Alternatives to conventional farming can get pretty out-there: biodynamic farming, for example, utilizes cow horns filled with shit and buried underground, flower-filled stags' bladders hung in a tree, and cosmic forces swirled into a bucket. And now, in a Freudian twist on green agriculture, a growing number of fruit farmers around the world are managing pests by spraying their orchards with pheromones—the communicative sex chemicals that insects emit—confusing the bugs and reducing their impact on the farmers' crops.
For the past four years, Semios—a Vancouver-based technology company that develops high-tech, minutely calibrated agricultural products for tree fruit and nut growers—has been working on a pheromone-delivery system that helps both organic and conventional growers in the US, Canada, and Europe reduce their reliance on conventional pesticides.
In what the company calls a "precision farming platform," Semios' wireless sensors and controls monitor orchard conditions such as temperature and humidity, delivering farmers real-time updates on their smartphones. One of the pieces of equipment that the company manufactures is a pheromone-misting dispenser that releases exact chemical replicas of the pheromones put out by common fruit pests such as codling moths, whose larvae are the so-called "worms" that commonly end up inside apples.
Reached recently by phone, Michael Gilbert, Semios' CEO and a chemist by training, explained how Semios' technology works. One of the main ways in which insect pests cause damage to fruit, he explained, is when a male and a female mate, the female lays eggs on the fruit, and the eggs hatch into larvae that then feed upon that fruit. With Semios' pheromone mist, Gilbert said, "we prevent that whole process from happening."
A female moth, Gilbert explained, will find mates by emitting pheromones that communicate her sexual readiness as well as her location. When males sense those pheromones, they seek her out for mating. But on a farm equipped with pheromone dispensers, male moths will end up at one of those misters, not next to a female. They won't be able to mate, and over time, Gilbert said, the local pest population will drop as the insects' lovemaking habits are continually thwarted.
"Just a tiny amount of the pheromone chemical—which we reproduce exactly in the lab—is enough to confuse all the males in the field," he said.
For farmers, the major draw of using pheromones to manage pests is that the chemical signals won't affect the bugs that actually help out in orchards, such as ladybugs, which eat crop-attacking aphids. Because only codling moths will respond to codling moth pheromones, other creatures will go about their activities as normal.
"Any crop has a subset of insects that are damaging, and a subset of insects that are doing good," Gilbert explained. "That's the big challenge of classical pest management. The 'kill everything in sight' approach of chemical pesticides harms beneficial insects, too. But the beauty of pheromones is that they're species-specific."
Allen Godwin is the second-generation owner of Godwin Organics in Washington State, where he grows apples, pears, and cherries on his small-scale orchards. For him, the targeted nature of pheromones is the technology's most appealing feature.
"The easiest thing in the world is to go out and spray chemicals every day," he said. "But building up the natural predators of crop pests is a big part of our integrated pest management strategy, so that's just not possible. We don't like spraying, and it's expensive."
Although chemical pheromones are much pricier than chemical pesticides, Gilbert explained, they're more cost-effective for farmers over the long run. Whereas with pesticides farmers often have to spray continually, Semios technology is able to detect the conditions when pests will be most active—at a particular time of year, for instance, or when the weather is unusually warm and humid—and will emit the pheromones only on those nights, using just a small amount of product.
Godwin Organics is currently on its second season of using Semios pheromone misters, and Godwin said the system has worked well for him: he's noticed a drop in the local codling moth population, a decrease he said would be more dramatic if other growers in the area would adopt the technology, too
"It's very useful in what we're doing, and we're planning on continuing forward with the system," he said. 'Smart farm technology' overall, Gilbert added, will likely continue to spread among growers both large and small. "I see application for this project even farther than where's it been taken today," he said. "In five years, I think many more growers will have adopted these kinds of programs."