Agriculture currently faces a huge conundrum: pesticides kill the pests that would damage or destroy our crops, but these pesticides are killing the very pollinators that make agriculture possible. Recently, it has been discovered that the widely used neonicotinoid pesticides cause bee population declines. After much debate, three of these pesticides are now banned in Europe and two will be phased out in Canada. The question of how to safely protect these crops against pests still remains. A new class of pesticides based on sulfoximine is being suggested as an alternative. However, a new study published in the journal Nature has just reported that these pesticides could be just as harmful as the ones that they are replacing.

Bee reproduction affected

Bumblebees were exposed to low doses of the new pesticide in the lab (similar to what they would be exposed to in an agricultural field) and transferred to a field. Their reproductive output was severely compromised: fewer workers and only half as many reproductive male bumblebees were produced. This is a drastic impact and would affect wild bumblebee population immediately if put into widespread use.

Besides being useful at pollinating, bumblebees are pretty darn cute. Image credits: Pixabay.

“This study shows an unacceptable scale of impact on bumblebee reproductive success, after realistic levels of exposure to sulfoxaflor,” commented Lynn Dicks, a Natural Environmental Research Council Fellow at the University of East Anglia.

Bigger picture

From the results of this experiment, the new sulfoximine-based pesticide is not a viable alternative for currently used pesticides. The study also highlights the importance of conducting these sorts of studies before approving a pesticide for widespread use. Indeed, two sulfoxaflor-based pesticides were already approved by the US Environmental Protection Agency in 2013; many other countries have also registered this pesticide for use. Hopefully this study will convince the prohibition of this pesticide as well; after all, using a pesticide that harms bees is self-sabotage in the long run.

It is a tricky situation and there aren’t any magic solutions at the moment. Most arthropods have such conserved systems that it is difficult to selectively target only a group of them. If a pesticide is harmful to a pesky group of arthropods, it is usually also harmful to other useful ones, such as pollinators and stream invertebrates. Other pollinator-friendly alternatives to protect crops need to be explored immediately.

Journal reference: Harry Siviter et al. Sulfoxaflor exposure reduces bumblebee reproductive success, Nature (2018). DOI: 10.1038/s41586-018-0430-6