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Why are hornets so successful as invasive species?

Hornets are the largest types of social wasps and play critical ecological roles as top predators. In their native regions, for instance, they act as natural pest controllers, helping to regulate populations of insects such as flies, caterpillars, beetles, and other types of wasps, thus contributing to healthy, functional ecosystems, while also benefiting agriculture. 

However, hornets often become established in areas they are not native to, where they tend to be very successful as invasive species. In such cases, they may cause major ecological and economic damage by preying on important pollinators, such as honeybees, wild bees, and hoverflies.

To better understand why hornets have been so successful as invasive species around the world, a team of researchers from University College London (UCL) has sequenced for the first time the genomes of the European hornet (Vespa crabro) and the Asian hornet (Vespa velutino), and compared them with that of the giant northern hornet (Vespa mandarinia), which was recently decoded by another research team.

While the European hornet is an important top predator protected in several regions of Europe, the invasive yellow-legged Asian hornet has become established through much of Europe over the past two decades, threatening native ecosystems, and the giant northern hornet – a species known for its critical role as a pest controller, pollinator, and food provider in its native Asian range – has only recently arrived to North America, where it could possibly threaten native fauna.

By analyzing the differences among the genomes of these three species, the experts identified genes which have been rapidly evolving since the species differentiated themselves from other wasp species and from one another that are particularly related to communication and olfaction.

“We were excited to find evidence of rapid genome evolution in these hornet genomes, compared to other social insects. Lots of genes have been duplicated or mutated; these included genes that are likely to be involved in communication and in sensing the environment,” explained study lead author Emeline Favreau, an entomologist and evolutionary biologist at UCL.

“Hornets are carried to different parts of the world accidentally by humans. All that is needed is a small number of mated queens to be transported, hidden in cargo perhaps. The genomes suggest that hornets have lots of genes involved in detecting and responding to chemical cues – these may make them especially good at adapting to hunt different types of prey in non-native regions,” added co-author Alessandro Cini, a zoologist at the University of Pisa

Sequencing these hornets’ genomes can provide important information about their ecology and evolution that other methods cannot, and may thus help improve the management of hornet populations both for their ecosystem services in their native ranges, and as ecological threats in regions where they are invasive.

The study is published in the journal Nature Scientific Reports.

By Andrei Ionescu, Staff Writer


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