Project Overview

Reports

Commodities

• Animals: bees

• Fruits: apples, citrus, peaches, pears

• Pollinators: honey bees, other

Target Pests

Practices

• Pest Management: pesticide application timing

• Crop Production: application rate management, beekeeping/honey, pollination/pollinator health/habitat

• Production Systems: agroecosystems

Broadcast spray application of antibiotics in US fruit orchards have increased dramatically in the last decade in response to emerging and expanding bacterial agricultural pathogens. Yet we have almost no understanding of how these mass field antibiotic applications will affect beneficial organisms, including pollinators. Like humans, bees have beneficial bacteria that live in their gut and play a key role in digestion, nutrient absorption, and immune function. This is of concern because broad-scale antibiotic applications could disrupt these beneficial bacteria, with poorly understood but potentially negative impacts on bee health. There is a limited body of laboratory studies that suggest increased disease susceptibility and increased mortality of bees following antibiotic exposure, but much remains unknown. Additionally, pilot data from laboratory experiments of ours show that antibiotics can disrupt bee foraging behavior, raising the possibility that disruption of the bee gut microbiome could have adverse effects on crop pollination.

Here we propose to study how exposure to broadcast-spray antibiotics used in fruit orchards impacts bee growth, foraging, and pollination. We will carry out this studies in apple orchards because 1) antibiotic applications to apple orchards—including streptomycin and oxytetracycline—have dramatically increased due to rapid global expansion of the bacterial pathogen fire-blight; 2) managed and wild pollinators are essential to apple pollination and fruit production; and 3) antibiotics are sprayed specifically during the apple blooming period when bees visit the flowers, thus maximizing the chance of bee exposure to antibiotics. We will work in apple orchards in north Georgia with and without antibiotic application. We will place honey bees, bumble bees, and blue orchard bees in orchards to assess antibiotic residues in their brood, pollen, and honey, and changes in bee pollinating behavior before, during and after antibiotic applications. In addition, we will examine apple pollination outcomes in control vs. antibiotic-exposed fields.

Our work will contribute to the fundamental understanding of how antibiotics could impact bee health and pollination services. We expect to disseminate our findings in the scientific literature and through extension programs targeted to Southern fruit tree growers.