For the first time, bee researchers have identified “synergistic interactions over time” between Varroa parasite mites and neonicotinoid insecticides. Two stress factors indicate that recent research reduces the survival of bees in the winter.
Some studies clearly show the negative effects of neonicotinoids on bee health, and varroa mites are now ubiquitous in bee colonies. However, studies that examined the effects of two stressors in combination have led to inconclusive results.
For the new study, scientists released bee colonies free from two neonicotinoid insecticides, thiamethoxam and clothianidin, by eating pollen paste. The mass and longevity of bees that work is not affected.
However, when scientists discovered colonies infected with ectoparasitic destructor Varroa, they measured a negative synergistic effect on bee health. However, negative effects were measured only 16 weeks after exposure to neonicotinoids.
In temperate regions, bees must survive in winter to have colonies. The synergistic effects of unsuitable tick times and neonicotinoid exposure can explain the prevalence of colonies collapsing in winter.
Scientists have published the results of their study in Scientific Reports this week.
“Future mitigation efforts should focus on developing sustainable agro-ecosystem management systems that include reducing the use of neonicotinoids and sustainable solutions for V. destructive mites,” the researchers wrote.