Hawaiian researchers say they've cracked one of the mysteries surrounding the biggest threat to the world's honey bee population.
A paper published in the journal Science helps to explain how the deadly bee parasite, the varroa mite, spreads a virus which kills millions of bees each year.
When the deadly varroa mite arrived in Hawaii five years ago, it wiped out the entire wild bee population and killed 60% of bees in hives, the ABC reports
The University of Hawaii's Ethel Villalobos is one of the researchers looking into the mite pest.
Her team found that, in colonies where varroa mite was present, a strain of a disease called deformed wing virus was stronger and deadlier.
She said the virus is hitching a ride in the mite that makes it spread faster, and it infects more bees.
Researchers found on the islands in Hawaii where the varroa mite was present, the deformed wing virus was in nearly all colonies. But in islands that are free of the mite, the virus was present in only 10% of colonies.
The mite was discovered in New Zealand in 2000 and has spread around the country since, causing a drop in crop yields, export revenue and honey production.
Australia is one of the only countries to remain free of the lethal pest.