The Varroa destructor is a parastic mite that is a deadly enemy of western honeybees. The varroa mites transmit pathogens, including viruses and bacteria that may cause malformations and lethal infections for the bees, and has been held responsible for the high winter losses of Western honey bees in recent years.

To generate more data on the the dangerous Varroa destructor mite, Bayer partnered with the Frankfurt University Bee Research Institute to conduct a five-year field study with 2,500 beehives. The results indicate that the varroa mite can quickly re-infest bee colonies that were successfully treated, meaning that careful colony management is needed.

"We learned that we can reduce colony losses and protect bee health by reducing the reinfestation of varroa in late summer," explains Klemens Krieger, expert for bee health at Bayer HealthCare Animal Health. "But because the varroa mite is still an evolving target, we need to continually adapt treatment schemes and develop more treatment options against this deadly parasite."

These new findings, presented at the world largest gathering of beekeepers and bee-scientists, show the need for an integrated pest management approach to prevent bee colony losses caused by the varroa mite. The study results demonstrate that sustained treatment with Bayer’s acaricide containing polymer matrix carriers, especially in the critical period in late summer after honey extraction, controls mite infestations successfully and keeps winter colony losses low. They further show that an annual rotation of products with different modes of action can prevent adaptation of the mites to the active ingredients and keep efficacy of the applied products unchanged during the five year study period.

"For over 25 years, Bayer has been supporting bee keepers by researching solutions to protect honeybees," said Dr. Douglas Hutchens, Chief Veterinary Officer and Head of Global Development at Bayer Animal Health. "This recent study with Frankfurt University is an important step to increase our understanding of the epidemiology of the varroa mite over multiple seasons, the devastation that it causes, and help us identify new treatment regimens to best fight this parasite."