Researchers from Royal Holloway University of London reported that neonicotinoid pesticide reduces the number of new queens and males in bumble bee colonies.
The recently developed neonicotinoid pesticide was hailed as a potential replacement for the contact pesticides. The neonicotinoid pesticides block receptors in the insects’ brains that leads to paralysis and kills the insects. Although the pesticides is not lethal to larger creatures and even bees in smaller doses, the pesticide disturbs the ability of bees to navigate, find food, reproduce, and form new colonies. Although the European Union banned the outdoor use of five neonicotinoid pesticides in April, 2018 and Canada declared the ban on August 15, 2018, the pesticide is used widely in the U.S.
Resistance to neonicotinoids was observed in several insects in recent years, which led to development of alternative such as sulfoximine— a group of neonicotinoid-related chemicals. Sulfoximine dodges the enzymes that offer insects some resistance along with blocking of the same class of receptors in the insect brain. The new variant was approved for use in China, Canada, and Australia. However, a French court suspended licensing for two sulfoximine-containing products in 2017, owing to environmental concerns including potential toxic effects on bees.
The researchers fed bumble bees, sugar laced with sulfoxaflor to investigate sulfoximine’s effects on bumble bee colonies. Sulfoxaflor is the first sulfoximine-based pesticide in the market. The U.S. Environmental Protection Agency measured the concentration of the pesticide as dosing of such pesticides is one of the most controversial aspects of pesticide studies. The researchers released the colonies of bees into the field after 2 weeks. It was observed that the colonies fed with pesticide produced fewer worker bees between 2 and 3 weeks after exposure than control colonies that received only sugar. This period is the time required for bumble bee larvae to reach adulthood. The exposed colonies produced 54% fewer new queens and males after 9 weeks. The findings that reported adverse impacts sulfoximine on the reproductive system in bumble bees was published in Nature on August 15, 2018.