Bumblebees are constantly facing the threat of extinction, threatening the future of the Earth itself since they play an important role in pollination. A recent study found a new threat to the bumblebee: a common neonicotinoid pesticide aka thiamethoxam.
Thiamethoxam entered the market back in the early 2000s and all GM corn in the US has been treated with either clothianidin or thiamethoxam, which are both neonicotinoids. Not only corn is trreated, as many soybean crops in the US have been treated with thiamethoxam as well. This does not begin to cover the full list of crops tainted with this pesticide. Researchers have now found that this threatens the very survival of bumblebees.
Prof. Nigel Raine from the University of Guelph found that exposure to thiamethoxam lowers the odds of a bumblebee queen starting a colony by more than 25%. He explained, “Bumblebee queens that were exposed to the neonicotinoid were 26 per cent less likely to lay eggs to start a colony. A reduction this big in the ability of queens to start new colonies significantly increases the chances that wild populations could go extinct.”
The study by Gemma Baron, Vincent Jansen, and Mark Brown from Royal Holloway University of London looked at neonicotinoids because they are commonly linked to contributing to the loss of bees and are actually being prohibited by many countries, including Canada.
The scientists looked at the effects of exposing the queen bumblebees to thiamethoxam. They used post-hibernation conditions they would typically encounter in the spring. During this time they would be preparing to lay their first eggs and to start a colony.
Raine stated, “Given the vital role spring queens have in maintaining bumblebee populations, we decided to focus on assessing the impacts at this stage in the life cycle. These spring queens represent the next generation of bumblebee colonies.”
For the experiment itself, the researchers used a sample size of 300 queen bees. They introduced a range of environmental stressors including parasitic infections. Half the bees came out like they were supposed to. This group came from hibernation and were fed syrup treated with pesticide at levels typical of wild pollen and nectar. They were treated for 2 weeks.
After this 2 week period, the researchers recorded the egg laying behavior and mortality rates over a 10 week period.
Raine detailed the experiment by stating that they “observed the queens to see whether low level pesticide exposure might lead to changes in these important nesting behaviours.” He added, “When a queen is going to set up a colony, she will secrete wax and form it into containers for nectar and pollen. She will then begin to lay her eggs and sit on them like a bird.” Thus being the measured activity to detect any difference in behavior when exposed to the pesticide.
Overall, those exposed queens laid 25% less eggs than they typically would. This was a small sample and occurred over a short period of time, so through mathematical analysis, the researchers projected that exposure at this rate will threaten the extinction of the wild bumblebees.
In other words, thiamethoxam and possibly neonicotinoides as a whole may devastate entire populations of bumblebees. This would not be so bad had these pesticides not been so prominent for years in the corn and soybean fields that the bumblebees pollinate.