing. In addition, one unexpected haplotype from the Z lineage was detected. The subspecies Apis mellifera ligustica, representing the C1 haplotype, demonstrates the widest distribution and highest frequency. Our results also showed that significant genetic differentiation exists among commercial populations of A. mellifera in the urban districts of Beijing.