Common pesticide linked to concerns over bee size

BUMBLEBEES COULD be shrinking because of exposure to a widely used pesticide, a study suggests.

Experts fear smaller bees will be less effective at foraging for nectar and carrying out their vital task of distributing pollen.

Scientists in the UK conducted laboratory tests which showed how a pyrethroid pesticide stunted the growth of worker bumblebee larvae, causing them to hatch out reduced in size.

University of London researcher Gemma Baron from the School of Biological Sciences at Royal Holloway said: “We already know that larger bumblebees are more effective at foraging.

“Our result, revealing that this pesticide causes bees to hatch 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.”

Pyrethroid pesticides are used on flowering crops to prevent insect damage.

The study, the first to examine the pesticide’s impact across the lifecycle of bumblebees, tracked the growth of bee colonies over a four-month period.

Researchers exposed half the bees to a pyrethroid while monitoring the size of the colonies as well as weighing individual insects on micro-scales.

They found that worker bees from colonies affected by the pesticides over a prolonged period grew less and were significantly smaller than unexposed bees.

A Europe-wide moratorium on the use of three neonicotinoid pesticides, which was brought in because of their alleged harmful effect on bees, has seen a rise in the use of pesticides like pyrethroids, which is likely to continue say the researchers.

Dr Nigel Raine said: “Further studies needs to be a priority for scientists and governments.”