A New Way to Save the Bees: Have Them Deliver Natural Pesticides to Crops

One of the most persistent and destructive problems in modern agriculture is its heavy reliance on pesticides. The United States alone uses about 1.1 billion pounds of these chemicals every year to protect flowering crops. The indiscriminate spraying doesn’t just pollute soil and water; it also kills many of the beneficial organisms those same crops depend on. That’s in addition to contamination of fruits and vegetables: Residues of 165 pesticides turned up in a 2013 U.S. Department of Agriculture sampling of the foods we eat every day.

But what if, instead of crop dusters blanketing fields with chemicals, you could use bees to deliver a precise dose of a treatment directly to the plants that need it? That is, what if you could piggyback on the vital work pollinating insects are already performing instead of inadvertently killing them?

That’s the idea in the technology called “entomovectoring.” Researchers in Canada and Europe have been experimenting for years with the idea of using bees (the “entomological” part of that word) as delivery systems (or vectors). They equip commercial beehives with trays containing a powder, and when bees are leaving the hive, they tramp through the powder and carry it on their limbs the way they carry pollen. When dosed with the appropriate bacterial, viral, or fungal additives, that powder deposited on the flower can protect a plant from a particular pest or disease. A Canadian company, Bee Vectoring Technology, has opened a factory to produce packets of its patented powdery “vectorite” customized for particular crops. ‎The biological agent BVT uses is a naturally occurring fungus that the company says does not harm the bees.

In entomovectoring studies, honeybees have worked best for large field delivery because they forage up to two miles from the hive. Bumblebees tend to stay close to home, sticking to within 400 to 600 feet of their nest. But they’re less aggressive than honeybees and more tolerant of temperature fluctuations, making them effective in greenhouses. European researchers have also experimented with mason bees, which can sometimes be better vectors because they visit each flower more often.

Despite initial concerns, the bees haven’t suffered major ill effects while delivering certain pest-killing viruses and bacteria to flowers. Certain sublethal effects, such as an increased rate of water loss, may pose a risk, though at far lower levels than with synthetic pesticides.

In an interview, Michael Collinson, chief executive at Bee Vectoring Technology, said entomovectoring can drastically cut the amount of a control agent and water needed to treat crops. With conventional spraying, a farmer typically applies several rounds of a pesticide during the bloom period, requiring as much as 600 gallons of water per acre. Even at that rate, as many as half the flowers may open and die, untreated, between spray intervals.

The bees, on the other hand, require no water, visit throughout the blooming season, and need to apply only a fraction as much of a particular protective substance. Moreover, the substances they deliver appear to benefit the entire plant, not just the flowers. In one study, honeybees delivered a treatment against fungi, insects, and mildew, and it later turned up in 96 percent of tomato leaves and 76 percent of sweet pepper leaves.

The need to apply large amounts of pesticides and fungicides using conventional spraying also has one other inevitable side effect: Resistance to a chemical tends to develop quickly, often in as little as three or four years. That doesn’t appear to be a problem with entomovectoring.

Because entomovectoring typically deploys biological control agents rather than chemicals, it can also qualify as organic. David Passifume, an organic farmer in Ontario, Canada, said his use of entomovectoring completely protected his strawberry crop from mold and rot even during the very wet 2015 growing season. After going organic, “we avoided some strawberry varieties because of their susceptibility to tarnish plant bugs,” Passifume said. But with entomovectoring, “we have gone back to planting them.”

For better or worse, entomovectoring has attracted interest from the opposite side of the agricultural world. An executive from agrochemical giant Syngenta (which is being acquired by ChemChina) now serves as an adviser to Bee Vectoring Technology. Rival Monsanto, which made a failed takeover bid for Syngenta last year, has also expressed interest in testing products with the company.

Thus the technology being touted for its ability to work with Mother Nature may yet end up as just another tool of the agro-industrial complex.