Honeybees are essential to the health of the world’s food supply, and they are dying off in dramatic numbers, at alarming rates. Unless more is done to help these bees, the domino effect of the loss will be felt by humans. New work from scientists at the Lawson Health Research Institute (Lawson) and Western University could provide some much-needed assistance; it seems that probiotics could shield honeybees from the harmful effects of pesticides.
The importance of honeybees to agriculture cannot be overstated; they pollinate roughly 35 percent of the world’s food crop. While pesticides have been helpful to farmers wanting to boost crop yields, there have been trade-offs. The most common pesticides, neonicotinoid insecticides, have bee implicated as major contributor to colony collapse disorder - found to be responsible for the deaths of entire populations of honeybees.
"The demise of honey bees would be disastrous for humankind. A current dilemma in agriculture is how to prevent bee decline while mitigating crop losses," explained Dr. Gregor Reid, Director for the Canadian Centre for Human Microbiome and Probiotic Research at Lawson, and Professor at Western's Schulich School of Medicine & Dentistry. "We wanted to see whether probiotics could counter the toxic effects of pesticides and improve honey bee survival."
In this study, published in Scientific Reports, a common model of pesticide toxicity was used, fruit flies, which have a high degree of similarity to honeybees. They react in a similar way to neonicotinoids, the immune systems are like one another, and there are lots of microbiota species that are common to both insects.
First it was confirmed that they pesticides have an impact on the microbiota. Indeed, after exposure to a realistic amount of imidacloprid (IMI), one of the most common pesticides on the planet, flies became more susceptible to infection and had alterations in their microbiota.
The researchers then gave the fruit flies a specific kind of lactobacilli, a probiotic bacterium. Survival among the fruit flies significantly improved. The immune system was being stimulated by a chemical pathway activated in insects by stresses like heat and infection.
"Our study showed that probiotic lactobacilli can improve immunity and potentially help honey bees to live longer after exposure to pesticides," said Daisley, an MSc candidate. He noted that pollen patties can be used to expose the bees to lactobacilli, as they are already used by beekeepers to ensure bees get the right nutrition.
In Canada, bee keepers are reporting rising rates of bee death. During winter, mortality rose steadily, ranging from 38 to 58 percent in the past few years, a rate two to three times higher than what is considered sustainable. Following an abnormal number of bee deaths in Ontario, it was found that over 70 percent of the dead bees carried neonicotinoid residues.
"While cessation of pesticide use would be ideal, farmers currently have little alternative to obtain the yields that keep their businesses viable," said Dr. Reid. "Until we can cease using pesticides, we need to find ways to protect humans and wildlife against their side effects. Probiotics may prove as an effective protective intervention against colony collapse disorder."
Learn more about the challenges colony collapse disorder may present to us in the future.
Sources: AAAS/Eurekalert! via Lawson, Scientific Reports