Pesticides can impair the behaviour of bumble bees and affect their ability to eat and rear their young, a new study has shown.
The research, which allowed humans to take a closer look at the bee in its environment, revealed how the pesticide neonicotinoid can harm its behaviour.
Neonicotinoids are a class of insecticides chemically similar to nicotine. The most commonly used to control weeds and pests are Bayer and Ortho products.
The findings add to a long-standing list of concerns about these critical pollinators for that pollinate 70 of the around 100 crop species that feed 90 per cent of the world.
The study was published in Science journal and compared the behaviour of bees exposed to pesticides and bees who weren’t.
Researchers placed cameras inside 12 specially made boxes that contained one chamber for a nest and another chamber for foraging.
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The United Nations has warned that 40 percent of the planet’s insect pollinators risk global extinction, which would have serious implications for food production and ecosystem health
Some bees were exposed to concentrations of the neonicotinoid imidacloprid similar to that expected in the environment. Others were not.
What they found confirmed what environmentalists had been warning for years; that pesticides are killing bees and threatening our livelihoods.
The pesticide-exposed bees were less social in a variety of ways than bees not fed nectar that contained neonicotinoids.
‘Exposure to the neurotoxic pesticide resulted in measurable changes in worker bee behaviour within the nest,’ said the report.
‘The workers were less active, less likely to feed and care for larvae, and more likely to be found towards the periphery of the nest.’
However, the effects were particularly apparent at night, the bees showed further signs of inactivity.
‘Bees actually have a very strong circadian rhythm,’ said Dr James Crall, a postdoctoral fellow at Harvard University.
‘So what we found was that, during the day, there was no statistically observable effect, but at night, we could see that they were crashing.’=
Some of the bees used in the study were exposed to concentrations of the neonicotinoid while others were not. The pesticide-exposed bees were less social, less active and less likely to feed and care for larvae
Experiments also showed that pesticide exposure made it more difficult for bees to regulate their body temperature, and to build a protective wax cap over the colony.
‘Almost all of our control colonies built that cap,’ Dr Crall said.
‘And it seems to be totally wiped out in the pesticide-exposed colonies, so they lose this capacity to do this functional restructuring of the nest.’
Their findings add to mounting evidence of the harm posed by neonicotinoid pesticides.
The United Nations has warned that 40 per cent of the planet’s insect pollinators, particularly bees and butterflies, risk global extinction, which would have serious implications for food production and ecosystem health.
The European Union states have voted against the use of three neonicotinoids – clothianidin, imidacloprid and thiamethoxam – in crop fields.
Say EU states have voted against their use, and explain where else in the world they are routinely used in farming
France has gone even further and banned these three neonicotinoids plus thiacloprid and acetamiprid, both outdoors and in greenhouses.
In recent years, bees have been mysteriously dying off from ‘colony collapse disorder,’ blamed partly on pesticides as well as mites, viruses, and fungi.
WHAT HAS HAPPENED TO THE BEES?
Declines in recent months to honey bee numbers and health caused global concern due to the insects’ critical role as a major pollinator.
Bee health has been closely watched in recent years as nutritional sources available to honey bees have declined and contamination from pesticides has increased.
In animal model studies, the researchers found that combined exposure to pesticide and poor nutrition decreased bee health.
Bees use sugar to fuel flights and work inside the nest, but pesticides decrease their hemolymph (‘bee blood’) sugar levels and therefore cut their energy stores.
When pesticides are combined with limited food supplies, bees lack the energy to function, causing survival rates to plummet.