Bees are fundamental to ecosystems and agriculture, pollinating many food crops and contributing billions annually to the global economy. Despite their importance, bee populations face numerous threats, including various insect species that directly prey on them or infest their colonies, leading to decline. Understanding these threats is essential for protecting bee health and global food security.
Insects That Directly Prey on Bees
Hornets, such as the Asian Giant Hornet (Vespa mandarinia) and European Hornet (Vespa crabro), are formidable predators. Asian Giant Hornets can decimate European honey bee hives within hours; as few as 20 hornets can annihilate 30,000 bees. They employ a “hunting phase” where scouts capture bees outside the hive, decapitate them, and carry the thoraxes back to their nests as protein for their young.
The “slaughter phase” follows, where numerous hornets, guided by pheromone markings, descend upon a colony, killing all adult worker bees. After eliminating the adult bees, hornets occupy the hive to take pupae and larvae to feed their offspring. European Hornets, while predatory, typically hunt individually, capturing bees in the field or at the hive entrance. Yellowjackets (Vespula species) are aggressive predators that can devastate bee colonies. They locate hives by scent and attack to consume honey, pollen, and bee brood, often leading to colony disarray or abandonment, especially in late summer when other food sources become scarce.
Robber flies (family Asilidae), also known as assassin flies, are ambush predators that snatch bees mid-flight. They inject paralyzing saliva and digestive enzymes into their prey, liquefying internal organs before consuming them. While generalist predators, some species specifically target bees. Praying mantises also lie in wait, camouflaged in foliage or flowers, to capture unsuspecting bees. These direct predators contribute to individual bee mortality, which can weaken a colony’s ability to forage and defend itself.
Pests That Destroy Bee Colonies
Beyond direct predation, other insects and mites damage bee colonies from within, often leading to widespread bee death or complete colony collapse. The Varroa mite (Varroa destructor) is a widespread parasite that attaches to adult bees and developing brood, feeding on their hemolymph (a bee’s blood). This parasitic feeding weakens individual bees, shortens their lifespan, and impairs their development, leading to weaker adults. Varroa mites also serve as vectors for harmful viruses, such as Deformed Wing Virus and Acute Bee Paralysis Virus, which compromise bee health and immune systems, making them highly susceptible to disease.
Tracheal mites (Acarapis woodi) are microscopic internal parasites that infest the breathing tubes of adult honey bees. These mites block the bees’ breathing tubes, reducing oxygen flow and shortening the lifespan of affected bees. Infested bees may exhibit symptoms like an inability to fly, disjointed wings, and dysentery, which weaken the colony and can lead to losses, particularly during colder months when bees cluster tightly.
Small hive beetles (Aethina tumida) are another destructive pest, particularly in regions outside their native sub-Saharan Africa. Adult beetles and their larvae consume honey, pollen, and bee brood, tunneling through and damaging the comb. The larvae defecate in the honey, causing it to ferment and become slimy with an odor similar to rotting oranges, rendering it unusable by bees and unsalable. Severe infestations can cause bees to abandon their hive entirely.
Wax moths, including the Greater Wax Moth (Galleria mellonella) and Lesser Wax Moth (Achroia grisella), primarily target weak or distressed colonies and stored combs. Their larvae, known as waxworms, burrow through beeswax combs, feeding on wax, pollen, and larval remains, leaving behind silken tunnels and fecal matter. This destruction compromises the comb’s structural integrity, ruins honey and pollen stores, and can lead to hive collapse if left unchecked. The presence of these pests weakens the colony’s health and resilience, contributing to bee mortality.