Bumblebees Shrinking Pesticide
January 20, 2014

Pesticides Causing Bumblebees To Shrink, Creating Less Efficient Colonies

Lee Rannals for redOrbit.com - Your Universe Online

According to a study published in the Journal of Applied Ecology, pesticides could be causing worker bees to shrink. A study by researchers from the Royal Holloway University of London found that exposure to pesticides causes worker bumblebees to grow less and hatch at a smaller size. The team found that prolonged exposure to a pyrethroid pesticide reduces the size of individual bees produced by a colony.

The team researched colonies of bumblebees in their laboratory and exposed half of them to the pesticide, which is used on flowering crops to prevent insects from damaging them. The scientists kept track of how the bee colonies were growing over a four-month period, recording their size and weight on micro-scales. They also monitored the number of queens and male bees produced by the colonies.

"We already know that larger bumblebees are more effective at foraging. Our result, revealing that this pesticide causes bees to hatch out at a smaller size, is of concern as the size of workers produced in the field is likely to be a key component of colony success, with smaller bees being less efficient at collecting nectar and pollen from flowers," said researcher Gemma Baron from Royal Holloway.

The bumblebee population has been declining around the world over the past decade, and researchers are trying to pinpoint what the cause has been for the collapse. Pesticides have been proven to be the main culprit by a few studies, and finding alternative methods for farmers has become an increasingly urgent concern for researchers. This was the first study to examine the impact of pyrethroid pesticides across the entire lifecycle of bumblebees.

"Bumblebees are essential to our food chain so it's critical we understand how wild bees might be impacted by the chemicals we are putting into the environment. We know we have to protect plants from insect damage but we need to find a balance and ensure we are not harming our bees in the process,” said Mark Brown, professor at the university.

The European Union has banned the use of three neonicotinoid pesticides, so farmers are having to find alternative pesticides to use. Studies like these will open up a flow of intel about these and other pesticides and how they might impact the bumblebee population as well.

"Our work provides a significant step forward in understanding the detrimental impact of pesticides other than neonicotinoids on wild bees. Further studies using colonies placed in the field are essential to understand the full impacts, and conducting such studies needs to be a priority for scientists and governments,” said Dr Nigel Raine.