A new weapon in pest control: bug-mounted drones

What began as a side project while he was taking an integrated pest management class at Cal Poly, San Luis Obispo, has turned into a business for Chandler Bennett: spreading beneficial insects from drones.

Bennett founded Parabug, headquartered in Salinas, a year after graduating from Cal Poly in biological resources and agricultural engineering.

The company's website opens with these words: "The Future of Farming is Smaller Than You Think." A logo fancifully depicts an insect descending with a parachute.

The bugs don't have parachutes, of course. Instead, they are released through small holes on tubes attached to drones. The tubes slowly rotate to prevent clogging as releases of insects, eggs or larvae are calibrated for uniformity.

Bennett said the savings on release by drones range from 50% to 75% of the cost for release by hand. He said the cost is "on par" with insecticide sprays.

The cost for application from drones ranges from $16 to $25 per acre, and the cost of the predatory insects ranges from $50 to $100 per acre.

Bennett recently told the San Joaquin Wine Growers Association there are both benefits and challenges to the use of insect biocontrols.

Unlike pesticides, biocontrols have no re-entry restrictions and no postharvest intervals. The insects are highly mobile, and there is little or no development of resistance.

But there are challenges.

"You are working with a living organism," Bennett said. "They leave. They die.There are no guarantees."

Bennett said large orders can require long lead times for the insectary. There has been very little applied research and data available for outdoor crops, though there is more data on greenhouse use of biocontrols.

"We have qualitative but need quantitative data," he said.

Among weapons in his aerial arsenal is Cryptolaemus montrouzieri, also known as the mealybug destroyer. The insect can be used to target the vine mealybug, a significant grapevine pest.

Parabug has also applied predatory mites, lacewing eggs and larvae, the minute pirate bug and trichogramma, a parasitoid.

Among the company's customers is Michael David Winery of the Lodi area, where mealybug destroyers were released over a vineyard.

Almond growers, including Kern County farmer Kent Stenderup, have used drones to release predatory mites to control spider mites. Stenderup also uses them to apply beneficial insects to grapes.

Madera County grower Mike Tydal said he also has fly-overs with "good bugs to eat bad bugs" in his certified organic raisin crop.

Tydal said he believes the aerial applications are more uniform than previous hand applications. He said he has not sprayed "in quite a few years."

Bennett said scouting is a key to knowing when to release beneficial insects. It's also important to time pesticide applications accordingly and to use selective materials whenever possible. Growers should not spray right after or before a release, he said.

He suggested incorporating "insectary plants" that attract beneficial insects and provide alternative food sources.

Bennett said the western predatory mite is typically applied at 5,000 to 10,000 per acre but can range up to 20,000.

The mealybug destroyer is applied at 500 per acre. For the mealybug parasitic wasp, it's 250 to 500 per acre. For the green lacewing, it's 20,000 eggs per acre.

Bennett said it's important to ensure that those making applications are certified drone pilots and to check credentials. He said they must request a certificate for operation of a drone and furnish a pest control pilot's license and proof of insurance.

Drones can fly no higher than 400 feet above the ground and must not operate outside the visual line of sight.

If the farm is within 5 miles of an airport or similar controlled air space, let the application company know, Bennett said.

The applicator may need extra time to acquire a Federal Aviation Administration waiver and will also need tower approval prior to flight.

(Dennis Pollock is a reporter in Fresno. He may be contacted at agcompollock@yahoo.com.)