Pesticide exposure in bumblebees harms pollination study reveals

Bees range from solitary, independent individuals to highly dependent members of complex social structures.

The study involved assembling three groups of bumblebee colonies and exposing two of them to two different levels of the commonly used pesticide thiamethoxam-2.4PPB and 10PPB and then allowing them to pollinate segregated apple trees.

Bumblebees pollinating apple trees that become exposed to neonicotinoid pesticides demonstrate a decrease in their ability to pollinate the trees effectively.

However, other researchers who have been extensively researching the topic have said that while the honeybees have been able to at least hold off the most severe of die-offs, other pollenating insects are not so effective. In this new effort, the researchers looked instead on the possible impact on pollination by bees exposed to one type of pesticide, instead of the impact on the bees themselves.

The researchers encouraged this last issue to be explored along with colony performance metrics using large colony monitoring datasets. In another study, researchers from the Lund University found the bumblebee colonies in areas treated with neonicotinoids stopped growing.

The bees collected pollen from apple trees less often and visited flowers less frequently than when they were not exposed to neonicotinoid pesticides, scientists said. However, the colony as a whole has ways of recovering.

More information: Dara A. Stanley et al.

Nicotine-like pesticides are likely to cause long-term damage to wild honey bee populations even though they might initially appear to be harmless, a new study has shown. Here we show the first evidence to our knowledge that pesticide exposure can reduce the pollination services bumblebees deliver to apples, a crop of global economic importance.

In essence, this means male bees are born during foraging periods, and this delayed drone production might “somehow disrupt this biological synchrony, and should therefore be addressed in terms of mating success or fitness value of reared drones”.

“If exposure to pesticides alters pollination services to apple crops, it is likely that these other bee-pollinated crops would also be affected”. Studies have found that pesticides have a negative impact on bee reproduction and behavior. How the regulations turn out will affect growers’ fates as neonics are present in around 30% of insecticide use worldwide.