Insecticides come in different types. More than a third of all types sold worldwide consist of organophosphates, of which malathion and parathion are the most commonly used. They are intended to neutralize pests, but can also be deadly to bumblebees and bees.

It is known from previous research that phosphotriesterases, enzymes containing metal ions, can break down the organophosphates. It is used in highly polluted soils. To see whether the enzymes also have a detoxifying effect for pollinators, the American scientists decided to conduct an experiment with Bombus impatiens, a species of bumblebee commonly found in the US. 

Pure sugar water

The bumblebees were first poisoned with malathion and then fed either “loose” phosphotriesterases dissolved in sugar water, or enzymes packaged in calcium carbonate to make them resemble pollen grains. There was also a control group with bumblebees that were given only sugar water. In the group with loose enzymes and the group with pure sugar water, all bumblebees died. But in the group with the fake pollen, all the bumblebees survived. 

The advantage of the calcium carbonate shells is that the enzymes remain protected against the acidic environment in the digestive system of the bumblebees. The method could also work with honey bees, because their digestive system has the same acidity. The authors suggest that the production of the microparticles could be an inexpensive way to protect pollinators from organophosphates.

However, it is not a panacea, British bumblebee expert Dave Goulson of the University of Sussex warns in an email. “I am concerned that this could be used as an excuse to continue to use malathion freely, which is a highly toxic substance to all animals, including humans. Even if the particles worked, animals that didn’t ingest them would still be poisoned. I also wonder how easy it would be to do something like that in the wild.”

The researchers themselves write that the enzymes could possibly be administered via special food containers in areas with intensive agriculture.