Varroa Mite

Varroa destructor is a small (1.6 mm) parasitic mite that attaches to adult honey bees and bee larvae, feeding on the bee's fat body — a tissue critical to bee immunity and overwintering survival. The species jumped hosts from the Asian honey bee (Apis cerana, which co-evolved with varroa and tolerates her) to the Western honey bee (Apis mellifera, with no evolutionary defenses) sometime in the 1950s. Within decades, varroa spread globally — by 2010 the only varroa-free region remaining was Australia, where strict biosecurity has held the line. Varroa is the single greatest factor in modern honey bee colony losses worldwide. Beyond the direct fat-body feeding, varroa is the major vector of Deformed Wing Virus (DWV) and several other bee pathogens. Untreated varroa infestations destroy a colony within 1-3 years. The global beekeeping industry spends an estimated $2 billion per year on varroa control via miticides, breeding for varroa-resistant bee strains, and integrated pest management. New approaches in development include RNA interference treatments and gene-edited Varroa-Sensitive Hygiene (VSH) bee lines. The honey bee crisis is largely the varroa crisis.