Antibiotic spray affects bumblebee cognition

Researchers determine that a common treatment for fire blight in fruit orchards can hurt the pollinator’s foraging ability

In recent years, the use of streptomycin antibiotic spray has increased as orchard farmers fight a rise in plant bacterial infections caused by pathogens such as Erwinia amylovora.

Fire blight can turn blossoms and shoots of apple and pear trees black, making them look like they were scorched by fire. Citrus greening, also known as yellow dragon disease, turns citrus fruits green, bitter, and unusable. As a result, millions of acres of crops have been devastated by these diseases across North America and around the world.

To complicate matters, streptomycin resistance has been detected in the pathogen across regions of Canada and the United States.

But just as pests adapt to the antibiotic spray, beneficial pollinators such as bumblebees are adversely affected. Researchers at Emory University in Atlanta, Georgia, have found that exposure to upper limit dietary streptomycin decreases a bee’s foraging choice accuracy and increases its avoidance behaviour.

There is increasing evidence that suggests insect gut microbiomes play a role in learning and behaviour, which are essential for the survival of pollinators and their pollination efficiency, but which could be disrupted by antibiotic exposure.

Berry Brosi, associate professor in the department of biology at the University of Washington, said there has been work in other insects, like fruit flies, that suggests there is a “gut-brain axis” that aid insect learning, cognition, and behaviour.

“Interestingly, there is also evidence of some relationship in humans, mice, and other mammals, but perhaps not as strong as in insects, which have relatively simple nervous systems compared to mammals,” he said.