Bumblebees More Heavily Contaminated by Metals Than Honeybees, Study Finds

Bumblebees are far more susceptible to heavy metal contamination than honeybees, accumulating up to seven times more toxic metals in the pollen they collect, according to a new study. Researchers from the University of Cambridge found that metals like arsenic, cadmium, chromium, cobalt, lead, and tin were significantly more concentrated in pollen gathered by bumblebees compared to that collected by honeybees foraging in the same landscapes.

The study, published in 'Ecological Entomology,' revealed that not only the pollen but also the adult bumblebees themselves showed approximately three times higher concentrations of these heavy metals. This heightened exposure can severely impact their cognitive functions, including learning and memory, disrupt their ability to navigate and find food, reduce reproductive success, and negatively affect the development of their offspring.

Scientists suggest several factors contribute to this disparity. Bumblebees often nest underground or in leaf litter, increasing their contact with localized soil contaminants. Their smaller colony sizes, typically ranging from 50 to 500 individuals, make them more vulnerable to the loss of workers compared to honeybee colonies, which can house 30,000 to 60,000 bees.

Furthermore, foraging habits play a crucial role. Bumblebees tend to collect pollen from fewer plant species and closer to their nests, usually within a 1.5-kilometer radius. This concentrated foraging makes them more exposed to any contaminants present in specific plants or local areas. In contrast, honeybees forage more widely, often up to 10 kilometers away, and from a greater variety of plants, which dilutes the impact of any single contaminated source. Bumblebees' hairier bodies also make them more prone to collecting contaminated dust particles.