Global invasion risk of Apocephalus borealis, a honey bee parasitoid

Published: 19 January 2021| Version 1 | DOI: 10.17632/8xwbvjbvmk.1
Erik Tihelka, John Hafernik, Brian Brown, Christopher Quock, Sofia Croppi, Chen-Yang Cai, Chao-Dong Zhu


Apocephalus borealis is a cryptic parasitoid of hymenopterans native to North and Central America that parasitizes honey bees (Apis mellifera) and is associated with infested bees absconding the hive to die outside. The flies can also harbour viral infections and nosematosis. Recently, nucleotide sequences identical to A. borealis were reported from bulk screenings of honey bees from Belgium and South Korea, although no adult flies have been collected. To predict the potential invasion risk of A. borealis across the world, we constructed a MaxEnt species distribution model based on occurrence data from North America submitted to the citizen science project ZomBee Watch ( We show that extensive parts of Europe, the Mediterranean Basin, Asia Minor, southern Africa, eastern Asia, Australasia, and North and South America show high degrees of climatic suitability for invasion, suggesting that the fly could establish in these regions. We discuss the status of A. borealis as an invasive species and measures that can be taken to reduce the risk of its introduction outside of North America. Our results highlight A. borealis as a potential threat to honey bee health worldwide that requires urgent attention of international veterinary bodies to prevent its spread.



University of Bristol


Diptera, Phorid, Honey Bee, Environmental Niche Modeling