Feeding bees an antidote wrapped in pollen-like particles may save them from pesticide poisoning, according to research by scientists in the United States.
The pesticides sprayed on plants to control harmful insects are high on the list of the many challenges that pollinators like honeybees and bumblebees face. A specific group of insecticides, organophosphates, pose a major threat – they account for more than a third of global insecticide sales and are highly toxic to bees.
“We wanted to develop a pollinator detox strategy and we found that we could do it by incorporating it into their food,” said Minglin Ma, biomaterials engineer at Cornell University, who led the study.
Phosphotriesterases are enzymes that break down organophosphates and render them harmless. But they don’t work well in bees’ acidic digestive tract. Ma’s team developed a method to package the enzyme into particles that mimic pollen in size and shape and can survive in the bee’s gut to counteract the insecticide.
The 8 μm diameter particles are made up of calcium carbonate – chalk – and a gelatin additive that helps control their size. Calcium carbonate is both easy for bees to consume and easy and inexpensive to produce in large quantities. The acid scavenging ability of the salt protects the enzyme from acidic conditions. When pesticides are released from ingested pollen, they pass through the pores of the microparticles and are removed by the phosphotriesterase they contain.
The team fed microcolonies of 50 bumblebee pollen contaminated with the organophosphate insecticide malathion. Bumblebees given only the phosphotriesterase or a sugar syrup control all died after a few days. But the bees given the microparticle counterpart survived.
Ma says it should be easy to roll out the antidote-infused microparticles to quickly protect or rescue managed honeybee colonies. “It can be mixed with anything you feed the bees, a pollen patty or liquid syrup, and used as a dietary supplement,” he says. He and his colleagues have already started a company, Beemunity, to market the product.
However, Dave Goulson, an insect ecologist at the University of Sussex, UK, wonders how this strategy can be extended beyond managed hives to include wild bees, which are often a much more important role in pollination. “I’m a little doubtful how wild pollinators could be made to consume these particles,” he says. And he is concerned that the availability of an antidote could be seen as an excuse to be more liberal with malathion and other chemicals that are highly toxic to all life, including humans.
Ma says they haven’t found a way to use the antidote to help wild pollinators. The team is looking to see if they can use a flavor or other feed preference that will attract wild bees – while not attracting and treating the harmful insects that the pesticides are targeting. “If we could do that, it would be extremely powerful,” says Ma.