Ten years ago, Juliet Carroll was intrigued when a New York state berry grower asked if hummingbirds could be used to prey on spotted-wing drosophila (SWD), a pest species new to the region but quickly wreaking havoc on the state’s $20 million berry industry.
Now, a Cornell study by Carroll, who is a senior extension associate for New York State Integrated Pest Management at Cornell AgriTech, entomology professor Greg Loeb and others recently published in ScienceDirect shows hummingbirds reduced SWD fruit infestation levels by up to 64% in field trials.
The pest, which is native to Southeast Asia, was first discovered in New York state by Cornell in fall 2011. By the next year, blueberry fields were swarmed by the insects. Growers lost up to 80% of their blueberry crop, and nearly all raspberry and blackberry crops were destroyed.
The invasive insect attacks fruit just as it’s beginning to ripen. Females, which can lay 2,000 eggs per day, deposit their eggs in soft-skinned fruits, especially berries and cherries. Within a few days, fruit begins to wrinkle and crater as larvae feed and grow.
In an effort to address the problem, Cornell researchers and growers have experimented with a variety of control measures, including insecticides, pruning to create more open canopy for better spraying and netting. Hummingbirds, which can eat up to 2,000 insects per day, were added to the Cornell research mix in 2015.
Carroll, Loeb and Courtney Weber, professor of horticulture, first put feeders in raspberry field plots at Cornell AgriTech, then worked with commercial raspberry farms in the region. In addition to showing reduced SWD fruit infestation levels, their research over the next five years indicated that ruby-throated hummingbirds spent time in raspberry plantings that had feeders and that 81% of hummingbird flights to feeders showed potential for predation of SWD. They also found that hummingbirds were particularly present when raspberry fruits were susceptible to SWD infestation.
David Stern, owner of Rose Valley Farm in Wayne County, grows 40-50 types of crops on 80 acres, including organic blueberries, and admits to being skeptical when Carroll approached him about putting hummingbird feeders in his fields as part of the research trial.
Today he is a believer.
“Hummingbirds are part of a very big picture, along with pruning and organic sprays we use,” Stern said.
“While we can’t expect hummingbirds to eliminate the problem, they certainly help,” said Loeb, who added that for growers with u-pick operations who are big on agrotourism, “Having the hummingbirds adds to that experience.”
Carroll believes her research is part of an effective, integrated approach for growers to manage SWD.
“Hummingbirds are so pugnacious. They are really fun to be around,” she said. “Things are looking bright for the berry industry.”
Mike Hibbard is a freelance writer for Cornell AgriTech.
We openly share valuable knowledge.
Sign up for more insights, discoveries and solutions.