A new study conducted by the Royal Holloway College of London suggests that the use of thiamethoxam as a pesticide in the UK could have a debilitating effect on the life cycles of wild bumblebees.
The report was published in the Proceedings of the Royal Society B and tested four different species of wild bumblebees by exposing them to similar amounts of thiamethoxam as they would experience in nature. The results indicated that egg development in the bumblebee queens was lessened as a direct consequence of the insecticide.
What is thiamethoxam?
Thiamethoxam is a neonicotinoid insecticide most commonly used by farmers to control pests and limit damage among their agricultural yield. For example, many pesticides are sprayed by farmers in order to combat blight and eliminate worms and other pests in a variety of fruit and vegetables.
Unfortunately, substances such as thiamethoxam are indiscriminate in the damage they wreak on the insect world. A recent decline in the global bee population has led to concerns that the substance may be having detrimental effects on their health and lifestyle. In turn, this has prompted the EU to impose a ban upon the use of the substance in all member states.
This latest study adds further fuel to the challenges facing the pesticide industry, by indicating that the neonicotinoid could be impacting the appetites of some species tested and the ovary development of all of them.
Reduced fertility rates in queen bees
The study captured four bumblebee queens from different species during springtime and exposed them to levels of thiamethoxam representative of those occurring in the wild for a period of two weeks.
At this point, two of the four species tested showed a smaller appetite for artificial nectar, while all four demonstrated reduced fertility rates. By inadvertently ingesting the toxins in springtime during their feeding cycle, this could have an adverse effect on their ability to reproduce later in the year.
This is because females rely heavily on having gorged themselves on nectar and pollen during the spring and summer to build up stores of fat, so that they can successfully hibernate in the colder months. Furthermore, reduced fertility rates lead to less workers and less queens, which ultimately results in a decline in international bee populations.
Save the bees!
Bees are essential organisms to our ecosystem for the cross-pollination services they provide. A reduced number of bees leads to less diversity in the flora of the national and international countryside, which in turn has an effect on the other species which rely on that flora as its food source and habitat.
Over recent years, the number of bees worldwide has been in decline due to a variety of different reasons. Climate change has interrupted their life cycles and feeding and mating habits, as well as contributing to a loss of habitat. Meanwhile, pathogens and insecticides such as thiamethoxam have jeopardised their continued existence even further.
With that in mind, Professor Mark Brown of Royal Holloway College has called for further research to be undertaken so that the harmful effects of pesticides like thiamethoxam can be fully determined.
“Future studies across different species are likely to demonstrate further variation in the impact of neonicotinoids, and conducting such studies needs to be a priority for scientists and governments,”explained Professor Brown, who contributed to the study.
