When he referred to a ‘30 percent reduction in hive numbers if the hornet was to become established’, how did he land on this number when some areas in Europe the loss of beehive colonies as a result of the Yellow-Legged Hornet is up to 80%?

Answer

I am advised that the impact of Vespa velutina on national colony losses is not well quantified. The 30 percent figure is derived from modelling conducted in France, which estimated that up to 29.2 percent of nationwide colonies could be lost under certain conditions. This is a modelled worst-case scenario, not an observed loss rate, and is often misrepresented in secondary sources as though it were actual field data.