A widely used pesticide could be the reason why bumblebees across the country are apparently shrinking. Research from scientists in the UK reveals that a pyrethroid pesticide, which is commonly used on plants and flowering crops, stunts the growth of worker bumblebee larvae, causing them to hatch out reduced in size.
It is feared that smaller bees will be less effective at foraging for nectar and carrying out their vital task of distributing pollen.
The study tracked the growth of bee colonies over a four-month period, examining the pesticides’ impact across their entire lifecycle. Half of the bees were exposed to a pyrethroid while monitoring the size of the colonies as well as weighing individual insects on micro-scales.
Worker bees from colonies affected by the pesticides over a prolonged period grew less and were significantly smaller than unexposed bees.
“We already know that larger bumblebees are more effective at foraging,” commented Gemma Baron, one of the researchers from the School of Biological Sciences at Royal Holloway, University of London.
“Our result, revealing that this pesticide causes bees to hatch out at a smaller size, is of concern as the size of workers produced in the field is likely to be a key component of colony success, with smaller bees being less efficient at collecting nectar and pollen from flowers.”
