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Honey bee-harming Varroa mites also a threat to other insects

New research has shown that the Varroa mite, which is a major causes of honey bee mortality, could also pose an indirect threat to many other insect species.

The study was carried out by researchers at Victoria University of Wellington, the Malaghan Institute of Medical Research and the University of California Riverside.

“The Varroa mite has spread throughout most of the world and is one of the biggest threats to honey bees,” says Professor Phil Lester from Victoria University of Wellington’s School of Biological Sciences. “Our research shows that the introduction of this mite could also have serious consequences for spiders, as well as butterflies, beetles, ants, and many other insects.”

The reddish-brown Varroa mite is a specialist parasite of honey bees and is about the size of a pinhead. It was found in New Zealand in 2000 and accidentally introduced into Hawaii in 2007-08.

The Varroa mite carries a range of other viruses and pathogens with it as it moves into new ecosystems, Professor Lester says.

The research completed by Professor Lester and his colleagues, and published today in Proceedings of the Royal Society B, shows that these viruses and pathogens affect a wide range of hosts.

“In particular, our study showed that the yellowjacket wasp, a honey bee predator, had been infected by strains of viruses carried by the Varroa mite, likely as a result of attacking and eating infected honey bees,” says Professor Lester. “It is likely these strains have spread to many other species’ too.”

The introduction of the Varroa mite in Hawaii has also led to the emergence of new, virulent strains of the Deformed Wing Virus (DWV). Current strains of this virus are responsible for the death of many honey bee populations worldwide.

“The arrival of the Varroa mite in honey bee populations in Hawaii has favoured a few virulent strains of DWV,” says Erin Wilson Rankin, an assistant professor of entomology at the University of California Riverside and lead investigator of the study. “The effects of the Varroa mite have cascaded through entire communities in Hawaii and probably around the world.”

The study focused on populations of honey bees and yellowjacket wasps, a common predator of honey bees, that live in Hawaii. The research analysed these insects before and after the introduction of the Varroa mite to Hawaii in 2007.

“Varroa is a serious issue for honey bees that needs to be managed,” says Professor Lester. “Our research shows that managing the Varroa mite will help many other insects as well.”

This research was supported by a Royal Society Te Apārangi Marsden grant, the United States National Science Foundation, the Hellman Fellows Fund, and the National Institute of Food and Agriculture of the United States Department of Agriculture.