We have no idea if pesticide protections for bees actually work — a serious issue for conservation

Pesticides are slowly wiping bees off the face of the Earth, yet scientists are still unable to come up with evidence-based ways to protect them. That isn’t for a lack of trying — many different tactics are being trialed, but widespread success remains elusive. And this problem is severe, given that many of our agricultural food products — from apples to pumpkins to cucumbers — rely on pollinators like bees. Losing bees could trigger mass starvation throughout the world, to say nothing of the devastating effect such a casualty would have on global ecosystems.

In a recent report in the Journal of Economic Entomology, Edward Straw and Dara Stanley, both researchers at University College Dublin, analyzed as many studies as they could find about whether bees are adequately protected from pesticides. They focused specifically on mitigation measures, or actions followed by pesticide users to limit how much of the chemicals reach unintended targets.

The study includes a chart of mitigation methods that have at least been tested through published studies, regardless of their quality. At first glance, only one category of mitigation measure appeared to be thoroughly covered: repellents, or techniques used to repel bees from visiting crops recently treated with pesticides. While other strategies like alternative food sources or killing weeds to discourage bees from feeding nearby had only been tested in seven or fewer published studies, there were 12 published studies on repellent chemicals that could presumably reduce exposure. A dozen studies seemed to be a lot — right?

“Yeah, no, not even close!” Straw, a post-doctoral researcher at University College Dublin, replied. “All of those 12 measures on testing repellents have been done on honeybees!”

In other words, the studies had limited usefulness because they were only tested on two species of honeybee. However, there are more than 20,000 different species of bee worldwide. What make work for honeybees (Apis mellifera) may not work for bumblebees or solitary bees, let alone other types of insects.

This speaks to the broader problem with the research on how pesticides impact bee populations. As the authors explain, the research on mitigation measures overwhelmingly focuses on managed bees, i.e. honeybees, thereby neglecting wild bee populations. Additionally they found that are few empirical tests on the most widely-used mitigation measures, namely those that are recommended on pesticide labels. As a consequence, the authors “recommend that more, and stronger, scientific evidence is required to justify existing mitigation measures to help reduce the impacts of pesticides on bees while maintaining crop protection.”

Simply put, we have almost no idea if our strategies to protect bees are working. Yet what counts as “enough” in terms of research? As Straw explained to Salon, it is not “healthy” to look at the matter simply in terms of the number of studies. The quality of the research is also important.

“If you want evidence that a measure works, you want evidence from multiple continents, where you have different sorts of cropping systems and you want evidence from multiple species,” Straw said. “You really want to be covering honeybees in good depth because they’re quite easy to work with, bumblebees in good depth because they’re quite easy to work with in Europe and America. And then some work, at least some work, on a few different species of solitary bee. So you need those broad categories there.”

Additionally, Straw argued that studies need to examine not just pesticides “very broadly,” but also specifically investigate subcategories like insecticides, fungicides and herbicides. “To loosely guess, you’d be talking about somewhere in the region of 20 different papers of quality science for us to say, ‘Okay, let’s actually think that this measure probably has a good basis of support.'”

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He added, “You would need a handful, five or six, of genuinely good papers to say actually yes, we can tick the bare basic boxes of saying we have evidence-based policy here.” 

The next question is why honeybees seem to receive disproportionate attention from published scientists. 

“Honeybees, in all aspects, are the best research bee species,” Straw said. “They have a long, long relationship as a species with us. We’ve been domesticating them and culturing them and taking products from them, like honey, for thousands of years. We have very established ways of working with them and we have a very established basis in science on how they exist, how they work, what things impact them.”

Beyond that, modern pesticides have not even existed for a full century, but only trace back to the 1940s. That is why the thinking, not just among business leaders but also among environmentally-minded scientists, can be limited.

“We want great pesticides [so we ask] ‘How do they impact bees?’ ‘Let’s look at honeybees.’ ‘That makes sense.'” Straw imagined the hypothetical conversation going. “As time has gone on, we’ve developed [studies with] other bee species and we’ve come to be able to test them, but they are harder to test in quite a few ways because they can be more expensive.”

Although bumblebees may be affordable for some, “they are a little bit harder to work with,” Straw said. “Solitary bees are a nightmare to work with. If you want to get them to feed on stuff, you really, really have to work. That’s just to make them engage in your experiments.”

Straw admitted that his passion for bees is based on more than their importance to humans, whether as helpers or hinderers of agriculture. As he described it, he was working in the Irish canola fields with buff tailed bumblebees, or Bombus terrestris. 

“It was really enjoyable being out in that field. I was surrounded by like a sea of yellow flowers and it was really pretty walking through the tram lines where the tractor had driven and collecting those bees,” Straw recalled, noting how the various insects he encountered had wildly different personalities.

“Some insects flew away and some insects and some bees didn’t really care about me,” Straw remembered. “You could tell which was which because the bees have self-defense mechanisms. They can sting you. So they don’t really care if you are in their way because they’ll just do their own little thing.” As he described it, “bees are lovely. I think they’re really fun to work with.” Yet he also admitted that he has his own preference among bee species — for bumblebees.

“I’m really bad at identifying them, which is why I work on bumblebees. In Ireland there are only 21 species of bumblebees,” Straw explained. “It’s not that hard to work with because you could tell mostly which ones are which!”