Most people are familiar with fruit flies, which usually appear when ripe fruit is left out.
But growers in Abbotsford are dealing with a new species of the pest – new to B.C. – that has evolved a serrated “saw,” which allows it to cut through the skin of healthy, still-plump fruit, and lay eggs in it.
Ministry of Agriculture berry specialist Mark Sweeney explained the spotted wing drosophila is damaging to crops because the fruit goes soft.
“The products we harvest need to have shelf life,” said Sweeney, adding that blueberries in particular are typically shipped long distances.
He said blueberries are a popular crop locally, but the fly does not discriminate, and will go after grapes, all berries and all sweet, soft-skinned fruits.
“It can be quite damaging.”
The federal government has allowed farmers to spray insecticide to protect their crops, on an emergency basis, which causes concern in the organic farming community.
The spotted wing drosophila is common in China and other parts of Asia, but was first found in B.C. in 2009. In 2010, farmers faced their first full growing season with the bug present, and it was a challenging year. In 2011, populations were lighter. This year, the fly infestation was heavier early in the season, but at this point appears to have abated somewhat.
Government entomologists and producer associations are scrambling for a solution.
“There’s a whole lot of work going on in North American, and in fact around the world,” said Sweeney.
The federal government has approved five insecticide sprays for producers to protect their crops.
Emergency registration products approved for the control of spotted wing drosophila in B.C. for the 2012 season are Delegate (spinetoram), Entrust (spinosad), Malathion (malathion), Pyganic (pyrethrins) and Ripcord (cypermethrin). Both Entrust and Pyganic are acceptable for organic crop production.
These sprays have been tested for safety, said Sweeney.
He said spraying is “a fact of life with growing agricultural crops,” and added it is always advisable to wash fruit before consumption.
The provincial government has traps throughout the cropping region so it can track the spotted wing drosophila population.
“We don’t want to be putting on unnecessary sprays,” Sweeney said.
However, according to those who produce organic food, spraying insecticides to deal with the spotted drosophila is a knee-jerk reaction that highlights the problems in B.C. agriculture.
Chris Bodnar is a director with the B.C. Association for Regenerative Agriculture, which gives farms their “certified organic” status, and he also farms at the Glen Valley Organic Farm Cooperative.
Bodnar has made the decision not to use even the sprays that would allow him to keep his certified organic status, because of the effect they could have on the ecosystem.
“The problem is, it is also lethal to pollenaters, like bees,” he said.
What’s more, he said the too-frequent use of insecticides can have seriously unintended consequences, as bugs build up resistance.
“If you misuse it, you risk creating superbugs,” he asserts.
The Glen Valley farm grows a wide variety of crops including carrots, beets, parsnips and greens, and the produce is sold at farmers markets. Bodnar includes other plants such as flowers in the field, and these will attract predator insects such as ladybugs and wasps.
He said because so many producers plant the same berry crops in B.C., any threat to that crop is heightened. Canadian agriculture is too reliant on international export crops, he said, and must be more diversified.
“It has the potential to be a disaster, and that’s why people were quite concerned.”
And because so many producers plant only one crop, the risk of losing all their income for a season is a possibility.
“I understand very much the risk a lot of growers are under.”
However, he said the spotted wing drosophila can’t be killed off by spraying, because of all the blackberries, salmonberries and thimbleberries that grow wild in the region, and could sustain the flies even if all other fruit is sprayed.
“It’s not realistic to eliminate a pest – you have to manage it,” he said.
Sweeney said the flies have to be put in perspective. As damaging as the drosophila and these other hazards can be, an untimely week of downpour, early frost or other weather event can cost producers millions.
“They are another unfortunate challenge.”