Asian giant hornet

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The Asian giant hornet (Vespa mandarinia), also known as the northern giant hornet,<ref name="ESA-NGH" /><ref>Template:Cite web</ref> and the Japanese giant hornet,<ref name="Vespa2020">Template:Cite journal</ref><ref name="Ross-9">Template:Cite book</ref> is the world's largest hornet. It is native to temperate and tropical East Asia, South Asia, mainland Southeast Asia, and parts of the Russian Far East. It was also found in the Pacific Northwest of North America in late 2019,<ref>BC Gov News: Asian Giant Hornet nest eradicated in Nanaimo.</ref><ref>USDA New Pest Response Guidelines: Vespa mandarinia Asian giant hornet.</ref> with a few more additional sightings in 2020,<ref name="WSDA1">Template:Cite web</ref><ref>Template:Cite web</ref> and nests found in 2021,<ref name="first-live-2021">Template:Cite web</ref><ref name="3rdnest">Template:Cite web</ref> prompting concern that it could become an invasive species,<ref name="ZhuEtAl">Template:Cite journal</ref><ref group="Ala" name="invasion-possible" /> but in December 2024, the species was announced to have been eradicated completely from the United States.<ref name="NYT2024">New York Times:Template:Cite web</ref>

Asian giant hornets prefer to live in low mountains and forests, while almost completely avoiding plains and high-altitude climates. V.Template:Nbsmandarinia creates nests by digging, co-opting pre-existing tunnels dug by rodents, or occupying spaces near rotten pine roots.<ref name="Yamane-1976" /><ref group="Arc" name="nest-location" /> It feeds primarily on larger insects, colonies of other eusocial insects, tree sap, and honey from honeybee colonies.<ref> Template:Cite web</ref> The hornet has a body length of Template:Convert, a wingspan around Template:Convert, and a stinger Template:Convert long, which injects a large amount of potent venom.<ref name="ngeo">Template:Cite web</ref>

Taxonomy and phylogeny

File:Vespa Mandarinia Magnifica - Filippo Turetta.jpg
form "magnifica"

V.Template:Nbsmandarinia is a species in the genus Vespa, which comprises all true hornets. Along with seven other species, V.Template:Nbsmandarinia is a part of the [[Vespa tropica|V.Template:Nbstropica]] species group, defined by the single notch located on the apical margin of the seventh gastral sternum of the male. The most closely related species within the species group is [[Vespa soror|V.Template:Nbssoror]].<ref group="Arc" name="soror-mandarinia" /><ref group="Arc" name="mandarinia-soror-only-color" /> The triangular shape of the apical margin of the clypeus of the female is diagnostic, the vertex of both species is enlarged, and the shape of the apex of the aedeagus is distinct and similar.<ref>Template:Cite journal</ref>

Division of the genus into subgenera has been attempted in the past,<ref>Template:Cite journal</ref> but has been abandoned, due to the anatomical similarity among species and because behavioral similarity is not associated with phylogeny.<ref name="Yamane-1976" /> The species has existed since the Miocene epoch, as indicated by fossils found in the Shanwang Formation.<ref>Template:Cite web</ref>

As of 2012, three subspecies were recognized:<ref>Template:Cite book</ref> V.Template:Nbsm.Template:Nbsmandarinia, V.Template:Nbsm.Template:Nbsmagnifica, and V.Template:Nbsm.Template:Nbsnobilis. The former subspecies referred to as V.Template:Nbsm.Template:Nbsjaponica has not been considered valid since 1997.<ref name = Carpenter>Template:Cite journal</ref> The most recent revision in 2020 eliminated all of the subspecies rankings entirely, with "japonica", "magnifica", and "nobilis" now relegated to informal non-taxonomic names for different color forms.<ref name="Vespa2020" />

Common names

After its discovery in North America, the scientific literature and official government sources referred to this species by its established common name, Asian giant hornet, whilst the mainstream media took to using the nickname "murder hornet".<ref name="Baker20202">Template:Cite news</ref><ref>Template:Cite web</ref><ref>Template:Cite web</ref> In July 2022, the Entomological Society of America stated that they will adopt the common name northern giant hornet for the species to avoid potentially discriminatory language, citing xenophobia and racism related to the COVID-19 pandemic.<ref name="ESA-NGH"> Template:Unbulleted list citebundle </ref><ref>Template:Cite web</ref><ref>Template:Cite web</ref><ref>Template:Cite web</ref>

Description

Head detail
File:Vespa mandarinia - kanagawa - 2024-10-14.webm
An Asian giant hornet takes flight in Kanagawa, Japan
Hornet specimen held in a human hand to illustrate its size

Regardless of sex, the hornet's head is a light shade of orange and its antennae are brown with a yellow-orange base. Its eyes and ocelli are dark brown to black. V.Template:Nbsmandarinia is distinguished from other hornets by its pronounced clypeus and large genae. Its orange mandible contains a black tooth that it uses for digging. The thorax is dark brown, with two grey wings varying in span from Template:Convert.<ref name="Barth"/>

Its forelegs are brighter than the mid- and hindlegs. The base of the forelegs is darker than the rest. The abdomen alternates between bands of dark brown or black, and a yellow-orange hue (consistent with its head color). The sixth segment is yellow. Its stinger is typically Template:Convert long and delivers a potent venom that in cases of multiple hornets stinging simultaneously, or by rare allergic reaction, can kill a human.<ref name="Barth"> Template:Cite web</ref>

Queens and workers

The queens are considerably larger than workers. Queens can exceed Template:Convert, while workers are between Template:Convert. The reproductive anatomy is consistent between the two, but workers do not reproduce.<ref name="Barth" />

Drones

Drones (males) are similar to females, and can attain Template:Convert in length, but lack stingers. This is a consistent feature among the Hymenoptera.<ref name="Barth" />

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Larvae

Larvae spin a silk cocoon when they complete development and are ready to pupate.<ref name="Kuroda-Kameda-2018" /> Larval silk proteins have a wide variety of potential applications due to their wide variety of potential morphologies, including the native fiber form, but also sponge, film, and gel.<ref name="Kuroda-Kameda-2018" />

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Genome

The mitochondrial genome is provided by Chen et al., 2015.<ref name = "mito" /> This information has also been important to confirm the place of the wider Vespidae family in the Vespoidea superfamily, and confirms that Vespoidea is monophyletic.<ref name = "mito" > 

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Misidentifications

Within two days of the initial 2020 news report on V.Template:Nbsmandarinia, insect identification centers in the Eastern United States (where the wasp has never occurred) began getting identification requests, and were swamped for the next several months, though not one of the thousands of submitted photos or samples was of V.Template:Nbsmandarinia, but were instead primarily wasps such as the European hornet (V.Template:Nbscrabro), the eastern cicada killer (Sphecius speciosus), or the southern yellowjacket (Vespula squamosa).<ref name="Skvarla">Michael J Skvarla, Matthew A Bertone, Patrick J Liesch (2022) Murder Hornet Mayhem: The Impact of the 2020 Giant Hornet Panic and COVID-19 Pandemic on Arthropod Identification Laboratories. American Entomologist 68(2): 38–43, https://doi.org/10.1093/ae/tmac029</ref><ref name="Lookalikes">Template:Cite web</ref>

Submissions suspected by laypeople to be V.Template:Nbsmandarinia also included other wasps of various sizes, bees, sawflies, horntails, wasp-mimicking flies, beetles, Jerusalem crickets, cicadas, and even a plastic children's toy that was wasp-like in appearance, all of which were routinely estimated to be 130–185% of their actual size.<ref name="Skvarla" />

Reports of this species from other parts of the world appear to be erroneous identifications of other introduced hornet species, such as [[Oriental hornet|V.Template:Nbsorientalis]] in several locations around the world, and [[Asian hornet|V.Template:Nbsvelutina]] in Europe.<ref>Template:Cite web</ref>

Distribution

Ecological distribution

V.Template:Nbsmandarinia is primarily a forest dweller.<ref name="Azmy-et-al-2016" /><ref name="Matsuura Sakagami 1973" /> When it does live in urban landscapes, it is highly associated with green space.<ref name="Azmy-et-al-2016" /><ref group="Ala" name="green-agree-Azmy" /> It is the most dependent upon green space of the Vespa species (with [[Vespa analis|V.Template:Nbsanalis]] the least). Extremely urbanized areas provide a refuge for V.Template:Nbsanalis, whereas V.Template:Nbsmandarinia – its predator – is entirely absent.<ref name="Azmy-et-al-2016" />

Geographic distribution

An Asian giant hornet

Asia

The Asian giant hornet can be found in:

North America

The first confirmed sightings of the Asian giant hornet in North America were confirmed in 2019 and were mainly concentrated in the Vancouver area, with nests also discovered in neighboring Whatcom County, Washington, in the United States. The last confirmed sightings were in 2021. 

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</ref> Further analysis determined that the nest had contained about 500 live specimens, including about 200 queens.<ref name=PressConf>Template:Cite web</ref><ref name=Nearly200>Template:Cite web</ref> Some of these specimens were sent to the Smithsonian Institution to become a part of the NMNH Biorepository permanent cryogenic collection.<ref name="Smithsonian-specimens">Template:Cite web</ref><ref name="KATU-cryogenic">Template:Cite web</ref> It was announced that several undiscovered live nests were also believed to exist within Washington State, because the captures of individual hornets in Birch, Blaine, and Custer were all relatively far from the discovered nest.<ref name=PressConf/><ref name=Nearly200/><ref name="BBC-more-nests-yet">Template:Cite web</ref> However, officials expressed cautious optimism, adding that eradicating the hornets before they became established in the area might still be possible. A Canadian official said that although individual specimens had been found in Canada and some nests were suspected to exist there, the hornets' presence seemed to be only in areas near the US-Canadian border, while the center of the invasion appeared to be in Washington.<ref name=PressConf/>

A mitochondrial DNA analysis was performed to determine the maternal population(s) ancestral to the British Columbia and Washington introduced populations.<ref group="Wil" name="mtDNA">p.Template:Spaces2, "Complete mitochondrial DNA was sequenced with Illumina’s MiSeq platform (ILLUMINA, United States)."</ref> The high dissimilarity between these two was similar to the mutual distances between each of the Chinese, Japanese, and Korean native populations<ref group="Wil" name="Jap-Kor-Chin-distance">p.Template:Spaces3, "These genetic differences corresponded to the values found between native V.Template:Nbsmandarinia from Japan, South Korea, and China."</ref> suggesting the specimens collected in 2019 were from two different maternal populations,<ref group="Wil" name="difference">p.Template:Spaces3-4, "A high pairwise distance of 0.0071 was also confirmed between the 13 PCGs of mitochondrial DNA sequences of V.Template:Nbsmandarinia specimens from the United States and Canada, suggesting that the hornets differ in maternal origin (Table 1). ... The ML tree also revealed that V.Template:Nbsmandarinia from the United States and Canada were not monophyletic (Fig. 2). Molecular phylogenetic analysis of the mitochondrial genomes revealed that V.Template:Nbsmandarinia from the United States was genetically distant from that of Canada. ... The observed genetic differences between the Canada and U.S. mitochondrial genomes suggest that the two V.Template:Nbsmandarinia specimens introduced to western N. America during or prior to 2019 are derived from different maternal lineages."</ref> Japanese in BC<ref group="Wil" name="Can-Japan">p.Template:Spaces4, "The mitochondrial genome of ... the Canadian V.Template:Nbsmandarinia was most genetically similar to the Japanese V.Template:Nbsmandarinia used in this study."</ref> and South Korean in Washington.<ref group="Wil" name="Blaine-Korea">p.Template:Spaces4, "The mitochondrial genome of the specimen collected from Blaine, WA shared 99.5% sequence homology to the specimen characterized from South Korea,"</ref> This suggests that two separate introductions of the Asian giant hornet occurred in North America within about Template:Convert of one another within a few months.

In April 2020, authorities in Washington asked members of the public to be alert and report any sightings of these hornets, which are expected to become active in April if they are in the area.<ref>Template:Cite news</ref> If they become established, the hornets "could decimate bee populations in the United States and establish such a deep presence that all hope for eradication could be lost." A "full-scale hunt" for the species by the WSDA was then underway.<ref name="Baker20202"/> Two assessment models of their potential to spread from their present location on the US–Canadian border suggested that they could spread northward into coastal British Columbia and Southeast Alaska, and southward as far as southern Oregon.<ref name="ZhuEtAl" /><ref group="Ala" name="PNW" /> The USDA's Agricultural Research Service is engaged in lure/attractant development and molecular genetics research, both as part of its normal research mission, but also to further the near-term eradication goal in Washington.<ref name="USDA-ARS-involved">Template:Cite web</ref>

In 2020, the United States Congress considered specific legislation to eradicate V.Template:Nbsmandarinia<ref name="Grijalva-proposed" /> including a proposal by the interior secretary, the Fish and Wildlife director, and the other relevant agencies, which has been introduced as an amendment to the appropriations omnibus.<ref name="US-omnibus-amendment-116HR133" /><ref name="US-propose-eradication-CNET" /> British Columbia Agriculture is prepared for a "long fight" lasting years, if necessary. One advantage humans will have is the lack of diversity of such an invasive population – leaving the hornets less prepared for novel environments and challenges.<ref name="BC-brace-Guardian" />

In June 2021, a dead, desiccated male was found near Marysville, Snohomish County, Washington, and reported to WSDA. Its different, more reddish color form immediately suggested yet another parental population from the Japanese and Korean ones already known. The USDA Animal and Plant Health Inspection Service performed a genetic analysis several days later, and together with WSDA, confirmed it was of a third, unrelated population. The discovery of a male in June is "perplexing" given that the earliest male emergence in 2020 was July, which was already earlier than normal for the home range. This and its desiccated state indicate it did not emerge in 2021 at all, but is instead a dead specimen that had already emerged in a previous year.<ref name="WSDA-third-intro-confirmed">Template:Cite web</ref>

The WSDA announced in December 2022 that "no confirmed sightings" of the hornet were reported in the state for that year,<ref name = "nothing-2022-KOMO" >Template:Cite news</ref> and in December 2023 stated no sightings occurred in 2023,<ref name="wsda 20231204">Template:Cite web</ref> and in December of 2024, WSDA declared that the hornets had been eradicated from North America.<ref name="NYT2024"/>

Nesting

V.Template:Nbsmandarinia nests in low mountain foothills and lowland forests.<ref name="Azmy-et-al-2016" /><ref group="Arc" name="nest-location" /> As a particularly dominant species, no efforts are directed toward conserving V.Template:Nbsmandarinia or its habitats, as they are common in areas of low human disturbance.<ref name="Azmy-et-al-2016" /> Unlike other species of Vespa, V.Template:Nbsmandarinia almost exclusively inhabits subterranean nests<ref name="Azmy-et-al-2016" /><ref group="Arc" name="nest-location" /> Template:Ndash in 1978, that aerial nests were unlikely, as Matsuura and Sakagami reported this to be unknown in Japan in 1973.<ref name="Akre-Davis-1978">Template:Cite journal</ref> and aerial nesting is still described as extremely rare in Japan,<ref name="Penn-State-Extension" /> and yet Template:As of all nests in the invasive range have been aerial.Template:Citation needed

In a study of 31 nests, 25 were found around rotten pine roots, and another study found only 9 of 56 nests above ground.<ref group="Arc" name="nest-location" /> Additionally, rodents, snakes, or other burrowing animals previously made some of the tunnels.<ref group="Arc" name="nest-location" /> The depth of these nests was between Template:Convert. The entrance at the ground surface varies in length from Template:Convert either horizontally, inclined, or vertically. The queens that found the nest prefer narrow cavities.<ref name="Matsuura Sakagami 1973">Template:Cite journal</ref>

Nests of V.Template:Nbsmandarinia typically lack a developed envelope. During the initial stages of development, the envelope is in an inverted-bowl shape.<ref group="Arc" name="nest-geometry" /> As the nest develops, one to three rough sheets of combs are created. Often, single primordial combs are created simultaneously and then fused into a single comb.<ref name="Matsuura Sakagami 1973" />

A system of one main pillar and secondary pillars connects the combs. Nests usually have four to seven combs.<ref group="Arc" name="nest-geometry" /> The top comb is abandoned after summer and left to rot. The largest comb is at the middle to bottom portion of the nest. The largest combs created by V.Template:Nbsmandarinia measured Template:Convert with 1,192 cells (no obstacles, circular) and Template:Convert (elliptical; wrapped around a root system).<ref name="Matsuura Sakagami 1973" />

Colony cycle

The nesting cycle of V.Template:Nbsmandarinia is fairly consistent with that of other eusocial insects. Six phases occur in each cycle.<ref name="Matsuura Sakagami 1973" />

Prenesting period

Inseminated and uninseminated queens enter hibernation following a cycle. They first appear in early to mid-April and begin feeding on the sap of Quercus (oak) trees. Although this timing is consistent among hornets, V.Template:Nbsmandarinia dominates the order, receiving preference for premium sap sources. Among the V.Template:Nbsmandarinia queens is a dominance hierarchy. The top-ranked queen begins feeding, while the other queens form a circle around her. Once the top queen finishes, the second-highest-ranking queen feeds. This process repeats until the last queen feeds at a poor hour.<ref name="Matsuura Sakagami 1973" />

Solitary, cooperative, and polyethic periods

Inseminated queens start to search for nesting sites in late April. The uninseminated queens do not search for nests, since their ovaries never fully develop. They continue to feed, but then disappear in early July.

An inseminated queen begins to create relatively small cells in which she raises around 40 small workers. Workers do not begin to work outside of the hive until July. Queens participate in activities outside the hive until mid-July, when they stay inside the nest and allow workers to do extranidal activities. Early August marks a fully developed nest, containing three combs holding 500 cells and 100 workers. After mid-September, no more eggs are laid and the focus shifts to caring for larvae. The queens die in late October.<ref name="Matsuura Sakagami 1973" />

Dissolution and hibernating period

File:Male Vespa mandarinia.DSC 1515.jpg
Male

Males and new queens take on their responsibilities in mid-September and mid-October, respectively. During this time, their body color becomes intense and the weights of the queens increase about 20%. Once the males and queens leave the nest, they do not return. In V.Template:Nbsmandarinia, males wait outside the nest entrance until the queens emerge, when males intercept them in midair, bring them to the ground, and copulate from 8 to 45 seconds. After this episode, the males return to the entrance for a second chance, while the now-mated queens leave to hibernate. Many queens (up to 65%) attempt to fight off the males and leave unfertilized,<ref name="Penn-State-Extension">Template:Cite web</ref> at least temporarily. After this episode, prehibernating queens are found in moist, subterranean habitats.

When sexed individuals emerge, workers shift their focus from protein and animal foods to carbohydrates. The last sexed individuals to emerge may die of starvation.<ref name="Matsuura Sakagami 1973"/>

Sting

The stinger of the Asian giant hornet is about Template:Convert long.<ref name="ngeo" /> Their stinger injects an especially potent venom that contains Template:Visible anchor.<ref name="Hirai-et-al-1981" /> Mastoparans are found in many bee and wasp venoms.<ref name="Hirai-et-al-1981" /> They are cytolytic peptides that can damage tissue by stimulating phospholipase action, in addition to its own phospholipase.<ref name="Hirai-et-al-1981"> 

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</ref><ref name="Matsuura Sakagami 1973" /> Masato Ono, an entomologist at Tamagawa University, described the sensation of being stung as feeling "like a hot nail being driven into my leg".<ref name="ngeo" /> Besides using their stingers to inject venom, Asian giant hornets are apparently able to spray venom into a person's eyes under certain circumstances, with one report in 2020 from Japan of long-term damage, though the exact extent of actual visual impairment still remains unassessed.<ref name="Hirano-2020">Template:Cite journal</ref>

The venom contains a neurotoxin called Template:Visible anchor,<ref name="Matsuura Sakagami 1973" /><ref group="Abe" name="mandaratoxin-exists" /> a single-chain polypeptide with a molecular weight around 20 kDa.<ref name="Matsuura Sakagami 1973" /><ref group="Abe" name="20-kDa" /> While a single wasp cannot inject a lethal dose, multiple stings can be lethal even to people who are not allergic if the dose is sufficient, and allergy to the venom greatly increases the risk of death. Tests involving mice found that the venom falls short of being the most lethal of all wasp venoms, having an Template:LD50 of 4.0Template:Spacesmg/kg. In comparison, the deadliest wasp venom (at least to laboratory mice) by weight belongs to [[Vespa luctuosa|V.Template:Nbsluctuosa]] at 1.6Template:Spacesmg/kg. The potency of the V.Template:Nbsmandarinia sting is due, rather, to the relatively large amount of venom injected.<ref name="hornet venom">Template:Cite journal</ref>

Immunogenicity

Evidence is insufficient to believe that prophylactic immunotherapy for the venom of other Vespidae will prevent allergic reaction to V.Template:Nbsmandarinia venom, because of wide differences in venom chemistry.<ref name="Pongracic-2020">Template:Cite web</ref>

Effects on humans

In 1957, van der Vecht was under the impression humans in the native range lived in constant fear of V.Template:Nbsmandarinia and Iwata reported in 1976 that research and removal were hampered by its attacks.<ref name="Akre-Davis-1978" />

Parasites

The strepsipteran Xenos moutoni is a common parasite among Vespa species. In a study of parasites among species of Vespa, 4.3% of V.Template:Nbsmandarinia females were parasitized. Males were not stylopized (parasitization by stylopid strepsipterans, such as X.Template:Nbsmoutoni) at all. The major consequence of being parasitized is the inability to reproduce, and stylopized queens follow the same fate as uninseminated queens. They do not search for an area to create a new colony and feed on sap until early July, when they disappear. In other species of Vespa, males also have a chance of being stylopized. The consequences between the two sexes are similar, as neither sex is able to reproduce.<ref>Template:Cite journal</ref>

Communication and perception

V.Template:Nbsmandarinia uses both visual and chemical cues as a means of navigating itself and others to the desired location. Scent marking was discussed as a way for hornets to direct other members of the colony to a food source. Even with antennae damage, V.Template:Nbsmandarinia was able to navigate itself. It was unable to find its destination only when vision impairment was induced. This implies that while chemical signaling is important, visual cues play an equally important role in guiding individuals. Other behaviors include the formation of a "royal court" consisting of workers that lick and bite the queen, thereby ingesting her pheromones.

These pheromones could directly communicate between the queen and her court or indirectly between her court and other workers due to the ingested pheromones. This is merely speculation, as no direct evidence has been collected to suggest the latter. V.Template:Nbsmandarinia communicates acoustically, as well. When larvae are hungry, they scrape their mandibles against the walls of the cell. Furthermore, adult hornets click their mandibles as a warning to other creatures that encroach upon their territories.<ref name="Barth" /><ref name="UWL">Template:Cite web</ref>

Scent marking

V.Template:Nbsmandarinia is the only species of social wasp known to apply a scent to direct its colony to a food source. The hornet secretes the chemical from the sixth sternal gland, also known as van der Vecht's gland. This behavior is observed during autumnal raids after the hornets begin hunting in groups instead of individually. The ability to apply scents may have arisen because the Asian giant hornet relies heavily on honey bee colonies as its main food source.<ref name="Taylor"/><ref name="Akre-Davis-1978" />

A single hornet is unable to take on an entire colony of honey bees because species such as Apis cerana have a well-organized defense mechanism. The honey bees swarm one wasp and vibrate their thoracic muscles to heat up the hornet and raise carbon dioxide to a lethal level. So, organized attacks are much more effective and easily devastate a colony of tens of thousands of honey bees.<ref name="Taylor">Template:Cite journal</ref><ref name="Akre-Davis-1978" />

Interspecies dominance

In an experiment observing four different species of Vespa (V.Template:Nbsducalis, V.Template:Nbscrabro, V.Template:Nbsanalis, and V.Template:Nbsmandarinia), V.Template:Nbsmandarinia was the dominant species. Multiple parameters were set to determine this. The first set parameter observed interaction-mediated departures, which are defined as scenarios wherein one species leaves its position due to the arrival of a more dominant individual. The proportion of interaction-mediated departures was the lowest for V.Template:Nbsmandarinia. Another measured parameter was attempted patch entry. Over the observed time, conspecifics (interactions with the same species) resulted in refused entry far more than heterospecifics (interactions with different species).<ref name="Yoshimoto"/>

Lastly, when feeding at sap flows, fights between these hornets, Pseudotorynorrhina japonica, Neope goschkevitschii, and Lethe sicelis were observed, and once more V.Template:Nbsmandarinia was the most dominant species. In 57 separate fights, one loss was observed to Neope goschkevitschii, giving V.Template:Nbsmandarinia a win rate of 98.3%. Based on interaction-mediated departures, attempted patch entry, and interspecific fights, V.Template:Nbsmandarinia is the most dominant Vespa species.<ref name="Yoshimoto">Template:Cite journal</ref>

Diet

File:Waspfeedingonmantis.jpg
Feeding on a mantis

The Asian giant hornet is intensely predatory; it hunts medium- to large-sized insects, such as bees,<ref name="Matsuura Sakagami 1973" /><ref name="Richter-2000">Template:Cite journal</ref> other hornet and wasp species, beetles, hornworms,<ref name="Adw: : Information">Template:Cite web</ref> and mantises. The latter are favored targets in late summer and fall. Large insects such as mantises are key protein sources to feed queen and drone larvae. Workers forage to feed their larvae, and since their prey can include crop pests, the hornets are sometimes regarded as beneficial.<ref name="Adw: : Information"/>

This hornet often attacks colonies of other Vespa species ([[Vespa simillima|V.Template:Nbssimillima]] being the usual prey species), Vespula species,<ref name="Adw: : Information"/> and honey bee (such as Apis cerana and A. mellifera)<ref name="Adw: : Information"/> hives to obtain the adults, pupae, and larvae as food for their own larvae. Sometimes, they cannibalize each other's colonies. A single scout, sometimes two or three, cautiously approaches the hive, producing pheromones to lead its nest-mates to the hive. The hornets can devastate a colony of honey bees, especially if it is the introduced western honey bee. A single hornet can kill as many as 40 bees per minute due to its large mandibles, which can quickly strike and decapitate prey.<ref name="Kosmeier">Template:Cite web</ref>

The honey bees' stings are ineffective because the hornets are five times their size and heavily armored. Only a few hornets (under 50) can exterminate a colony of tens of thousands of bees in a few hours. The hornets can fly up to Template:Convert in a single day, at speeds up to Template:Convert.<ref name="Kosmeier"/> The smaller Asian hornet similarly preys on honey bees, and has been spreading throughout Europe.

Hornet larvae, but not adults, can digest solid protein. The adult hornets can only drink the juices of their victims, and they chew their prey into a paste to feed to their larvae. The workers dismember the bodies of their prey to return only the most nutrient-rich body parts, such as flight muscles, to the nest.<ref name="Ross-9" /> Larvae of predatory social vespids generally, not just Vespa, secrete a clear liquid, sometimes referred to as Vespa amino acid mixture, the exact amino acid composition of which varies considerably from species to species, and which they produce to feed the adults on demand.<ref>Template:Cite journal</ref>

Native honey bees

[[File: honeybee thermal defence01.jpg|thumb|right|A defensive ball of Japanese honey bees (A. c. japonica) in which two Japanese hornets ([[Vespa simillima xanthoptera|V.Template:Nbssimillima xanthoptera]]) are engulfed, incapacitated, heated, and eventually killed. This sort of defense is also used against the Asian giant hornet.]]

Beekeepers in Japan attempted to introduce western honey bees (Apis mellifera) because of their high productivity. Western honey bees have no innate defense against the hornets, which can rapidly destroy their colonies.<ref name=Ross-9 /> Kakugo virus infection, though, may provide an extrinsic defence.<ref name="Hamblin-et-al-2014">Template:Cite journal</ref> Although a handful of Asian giant hornets can easily defeat the uncoordinated defenses of a western honey bee colony, the Japanese honey bee (Apis cerana japonica) has an effective strategy. When a hornet scout locates and approaches a Japanese honey bee hive, she emits specific pheromonal hunting signals. When the Japanese honey bees detect these pheromones, 100 or so gather near the entrance of the nest and set up a trap, keeping the entrance open.<ref name="Balling" />

This permits the hornet to enter the hive. As the hornet enters, a mob of hundreds of bees surrounds it in a ball, completely covering it and preventing it from reacting effectively. The bees violently vibrate their flight muscles in much the same way as they do to heat the hive in cold conditions.<ref name="Balling" /> This raises the temperature in the ball to the critical temperature of Template:Convert.<ref name="Balling" />

In addition, the exertions of the honey bees raise the level of carbon dioxide (CO2) in the ball.<ref name="Balling" /> The bees can tolerate up to Template:Convert even at that concentration of CO2, but the hornet cannot survive the combination of high temperature and high carbon dioxide level.<ref name="Balling"> 

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</ref> Some honey bees do die along with the intruder, much as happens when they attack other intruders with their stings, but by killing the hornet scout, they prevent it from summoning reinforcements that would wipe out the entire colony.<ref>Template:Cite web</ref>

Detailed research suggests this account of the behavior of the honey bees and a few species of hornets is incomplete and that the honey bees and the predators are developing strategies to avoid expensive and mutually unprofitable conflict. Instead, when honey bees detect scouting hornets, they transmit an "I see you" signal that commonly warns off the predator.<ref>Template:Cite journal</ref> Another defence used by Apis cerana is speeding up dramatically when returning to the colony, to avoid midair attacks.Template:Citation needed

Diet in North America

Based on an examination of larval waste products, the Washington State Department of Agriculture determined that the prey of V.Template:Nbsmandarinia included cluster fly, orange legged drone fly, bristle fly, bronze birch borer beetle, western honey bee, western yellowjacket, German yellowjacket, aerial yellowjacket, bald faced hornet, European paper wasp, golden paper wasp, paddle-tailed darner dragonfly, shadow darner dragonfly, large yellow underwing moth, blinded sphinx moth, and red admiral butterfly (Vanessa atalanta). They had also eaten cow's meat, but the WSDA suggests that this may have been beef from a hamburger.<ref name="WSDA-frass">Template:Cite web</ref>

Predators

The Asian giant hornet has very few natural predators. However, V.Template:Nbsmandarinia nests are attacked by conspecific colonies, and crested honey buzzards may prey on this hornet.<ref>Template:Cite web</ref> Besides the honey buzzard and each other, there are also instances of other insects such as mantises killing Asian giant hornets.<ref>Template:Cite web</ref>

Pollination capability

V.Template:Nbsmandarinia is not solely carnivorous, but also a pollinator. It is among the diurnal pollinators of the obligate plant parasite Mitrastemon yamamotoi.<ref name="Suetsugu-2018">Template:Cite journal</ref> It is among the most common pollinators of Musella lasiocarpa in the Yunnan Province of China.<ref name = "Pollinator" > Template:Unbulleted list citebundle </ref>

Extermination methods

As of 1973, six different methods were used to control hornets in Japan; these methods decrease damage done by V.Template:Nbsmandarinia.Template:Citation needed

Beating

Hornets are crushed with wooden sticks with flat heads. Hornets do not counterattack when they are in the bee-hunting phase or the hive-attack phase ("slaughter"), but they aggressively guard a beehive once they kill the defenders and occupy it. The biggest expenditure in this method is time, as the process is inefficient.<ref name="Matsuura Sakagami 1973" />

Nest removal

Applying poisons or fires at night is an effective way of exterminating a colony. The most difficult part about this tactic is finding the subterranean nests. The most common method of discovering nests is giving a piece of frog or fish meat attached to a cotton ball to a wasp and following it back to its nest. With V.Template:Nbsmandarinia, this is particularly difficult considering its common home flight radius of Template:Convert. V.Template:Nbsmandarinia travels up to Template:Convert away from the nest.<ref name="Matsuura Sakagami 1973" /><ref name="WiredMurderHornet">Template:Cite magazine</ref>

For the rare nest that is up in a tree, wrapping the tree in plastic and vacuuming the hornets out is used.<ref name="WSDA-Blog-removal"/>

Bait traps

Bait traps can be placed in apiaries. The system consists of multiple compartments that direct the hornet into a one-sided hole which is difficult to return through once it is in the cul-de-sac compartment, an area located at the top of the box from which honey bees can escape through a mesh opening, but wasps cannot due to their large size. Baits used to attract the hornets include a diluted millet jelly solution or a crude sugar solution with a mixture of intoxicants, vinegar, or fruit essence.<ref name="Matsuura Sakagami 1973" />

The WSDA has been using plastic bottle traps, baited with fruit juice and added alcohol. The alcohol is used because it repels bees, but not V.Template:Nbsmandarinia, thus reducing the bycatch.<ref name="Discover-mag-2020" />

Mass poisoning

Hornets at the apiary are captured and fed a sugar solution or bee that has been poisoned with malathion. The toxin is expected to spread through trophallaxis. This method is good in principle, but has not been tested extensively.<ref name="Matsuura Sakagami 1973" />

Trapping at hive entrances

The trap is attached to the front of beehives. The effectiveness of the trap is determined by its ability to capture hornets while allowing honey bees to escape easily. The hornet enters the trap and catches a bee. When it tries to fly back through the entrance of the hive, it hits the front of the trap. The hornet flies upwards to escape and enters the capture chamber, where the hornets are left to die. Some hornets find a way to escape the trap through the front, so these traps can be very inefficient.<ref name="Matsuura Sakagami 1973" />

Protective screens

As explained in the trapping section, if met by resistance, hornets lose the urge to attack and instead retreat. Different measures of resistance include weeds, wire, or fishing nets or limiting the passage size so only honey bees can make it through. Experienced hornets catch on and eventually stay on these traps, awaiting the arrival of bees. The best method of controlling hornets is to combine protective screens with traps.<ref name="Matsuura Sakagami 1973" />

Glue traps

Some Japanese beekeepers place glue traps, similar to the ones commonly used against mice, atop the bees' artificial nesting box with a disarmed giant hornet stuck to the glue. The struggling hornet attracts more hornets who try to help and then get trapped on the glue sheet.<ref>Template:Cite web</ref>

Human consumption

File:オオスズメバチの幼虫.jpg
Hornet larva

In some Japanese mountain villages, the nests are excavated and the larvae are considered a delicacy when fried.<ref name="Ross-9" /> In the central Chūbu region, these wasps are sometimes eaten as snacks or an ingredient in drinks. The grubs are often preserved in jars, pan-fried or steamed with rice to make a savory dish called hebo-gohan or hebo-meshi (へぼ飯).<ref>Template:Cite web</ref> The adults are fried on skewers with the stinger still attached until the body becomes crunchy.<ref>Template:Cite news</ref> Within this region, historically residents would hunt for wasp nests as a social activity, fostering the practice of wasp harvesting as well as establishing it as cultural heritage, celebrated in the Kushihara Hebo Matsuri, a festival celebrating wasp-based cuisine.<ref>Template:Cite web</ref>

Asian giant hornets are also cultivated in Nagaland and Manipur, in eastern India.<ref>https://www.researchgate.net/publication/354251865_Traditional_rearing_techniques_of_the_edible_Asian_giant_hornet_Vespa_mandarinia_Smith_and_its_socio-economic_perspective_in_Nagaland_India</ref><ref>Template:Cite web</ref>

Potential economic impact

If V.Template:Nbsmandarinia were to settle all suitable habitats in North America, potential control costs in the United States would be over US$113.7 million/year (possibly significantly higher).<ref group="Ala" name="113mill" /> Washington was the only state with confirmed sightings, and there were no confirmed sightings in Washington after 2021, and is now considered extirpated.<ref name="NYT2024"/>

If V.Template:Nbsmandarinia were to reach all suitable habitats in North America, bee products would bring in US$11.98 ± 0.64 million less per year, and bee-pollinated crops would produce US$101.8 million less per year.<ref group="Ala" name="102mill" /> New York, Massachusetts, Pennsylvania, Connecticut, North Carolina, New Jersey, and Virginia would be most severely affected.<ref group="Ala" name="worst-states" /> By region, New England would be worst hit, and to a lesser degree the entire northeast and the entirety of eastern North America.<ref group="Ala" name="worst-states" /> New England would potentially become by far the greatest concentration of V.Template:Nbsmandarinia in the world, far surpassing the original introduction site (the Pacific Northwest), and even its home range of East Asia.<ref group="Ala" name="worst-states" /> Alfalfa / other hays, apples, grapes, tobacco, cotton, and blueberries would be the crops most severely affected.<ref group="Ala" name="worst-crops" />

See also

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References

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Further information

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