Molecular Entomology, 2025, Vol.16, No.1, 28-38 http://emtoscipublisher.com/index.php/me 30 may prosper. Pope et al. (2023) analyzed the genome of the North American pumpkin bee (Eucera pruinosa) and found that the widespread cultivation of pumpkins and other cucurbit crops by humans has significantly changed the evolutionary trajectory of this pollinator in the last thousand years: the pumpkin bee population has expanded rapidly, and chemical perception-related selection sweeps have appeared in the genome, which is presumably the result of adapting to the single floral fragrance environment of crops. 2.3 Habitat fragmentation and landscape change Agricultural reclamation and urban expansion have led to the fragmentation of pollinator habitats, with habitat patches separated by farmland and artificial landscapes. This change in landscape scale has a significant impact on the gene flow and genetic structure of bee populations (Panziera et al., 2022). When habitat fragmentation is severe, bee populations are often confined to smaller habitat patches, and individual communication between populations is hindered, which in turn leads to inbreeding and decreased genetic diversity in local populations. From the perspective of genetic evolution, when the landscape hinders gene flow, each isolated population may evolve independently under the action of natural selection and genetic drift, leading to genetic differentiation. Espregueira Themudo et al. (2020) analyzed the genome of European honey bees and found that under the influence of human activities in the last century, the nucleotide diversity of its two major lineages (Western European M lineage and Central European C lineage) was significantly reduced, and some functional genes (such as the royal jelly protein gene family) showed signs of selection, which may be related to the genetic homogenization caused by the introduction and breeding of beekeeping. 2.4 Commercial beekeeping and population genetic disturbance Commercial beekeeping has a dual impact on bees and other pollinators: on the one hand, it improves crop pollination, but on the other hand, it may also disrupt the genetic structure and health of wild populations. Large-scale mobile beekeeping and cross-regional transportation of bee colonies have broken the original geographical isolation of bee populations and mixed the genetic backgrounds of bees from different regions. This artificial introduction and hybridization may lead to a reduction in the genetic purity of local bee subspecies or strains, and the unique adaptive genome is diluted by foreign genes. For example, after the introduction of excellent varieties such as Italian honey bees and Carniola honey bees, the native black bees (Apis mellifera mellifera) in many parts of Europe have undergone extensive hybridization, and the genetic characteristics of local bee species have gradually been lost (O’Neal et al., 2018). In addition, commercial beekeeping generally adopts artificial breeding, tending to select high honey production and docile traits, resulting in a relatively narrow genetic base for queen bees used in the global beekeeping industry. Over time, the genetic diversity of farmed bee colonies will decrease, which not only increases the vulnerability of bees to diseases and environmental changes, but also further reduces the diversity of wild populations through intermarriage with wild bees. On the other hand, commercial beekeeping may also affect wild pollinators through the spread of pathogens (Belsky and Joshi, 2019). Bees raised in high density in beehives often carry pathogens such as viruses and fungi. Mobile beekeeping can cause these pathogens to spread between regions and spill over to infect wild bees and bumblebees. 3 The Importance of Bees in Agricultural Ecosystems and the Problems They Face 3.1 The ecological role of bees as pollinators Bees have irreplaceable ecological functions in agricultural ecosystems. As pollinators, bees help a large number of crops complete the pollination process, improve the fruit set rate and fruit quality. Research statistics show that bees contribute a considerable proportion of crops that mainly rely on animal pollination. For example, in field trials of economic crops such as fruits, nuts, and oilseeds, bee pollination can increase yields by more than 20% to 50%. The efficient foraging behavior of bees enables them to visit many flowers in a short period of time, promote the transfer of pollen between different flowers or plants of the same plant, and thus increase the fruit set rate and fruit size of crop seeds (Gazzea et al., 2023). Bees promote plant fruiting through pollination, which not only benefits vegetation renewal, but also provides food resources for other fruit-eating and seed-eating animals.
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