"Bees actually have a very strong circadian rhythm," lead author James Crall explained in a statement. "So what we found was that, during the day, there was no statistically observable effect, but at night, we could see that they were crashing. We don't know yet whether (the pesticides) are disrupting circadian gene regulation or if this is just some, maybe physiological feedback... but it suggests that, just from a practical perspective, if we want to understand or study these compounds, looking at effects overnight matters a lot."
A drop in activity is problematic as active bees help maintain the temperature of the nest by fanning their wings and vibrating their body muscles – something that’s key to the development of healthy larvae.
What’s more, the control bees built a “wax cap” to insulate the colony, but the bees exposed to the pesticide failed to do this. The bees also tended to stay further from the center of the nest (where their brood was), suggesting that they were spending less time caring for the colony’s offspring.
There are thousands of species of bee, and both solitary bees and those that live in small colonies like bumblebees are probably more vulnerable to the pesticides than honeybees, which live in vast hives.
The new findings are worrying as bees are important pollinators, both of wild plants and the crops we rely on for food. Luckily, governments are waking up to the issue of neonicotinoids, with the EU currently banning three types. Just recently, France introduced the world’s toughest ban on the chemicals. Let’s hope other nations follow suit.