1,400 different bug species found in the guts of Asian hornets

One of the world’s largest hornet species appears to have quite a diverse palate. When studying the Asian hornets’ (Vespa velutina) gut contents, a team of researchers from the University of Exeter in the United Kingdom, they found evidence of 1,400 different species–including some crucial pollinators. The team saw a wide range of insects such as bees, wasps, beetles, flies, butterflies, moths, and even some arachnids. The findings are detailed in a study published March 4 in the journal Science of The Total Environment.

What are Asian hornets?

Also known as yellow-legged-hornets, Asian hornets are a social species of predatory wasp. They are about one inch long and can build nests that can contain up to 6,000 workers. They are native to southeastern Asia and considered an invasive species in Europe and North America. They are particularly threatening to honey bees and other native insects that pollinate important crops. The lack of pollinators can threaten food supplies and the ecosystem as a whole. 

Asian hornets are not to be confused with the headline grabbing “murder hornets” (Vespa mandarinia). They are a different species and were successfully eradicated in the United States last year after first being spotted in 2019. 

You are what your parents eat

In the new study, the team looked at Asian hornet samples from France, Spain, and the island of Jersey throughout the hornet’s active season. The European honey bee was the most common species found in the hornets’ guts, and appeared in all of the sample nests and the larvae from those nests. However, their diet appears to be much more broad than initially expected. 

“Asian hornets are known to prey on honey bees, but until now the full range of their diet hasn’t been tested,” study co-author and University of Exeter molecular ecologist Siffreya Pedersen said in a statement. “The diet varied strongly over the seasons and between regions, showing that they are highly flexible predators. “Most insect populations are in decline due to factors such as habitat destruction and chemical pollution. The expanding area inhabited by Asian hornets poses an extra threat.”

The team used a method called deep sequencing–which sequences a region of the genome multiple times–to identify the prey species in the guts of more than 1,500 Asian hornet larvae. The larvae typically eat food that is provided by adult hornets. 

Of the top 50 invertebrate prey species that the team identified, 43 are known to visit flowers. Europe’s top three main crop pollinators–the European honey bee, the buff-tailed bumblebee and the red-tailed bumblebee–were also represented in the samples. 

[ Related: How a single honey bee colony led to a species invasion. ]

“Insects play vital roles in enabling ecosystems to function–including pollination, decomposition and pest control,” Pedersen said.

According to the team, this provides additional evidence of the threat that Asian hornets pose as they spread. Gardeners and the general public are encouraged to get to know what these hornets look like and report their nests to local authorities. 

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