Honeybees eat protein-rich plant pollen. Some will steal from other bees for it.
Pollen theft has occurred throughout the US. Italian researchers have also seen honeybees steal pollen from bumblebees. Bee-on-bee theft is seldom documented as extensively as in the December 21 Apidologie observations.
Independent naturalists Tiziano Londei and Giuliana Marzi, both from Milan, captured footage of honeybees (Apis mellifera) trying to push bumblebees off a woolly thistle flower in Mount Antola, Liguria, in summer 2019. A deeper glance at the footage showed that this was a robbery, not competitive harassment.
As red-tailed bumblebees (Bombus lapidarius) searched flowers for nectar and pollen, pollen grains clung to their hairy bodies (SN: 9/6/17). Londei and Marzi saw honeybees blatantly steal pollen. Male bumblebees were less affected by the theft, thus robbers targeted them more than females.
“Honeybees are well-known as pollen pigs,” says Missouri State University in Springfield scientist Avery Russell, who was not involved in the research. He believes taking bumblebee pollen “doesn’t seem like a far stretch.”
The researchers returned again in three years and monitored bees at two different places 25 km distant to see how widespread the crime is. Honeybees at these other locations did not steal from bumblebees, but those at the first site did year after year. The researchers found that honeybees harvested pollen from three of 31 flowers in 2021 but took from 28 of 66 bumblebees.
After examining these places, the researchers believe honeybees steal pollen from blooms like the woolly thistle but where there are many more bees.
Honeybees have only stolen pollen in North America, initially in Kansas and subsequently in California and Indiana. Observing the behaviour in Italy shows a worldwide crime wave. Russell wants to know whether pollen stealing harms bumblebees or the flowers they pollinate. He also wonders whether other bees take pollen. He notes that bumblebees bite one other’s pollen baskets in the hive.