The predation impact of ruby-throated hummingbird, Archilochus colubris, on spotted-wing drosophila, Drosophila suzukii, in raspberry, Rubus idaeus

Abstract

Hummingbirds require arthropods in their diet and may consume 2000 small insects per day, including drosophilids, when nesting. In New York, we investigated the use of feeders to attract Ruby-throated Hummingbirds, Archilochus colubris (Linnaeus, 1758), into red raspberry, Rubus idaeus L., to encourage predation of the spotted-wing drosophila, Drosophila suzukii Matsumura. We investigated whether fly populations and fruit infestation would be reduced in the half of the field with feeders compared to the half without. Over four years, 2015–2018, 81% of 266 hourly observations of hummingbird behavior found they were occupying the field when utilizing the feeders, supporting opportunities for predation on D. suzukii. In 2016 to 2018, when maximal hummingbird sightings were reached, significant reductions in D. suzukii trap counts and fruit infestation levels were obtained in some weeks in the half of the field provided with feeders at a density of 62 feeders/hectare. Compared to the half without feeders, the final tally of cumulative trap counts and fruit infestation levels were lower in the half of the field treated with feeders in all years. In comparing two paired commercial raspberry fields (in 2020), one with feeders at a density of 151 feeders/hectare and the other without feeders, presence of feeders significantly reduced trap counts in most weeks during the fruiting season. No Ruby-throated Hummingbirds were observed in the commercial field without feeders. Hummingbirds may protect fruit from D. suzukii when they are encouraged with feeders to visit and occupy raspberry plantings. The presence of hummingbirds in raspberry fields has the potential to contribute to a D. suzukii integrated management program and reduce the reliance on pesticides.