Science was not nowadays, it gives us a huge amount of good news. We will accelerate towards a climate disaster. We've ruined the environment so much that it's hard to even call it an environment. And this comes back to bite us (or sting): Populations of bees we rely on to pollinate our crops are falling.
But learning also comes to the rescue by sticking QR codes to the back of bumblebees and tracking their movements using a robotized camera. Researchers have created a system that tracks individual bees, as well as the dynamics of entire colonies exposed to imidacloprid, a neurotoxin that belongs to the infamous group of neonicotinoids of pesticides. The findings are not pretty, but they can go a long way, trying to figure out how neonicotinoids destroy bees and how we can save these leaflets.
Neonicotinoids are the most common class of insecticides in the world. "When we first used them in agriculture for the first time, they passed the initial tests: Oh, are they safe for bees in concentrations that they might encounter in the field?", Says a Harvard biologist James Crall, author of paper in Science describing the technique of bumblebees tracking.
But these tests were not accurate enough. "You may not see a dead bee in 24 or 48 hours, but you still see important changes in behavior over time that lead to colony and growth dysfunction in the long run," Crall adds.
Even if a neonicotinoid, such as imidacloprid, a common insecticide, does not kill the bees, it can cause other changes. Previous studies show, for example, that neonicotinoids in the field can weaken the ability of bees to move around and find flowers. This has an effect on how the bee feed is to be fed and their colonies. What's happening inside a colony exposed to neonicotinoids is more difficult to analyze.
That's where Crall and his team study. In the laboratory, they established a dozen colonies of bumblebees, each of them housed in a transparent acrylic box. Researchers fed some colonies with imidacloprid at levels equal to those that would be exposed to the field, while other control colonies would be free of imidacloprid. A robotic camera system rotates on tracks overhead, looking into each slot below. "So we monitor for about 5 minutes what happens in each colony 12 times a day," says Crall. "And we can run it fully autonomously for almost two weeks." Because each bee has a QR code on its back, the computer vision system can track their movements day and night.
The differences that scientists have found between discovered and normal colonies are striking. "Bees are less active, so they spend more time resting," says Crall. "They are a little further from the center of the nests," where the larvae require care ", and also less cooperate with the companions in the nest." And behavioral changes are more visible at night. "Sometimes a colony in the eye seems perfectly functional during the day, and then you see these powerful accidents overnight."
Lower levels of activity are particularly problematic when one considers that the larvae have these larvae to be dispersed. Healthy bees will actively warm the young with their body by vibrating their muscles. What Crall and his colleagues found that colonies exposed to imidacloprid are not as good at keeping the temperature of larvae as normal bouquets that can affect younger growth.
"If this is one of the main ways in which these compounds affect growth, it may be more extreme in some environments than others, or in different conditions than others," says Crall. If the outdoor temperature is beautiful for bumblebees, it may not be a big deal. But if you have temperature fluctuations and imidacloprid affects the ability of the individual to control the climate of the nest, the young may not develop.
This was not the only difference in the way bees care their little children. Usually, bumblebees build a wax canopy that sits like a blanket on the developing brood again for warmth. Almost all control colonies with which Crall experimented did this, but none of the colonies were exposed to imidacloprid. "This probably disturbs not only these direct short-term behaviors, but these long-term changes in nest architecture," says Crall.
Most bee species are, however, lonely and not social. What happens to lone bees exposed to neonicotinoids? Females are largely lonely in these species: they connect with a man and the male will start. "Then this woman has to do all the different activities involved in nesting, feeding, laying eggs and continuing this cycle for weeks, and in some cases months, until she dies," says Nigel Raine of the University of Guelph, who researches bees and exposure to pesticides and who wrote a comment for this new study. "Therefore, we can imagine that exposure to pesticides for this person may have more serious consequences for their reproductive ability."
At the other end of the spectrum there are honey bees whose colonies count in thousands. (The species that investigates Crall is in the middle: a bumblebee Bombus impatiensfrom about 200 to colonies.) Neonicotinoids cause subtle behavioral changes also for honeybees, but this may not be as serious as it would be in the case of a small colony of bumblebees or lonely bees. "A relatively small impact on the results of the preying unit can be masked by a larger number of people leaving and performing this task," says Raine.
Good news for honey bees, but here lies the problem. Researchers and regulators rely heavily on honeybees as a model to study exposure to neonicotinoid – it's easy to find them, for example. But when it comes to pesticides, what happens in the case of honey bees probably does not depend on the hustle and bustle of bees because of the size of the population. Raine says he works with colleagues and regulators to take into account these potentially more sensitive species.
In addition, we are talking about one stressor here: Crall and his colleagues analyzed only one pesticide from seven neonicotinoids. But the idea is that scientists can use this technique to subject other pesticides to tests in bee colonies.
Bees are in trouble, yes. But thanks to innovative techniques, such as this one, scientists better understand what is a threat to them. Maybe some good news on a crazy planet.
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