Bee mortality in agriculture, particularly in avocado production, raises questions about the well-being of these essential pollinators. Bees play a fundamental role in global ecosystems and food systems, contributing to the pollination of approximately 75% of crop species and 88% of flowering plant species. Understanding the specific challenges bees face in large-scale farming provides insight into how agricultural practices intersect with pollinator health.
Avocado Pollination and the Role of Bees
Avocado trees have a unique flowering characteristic called synchronous dichogamy, making insect pollination, particularly by bees, crucial for fruit production. Individual avocado flowers open at different times as either female or male. For instance, an “A type” avocado flower opens as female in the morning, closes, then reopens as male the following afternoon. Conversely, “B type” flowers exhibit the opposite pattern. This synchronized but alternating opening mechanism often necessitates cross-pollination between different avocado varieties for optimal fruit set.
Honeybees are crucial for this process, visiting both female and male-stage avocado flowers to facilitate pollen transfer. While collecting nectar or pollen, bees contact the flower’s reproductive parts, depositing pollen grains on the stigma. A single bee visit might only deposit a small number of pollen grains, meaning multiple visits per flower are often needed for successful fertilization. Commercial avocado yields heavily rely on these insect pollinators, as local bee populations may not be sufficient for large monoculture farms. This reliance frequently leads to migratory beekeeping, where hives are transported to avocado orchards during flowering periods.
Factors Affecting Bee Health in Agriculture
Agricultural practices introduce several stressors that can compromise bee health. Pesticides, including neonicotinoids and pyrethroids, are a concern. These chemicals can directly harm bees through contact or ingestion of contaminated pollen and nectar, or indirectly by reducing their food sources. Research indicates that neonicotinoids, even at sublethal doses, can impair bee reproduction, navigation, and memory, with effects persisting across generations. For example, a study showed female bees exposed to imidacloprid as larvae had 20% fewer offspring, and those exposed as both larvae and adults had 44% fewer offspring.
Habitat loss from monoculture farming limits the diversity of forage available to bees. This lack of varied nutrition can weaken bee immune systems, making them more susceptible to diseases. Migratory beekeeping, while meeting pollination needs, stresses bee colonies. Frequent transportation disrupts colony rhythms, exposing bees to changes in daylight, temperature, and floral types. This stress weakens immune responses and shortens individual bee lifespans.
Bees also contend with various diseases and parasites exacerbated by agricultural conditions. Varroa mites ( Varroa destructor ) are external parasites that feed on bees and transmit viruses, leading to physical deformities, reduced lifespan, and compromised immune systems. Heavy infestations can cause colony collapse. Another common threat is Nosema spp., an internal parasite affecting a bee’s gut, leading to dysentery and a reduced lifespan. The close proximity of many colonies in migratory beekeeping setups can accelerate the spread of these diseases and parasites.
Understanding Bee Mortality in Farming
Bee mortality in agriculture, including avocado farming, results from multiple factors. While some bee death is natural, farming practices elevate mortality rates. For instance, U.S. commercial beekeepers reported an average 62% colony loss between June 2024 and February 2025. In Colombia, mass bee deaths have been directly linked to increased pesticide use in commercial avocado and citrus farming, with some beekeepers losing a third of their hives or even hundreds of hives. Acute pesticide exposure can lead to immediate bee death.
Even if not immediately lethal, pesticides cause sublethal effects that shorten a bee’s lifespan and compromise foraging, leading to colony decline. Bees can also bring contaminated pollen or nectar back to the hive, poisoning the entire colony. The stress from migratory beekeeping, combined with poor nutrition and disease, contributes to significant bee deaths and colony losses.
Promoting Healthy Bee Populations
Supporting bee populations in agriculture requires a multi-faceted approach. Pesticide management is a primary strategy, including Integrated Pest Management (IPM). IPM focuses on preventing pest issues first, using chemical treatments only as a last resort with careful consideration for bee safety. This includes timing pesticide applications to avoid peak bee activity, selecting bee-friendly products, and ensuring clear communication between farmers and beekeepers regarding spraying schedules.
Diversification of crops provides bees with a broader range of floral resources, enhancing their nutrition and overall health. Planting a variety of flowering plants throughout the growing season ensures a continuous supply of pollen and nectar, which is particularly beneficial for bee immune responses. Creating pollinator habitats, such as wildflower strips or hedgerows within or around agricultural fields, offers additional forage and nesting sites for both managed and wild bees. These habitats can also improve soil health and natural pest control.
Sustainable beekeeping practices foster healthier bee populations. This involves prioritizing bee well-being over maximum honey production, allowing bees to build natural comb structures, and leaving sufficient honey for them during winter. Beekeepers can avoid synthetic chemicals for disease and pest control, opting instead for organic methods where possible. Such practices, combined with environmental stewardship, aim to create a more resilient and thriving environment for bees within agricultural landscapes.