Pesticides are knocking bees off balance

Dwindling bee populations are being exposed to chemicals that can have dangerous effects on their eyesight
18 August 2022

Interview with 

Rachel Parkinson, University of Oxford


A honeybee


There has been a lot of buzz in the last few years around protecting bees. Their pollination contributes to one third of the world’s food production, but their numbers have seen a dramatic decline in the past few decades. The reasons behind this include climate change, habitat loss, disease and also pesticides, with a new study hoping to highlight just how some pesticides may be seriously harming a bee’s eyesight. Rachel Parkinson, of the University of Oxford, devised an experiment to determine the effects of pesticides on a bee’s ‘optomotor response’, which re-orients a bee that has been blown off course. She has been speaking to Will Tingle about how bees react to these chemicals, and how we might help our flying friends.

Rachel - Primarily the effects that I saw were that the bees, although otherwise they seemed fine, they were moving around in a very kind of normal way in their cage. When I put them on this air supported ball for them to respond to the moving gradings, they were not able to turn accurately in order to follow the direction of motion. So their ability to perform this reflex-like behaviour was really diminished, was really impaired.

Will - What are the ramifications for this sudden impairment on their visual acuity, in relation to how they would go about their daily lives?

Rachel - Right, so this reflex is crucial so that these insects are able to maintain a steady heading. As a teeny tiny insect, it happens very often that there could come along a gust of wind that blows you off course, and you need to be able to very quickly right yourself in order to know where you are in the world. And so if the ability to properly orient themselves is lost, then it's quite likely that there would be other effects on their ability to navigate.

Will - Where are these pesticides most commonly found?

Rachel - So these pesticides are very commonly included in seed treatment mixtures. So what that means is that they're actually treating the seeds of various agricultural crops with pesticides prior to planting them. And then what happens is the pesticides become incorporated into all parts of the plant. So Sulfoxaflor is a very new pesticide. It's only been in commercial use for a few years. And already we have seen a variety of effects that this insecticide is having on different animals that interact with these crops.

Will - And I assume that this is not specific to bees as well. There are other insects that are having similar issues.

Rachel - Yeah, well, you know the purpose of pesticides is to kill insects. That's what they're designed to do. And unfortunately they're generally not specific to a particular type of insect. As it turns out, bees tend to be especially vulnerable when it comes to a lot of insecticides because they just don't have the same detoxification machinery in their body to deal with them.

Will - So if these pesticides cannot really distinguish between friend or foe, are there any ecologically friendly alternatives that we could perhaps use?

Rachel - Yeah, that's a really complicated topic and I'm hesitant to sort of go down the path of 'let's just ban all pesticides' because of course we need agriculture and we need it to function in this way in order to feed the world. Um, so there needs to be very high output. I would hope that there's a way that we can maybe rethink the way pesticides are used, maybe less so prophylactically, so less so as a preventative measure like treating an entire field with insecticides before there's any pests present. Perhaps trying more to treat only when necessary. But again, it's a very complicated, a very complicated problem.

Will - If the subject of pesticides is so nuanced, are there alternative ways we can reduce bees and other insects' exposure towards pesticides?

Rachel - You know in nature, there are many natural pest control methods, including birds and maybe other types of insects that, if they were allowed to thrive in these environments, that perhaps there would be a more natural way to manage pests. Also even in the realm of pesticide use, trying to find different options that are going to be specific to the pests that we're trying to eliminate, rather than these sort of generalist insecticides.


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