Researchers ID sex pheromone of invasive giant hornet

Date:
March 14, 2022
Source:
University of California - San Diego
Summary:
Scientists have developed a method for tracking the Asian
giant 'murder' hornet's presence and possibly accelerating its
removal. The researchers identified the major components of the
Asian giant hornet queen's sex pheromone, an achievement that
could be used as bait to trap and track the insects.



FULL STORY ==========================================================================
The world's largest hornet has been the focus of extensive news coverage
of late due to its menacing appearance and expanding footprint in North America.


==========================================================================
But while the "murder hornet" label attached to the Asian giant
hornet (Vespa mandarinia) may be an overdramatization of its danger, researchers agree that the invasive species is destructive and
threatens North American bee populations and millions of dollars in
crop production. Because honey bees offer few defenses, giant hornets
can rapidly destroy entire bee colonies.

"My usual plea is that people should stop calling them 'murder hornets'
because they are large and perhaps frightening but not truly murderous,"
said James Nieh, a Division of Biological Sciences professor and bee
researcher at the University of California San Diego. "They are amazing
social insects, but they don't belong in North America and harm our
critical bee populations, so we should remove them." But how to eliminate
them is not clear. Even knowing where they occur -- thus far reported
in Canada and the Pacific Northwest -- has been difficult to determine.

As one possible solution, Nieh his colleagues in China have developed a
method for identifying the Asian giant hornet's presence and possibly accelerating its removal. In the journal Current Biology, the researchers reveal the identification of three major components of the Asian
giant hornet queen's sex pheromone, an achievement that could be used
as bait to trap and track the insects. Using gas chromatography and
mass spectrometry, along with experiments spanning two years, Nieh and
his colleagues identified the major chemicals in the sex pheromone as
hexanoic acid, octanoic acid and decanoic acid, compounds that can be
readily purchased and deployed immediately in the field.

In a previous study, Nieh and his colleagues used a comparable approach
to identify the female sex pheromone of a related Asian hornet species
(Vespa velutina). In their new study, the researchers placed traps near
hornet nests, locations where they typically mate, and captured only
male hornets, but no females or other species. During their experiments
the scientists tested the hornet's neural activity and found that male
antennae are highly sensitive to the pheromone.



==========================================================================
"The males are drawn to the odors of the females since they typically
mate with them near their nests," said Nieh. "In two field seasons we
were able to rapidly collect thousands of males that were attracted to
these odors." Scientists are not clear how Asian giant hornets first
came to North America.

In recent years they have been documented in British Columbia and
Washington state, while modeling simulations indicate they could rapidly
spread throughout Washington, Oregon and possibly the eastern U.S.

Although the experimental pheromone hornet traps were set close to bee colonies, Nieh hopes they can be deployed in multiple field locations to evaluate whether they can chemically attract the hornets over distances
of a kilometer or more.

"Because these pheromone-based traps are fairly inexpensive I think they
could be readily deployed for sampling across a large geographic range,"
said Nieh.

"We know where they have been found, so the big question is whether they
are expanding. Where is that invasion front?" Instead of patenting the identification of the sex pheromone, Nieh and his colleagues decided to
publish their findings as quickly as possible in hopes of providing a
possible solution to help document the hornet's spread. As more pheromone
bait traps are deployed, a map could emerge along with predictive models
to assess where and how rapidly they are spreading.

"We hope that others, especially in invaded areas, will take the protocol
we have established and test this method," said Nieh. "We've described the chemical blends needed for these traps, which could reduce the number of
males available to mate with females to help depress the population but primarily would help us figure out where they are." Nieh's coauthors on
the Current Biology study include Shihao Dong and Ken Tan of the Chinese Academy of Sciences and Aili Sun of Yunnan Agricultural University.

Video of honeybees forming heat ball defense: https://youtu.be/vdald3H5c90

========================================================================== Story Source: Materials provided by
University_of_California_-_San_Diego. Original written by Mario
Aguilera. Note: Content may be edited for style and length.


========================================================================== Journal Reference:
1. Shihao Dong, Aili Sun, Ken Tan, James C. Nieh. Identification
of giant
hornet Vespa mandarinia queen sex pheromone components. Current
Biology, 2022; 32 (5): R211 DOI: 10.1016/j.cub.2022.01.065 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2022/03/220314120708.htm

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