Insecticides Could Be Making Bees Less Curious

Neonicotinoid insecticides, which are the most widely used insecticides in the world, have been linked with declining populations of bees. As pollinators, bees play a critical role in ecological networks, so their loss can lead to serious knock-on effects for a wide variety of plants, and for the animals that rely on those plants for food. That includes us. Bees pollinate around a third of the plants central to the human diet, including many fruits and vegetables. While we’re at it, coffee and chocolate production also depend on healthy bee populations.

The exact mechanism by which neonicotinoid insecticides contribute to diminishing bee populations isn’t well understood. After all, the levels of neonicotinoids often used in agriculture are not immediately lethal to bees when first encountered. In other words, they don’t suddenly and dramatically die mid-air. It’s more pernicious than that. Increasing evidence shows that neonicotinoids can accumulate in individual bees and negatively effect a suite of functions including memory, flight and the ability to efficiently collect pollen. This, in turn, can be disastrous for the colony.

For example, several months ago, researchers discovered that neonicotinoid pesticides appear to impair bumblebees’ ability to vibrate during pollen collection and reduce the number of pollen grains they can collect.

Penelope Whitehorn at the University of Sterling in the UK and her colleagues had been studying a type of pollination mechanism that bumblebees employ, called ‘buzz pollination’. During buzz pollination, bees vibrate their flight muscles at high frequencies — in the area of 400 vibrations per second — which helps them loosen and remove sticky pollen from flowers.

Buzz pollination is a tricky skill though, and bumblebees go through what appears to be a learning process while they get the hang of it. Normally, they improve with experience.