Microparticles that detoxify insecticides in bee guts could help beekeepers keep their hives healthy and productive, according to a new study.
Researchers, whose findings were published Thursday in Nature Food, developed pollen-mimicking particles containing an enzyme that breaks down organophosphates, a process that could help bees survive lethal doses of these commonly used agricultural chemicals.
"Bees aren't doing too well in general, but one of the main reasons why that's the case is because of pesticide exposure and pesticide application and, more specifically, the proliferation of industrial agriculture and the monocultures which go along with that and the heavier amount of pesticides, which bees are coming into contact nowadays," said James Webb, study co-author and founder of the company Beemmunity. He did this work as a master's student in biological and environmental engineering at Cornell University.
Although the volume of pesticides applied in the U.S. has decreased in the last 25 years, modern agrochemicals are much more toxic to pollinators, and even small doses of these chemicals can harm bees and other beneficial insects as they perform essential crop pollination services.
Organophosphates are among the pesticides that bees encounter in agricultural landscapes. These neurotoxic insecticides may kill bees or can have more subtle impacts on movement, immunity and learning.
To help bees cope with exposure to organophosphates, Webb and his colleagues designed microparticles that encase an enzyme that breaks down and detoxifies these chemicals.
The microparticles are made of calcium carbonate, a nontoxic substance that protects the enzyme from the acidic conditions of the bee foregut. About the size of pollen grains, the particles pass through the bees' gut filter that separates liquids and coarse particles. Liquid nectar remains in the foregut and is later regurgitated into honey, while pollen — and microparticles — are filtered into the midgut for digestion.
The team measured how well the microparticles detoxified organophosphates in small lab colonies of bumble bees. When bees chowed down on pollen laden with organophosphates, either malathion or paraoxon, they all died. But the addition of detoxifying microparticles to bees' diets boosted survival rates to 38% in bees that received paraoxon and 80% to 100% in those that received malathion.
According to Webb, beekeepers could use these microparticles to protect managed hives of honeybees and bumble bees from exposure to insecticides. The particles could be easily incorporated into supplemental foods such as sugar syrups and pollen patties, and a single meal could provide insects with ongoing protection.
"A bee typically won't go to the bathroom for a long time," Webb told The Academic Times. "It will sometimes go up to three weeks without going to the bathroom. So our microparticles are hanging around in the bee gut during this time and doing their work."
Bumble bees were used for this study, but the researchers are now doing a field trial with hundreds of honeybee hives to see how well the microparticles perform on a larger scale when insects are exposed to other stressors in the environment, such as Varroa mite, a notorious parasite of bees.
"A lot of literature nowadays finds that pesticide exposure exacerbates all these other stresses that bees go through, so we're looking to show that we can improve those factors as well," Webb explained.
Organophosphates are just one component of the pesticide "cocktail" that pollinators are exposed to in the environment, Webb said. For example, a recent study found 91 different insecticides, herbicides and other agricultural chemicals in honeybee hives.
The use of probiotic bacteria is another approach that some researchers are exploring to mitigate the harmful effects of pesticides on bees.
The researchers behind the new study have also developed a different type of microparticle that targets a broad spectrum of pesticides, which will be described in a forthcoming study.
"We use insect proteins to actually sequester the pesticides rather than break them down, and so we use what's more of a micro-sponge," Webb said. "The microparticles specifically capture pesticides in the bee gut, and the bee kind of poops them out."
Webb and Beemmunity have incorporated the micro-sponge technology into sugary bricks referred to as bee "candy bars." These bars and other products are designed to help not only managed bee colonies but also wild bees, which are important pollinators for wild plants and crops.
The study, "Pollen-inspired enzymatic microparticles to reduce organophosphate toxicity in managed pollinators," published May 20 in Nature Food, was authored by Jing Chen, Kaavian Shariati, Scott McArt and Minglin Ma, Cornell University; James Webb, Beemmunity; and Shengbo Guo and Jin-Kim Montclare, New York University.