Effects of field antibiotics on bee foraging behavior and pear pollination

On-Demand

Presenting Author(s)

LA

Laura Avila

Postdoctoral Fellow
Emory University
Doraville, Georgia

Co-Author(s)

CM

Christopher T. McCullough

Postdoctoral Researcher
Washington State University
Wenatchee, Washington
AS

Annie Schiffer

Utah State University
Logan, Utah
JM

JoMari Moreno

University of Washington
Wapato, Washington
NG

Neha Ganjur

Emory University
Atlanta, Georgia
Louis B. Nottingham

Research Assistant Professor
Washington State University
Wenatchee, Washington
Nicole Gerardo

Emory University
Atlanta, Georgia
BB

Berry Brosi

Emory University
Atlanta, Georgia

Antibiotics are a crucial tool for managing plant pathogens. During warm and wet springs, pear and apple growers use antibiotics to control the spread of fire blight, Erwinia amylovora. Spring is also a time of increased bee activity in orchards, as honey bees (Apis mellifera) are brought in for pollination. This is concerning because several laboratory studies have shown antibiotic exposure can impact honey bee and bumble bee foraging behavior. We tested the effects of antibiotic (oxytetracycline) vs. non-antibiotic (Aureobasidium pullulans) sprays for fire blight on bee foraging behavior. Ten commercial pear orchards in eastern Washington were sprayed with either treatment during bloom to control fire blight. In the field, we monitored the number of flowers visited and handling time per individual honey bee pre and post fire blight treatment, and pollination success via fruitset. In the lab, we tested the impact of recommended field-dose rates of both products on yellow-faced bumble bees (Bombus vosnesenskii). The field study revealed the number of flowers visited decreased after antibiotic application while the opposite was true after biological spray. However, pear pollination rates were unaffected by treatment type. In lab studies, bees exposed to the commercial full dose of oxytetracycline for 48 hrs were less likely to approach a sucrose reward compared to bees fed control (sucrose) and biological diets. Our work is a first step towards understanding whether field antibiotics disrupt bee foraging behavior and associated pollination services.