Pesticides May Cause Queen Bumblebees To Lay Fewer Eggs


Bumblebees are major pollinators for agriculture, but there are still gaps in our knowledge regarding how pesticides affect them. TwilightArtPictures/Shutterstock

Although there was good news in regards to American honeybees this past week, unfortunately that's just one piece of the picture. A new paper has found that a common pesticide may be having devastating effects on the common bumblebee, preventing them from forming new colonies and potentially contributing to their local extinction.

Much research has looked into the impact that neonicotinoids, a particularly prevalent pesticide, have on honeybees (Apis mellifera). As a major pollinator of our crops, this is obviously concerning, but A. mellifera is just one species of bee out of tens of thousands of bee species and hundreds of thousands of insect pollinator species. This means it is vital that we fully understand how these chemicals impact the wider ecology.


In light of this, the researchers investigated how one specific neonicotinoid pesticide, thiamethoxam, impacts the buff-tailed bumblebee (Bombus terrestris). As one of the most common bumblebee species in Europe, they too play a significant role in the pollination of our crops, and as eusocial insects, they form much smaller colonies than the more gregarious honeybee. 

For the study, published in Nature Ecology & Evolution, the researchers particularly wanted to see how thiamethoxam affected bumblebee queens. In a laboratory setting, they exposed the queens to levels of the pesticide that they encounter in the wild. Overall, they found that exposure to the chemicals caused a 26 percent reduction in the proportion of queens that laid eggs.

From this, they were then able to calculate the chance that colony collapse would occur, which came out at around 28 percent. If this were to happne, it would have a massive impact on the survival rates of bumblebee colonies. “This showed that the impacts of neonicotinoids on colony founding – by itself – significantly increases the risk of an exposed bumblebee population going extinct,” explains study co-author Mark Brown in a statement.

Brown says that most studies have not looked at how the pesticides impact colony foundation, with many instead focusing on the impact for individual bees. “As successful colony founding is key to the size of bumblebee populations, and bumblebee queens feed on crops and plants that can be contaminated by neonicotinoids, this life-cycle stage could be key in understanding the impacts of neonicotinoids,” continues Brown.


Due to growing evidence, there is currently a moratorium on the use of neonicotinoid pesticides in the European Union until further review of their impact on pollinators. This means that any new research on the topic is an important addition to our understanding of these chemicals.

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