Scientists from the University of Exeter have investigated the effects of invasive Asian hornets (Vespa velutina nigrithorax) — which are considered a proliferating threat to pollinators in Europe and Asia — upon colonies of native European buff-tailed bumblebees (Bombus terrestris terrestris).
Vespa velutina nigrithorax — colloquially known as the yellow-legged or Asian hornet — was the first insect to be legislatively classified as an invasive alien species of concern in Europe.
This social species is native to Southeast Asia, but has spread rapidly through parts of east Asia and Europe, following accidental introductions in or before 2003 and 2004 respectively.
The invasion front has expanded at a rate of up to 78 km per year in some regions, facilitated by an adaptable life-history, rapid colony population growth, and the ability of mated queens to travel substantial distances in a single day.
Control efforts are further hampered by the difficulty of locating nests, and high potential for additional human-mediated dispersal events, as is the case with many other invasive insects.
While the impact of Asian hornets on managed honeybees is well-documented, effects upon other pollinator populations remain poorly understood.
“Asian hornets prey on a wide range of insects, including honey bees, but little is known about their impact on other pollinators,” said Dr. Thomas O’Shea-Wheller, a researcher in the Environment and Sustainability Institute at the University of Exeter.
“With honeybees, the hornets do something called ‘hawking’ — hovering outside the bees’ nest and attacking returning foragers as they fly past.”
“We recorded hornets doing the same thing to bumblebees, but with the surprising difference that in our observations, they were entirely unsuccessful.”
To assess the impact of Asian hornets on colonies of buff-tailed bumblebees in a representative environment, the authors established 12 field sites from an initial…
Read the full article here