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Field Note

Juliet Carroll: Using hummingbirds to protect New York’s berries

A ruby-throated hummingbird spreads its wings.
A ruby-throated hummingbird spreads its wings. Photo by Shutterstock.
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By Juliet Carroll
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  • Cornell AgriTech
  • Cornell Cooperative Extension
  • School of Integrative Plant Science
I’m a senior extension associate for New York State Integrated Pest Management (NYS IPM), located at Cornell AgriTech in Geneva, New York. My program focuses on translating research into pest management solutions that reduce the pesticide footprint on fruit farms across the state.

Research at Cornell in fruit IPM has created solutions that, in some cases, have erased the need for pesticide applications. I work with CALS faculty and CCE educators to deliver IPM solutions to the fruit industry. I truly stand on the shoulders of giants — faculty, technicians, graduate students and postdocs who are doing translational research that benefits our fruit growers, their land, our food and our shared environment.

I love being outdoors — in the orchards when they’re in bloom, in the berry plantings when the pollinators are buzzing, watching the fruit develop and working to keep the plants healthy. I also love what IPM stands for – protecting the environment, minimizing the use of pesticides, protecting our crops and keeping farms in business.

However, IPM can get disrupted by invasive species. Spotted-wing drosophila (SWD) is one such species — a tiny vinegar fly, like the little fruit flies you’ll see in your kitchen in late summer. But this ninja pest has a serrated ovipositor so that it can slice into perfect fruit and then lay eggs inside. Their little hatchlings devour the fruit from the inside out, making delicious raspberries, blackberries, cherries and blueberries melt away, leaving a shriveled shell and numerous SWD pupae which, in turn, hatch into adult flies to start the cycle all over again.

Berries in a Cornell AgriTech high tunnel.
Juliet Carroll, senior extension associate.

The New York berry industry is valued at $20 million annually. CALS researchers such as Juliet Carroll help protect the livelihood of berry producers.

Juliet Carroll, senior extension associate for NYS IPM. Photo by Vivian Carroll Becker.

Before SWD hit New York state in 2012, most berry growers hardly ever sprayed, and some didn’t even own a sprayer. Now, these growers face a weekly insecticide spray regimen, and that’s where my work comes in. As part of the Cornell Berry Team, we worked tirelessly with the NYS Berry Growers Association to deliver workshops and educational materials about this invasive species.

During one workshop in 2014, a grower asked about using hummingbirds against SWD. What a novel idea, I thought; I hadn’t heard about it. But a Mississippi blackberry grower was doing just that — placing 100 hummingbird feeders in their 4-acre blackberry planting and keeping SWD at bay. Greg Loeb, professor of entomology, and Courtney Weber, professor of horticulture, suggested I test this out at Cornell AgriTech.

It’s a biological control measure that most people don’t think about. Yes, birds eat insects, and they can eat a lot of them. A female ruby-throated hummingbird feeding her young can consume about 2,000 tiny, soft-bodied insects per day — that’s a lot of SWD, or aphids, or gnats or tiny spiders!

The research was challenging. A flying pest and a flying predator? Try designing field experiments to measure that. We persevered, and over four years got three years of reasonably good data. Not great statistical separation, but the trends were in the right direction.

Bio-control using predators that eat pest species typically won’t provide 90-100% control of the pest, but natural enemies do knock the pest population down and alter the behavior of the pest. The best results we obtained were when both hummingbird and SWD numbers were high. We found trap catch was reduced by up to 59%, and fruit infestation was reduced by up to 56% in the area of the field with the hummingbird feeders compared to the area without feeders.

It is great to work with such a successful and collaborative team at Cornell. Our success with hummingbirds, hopefully, will be integrated into the larger picture of tactics that growers can use to manage SWD infestation in their fruit crops.

Each year something new comes out that we can translate into better, more bountiful, food production. We put together annual guides about the insecticides that are effective and legal to use in New York state, so growers have ready access to this important information. It’s super exciting to be on the front lines, helping growers combat pests with the best possible solutions – using IPM!

Read more about the Cornell Berry Team’s collaborative work to combat SWD.

Stay up to date by following NYSIPM’s Spotted Wing Drosophila blog, and contact Juliet directly for questions about using to hummingbirds to control SWD. Learn more in the Spring 2020 issue of Fruit Quarterly.

Additional resources for growers:

  • Network for Environment and Weather Applications — Pest forecast models for apples, blueberries, grapes and strawberries that use weather data to predict disease and insect risk.
  • Trac Software — An Excel-based program that automatically creates reports for processors and buyers about what they sprayed on their crops.