''Vespula infernalis'' is an obligate parasitic wasp, parasitizing the nests of other species in the genus ''

Vespula ''Vespula'' is a small genus of social wasps, widely distributed in the Northern Hemisphere. Along with members of their sister genus ''Dolichovespula'', they are collectively known by the common name yellowjackets (or yellow jackets) in North ...

''. Its common host species is '' V. acadica'' in North America. It is sometimes called the cuckoo yellowjacket wasp due to its

inquiline In zoology, an inquiline (from Latin ''inquilinus'', "lodger" or "tenant") is an animal that lives commensally in the nest, burrow, or dwelling place of an animal of another species. For example, some organisms such as insects may live in the h ...

lifestyle. They differ from other parasitic wasps in their intensely

aggressive Aggression is overt or covert, often harmful, social interaction with the intention of inflicting damage or other harm upon another individual; although it can be channeled into creative and practical outlets for some. It may occur either reacti ...

behaviour during invasion and occupation of the host colony. Several morphological adaptations such as bigger body parts and more curved

sting Sting may refer to: * Stinger or sting, a structure of an animal to inject venom, or the injury produced by a stinger * Irritating hairs or prickles of a stinging plant, or the plant itself Fictional characters and entities * Sting (Middle-eart ...

shafts are observed in these wasps to aid their aggressive parasitic behaviour. Once they occupy a host's nest, ''V. infernalis'' are known to engage in mauling and chasing of host workers and forced

trophallaxis Trophallaxis () is the transfer of food or other fluids among members of a community through mouth-to-mouth ( stomodeal) or anus-to-mouth ( proctodeal) feeding. Along with nutrients, trophallaxis can involve the transfer of molecules such as pher ...

. Female wasps will also force host workers to feed and take care of their brood .

Taxonomy and phylogeny

''Vespula infernalis'' is a member of the family

Vespidae The Vespidae are a large (nearly 5000 species), diverse, cosmopolitan family of wasps, including nearly all the known eusocial wasps (such as ''Polistes fuscatus'', ''Vespa orientalis'', and ''Vespula germanica'') and many solitary wasps. Each ...

. Furthermore, ''Vespula infernalis'' is nearly identical in appearance and biology to the

Old World The "Old World" is a term for Afro-Eurasia that originated in Europe , after Europeans became aware of the existence of the Americas. It is used to contrast the continents of Africa, Europe, and Asia, which were previously thought of by the ...

species '' V. austriaca'' and is considered its sister species. Until recently the Nearctic population was considered to be the same species, and appears in all of the literature before 2012 as ''V. austriaca'',
BugGuide - ''Vespula infernalis'' though some sources are not yet updated (e.g.).

Description and identification

This wasp is an obligate parasite, obligate social parasite. As a result, it possess special morphological adaptations to take over host colonies. These adaptations include larger body parts such as a larger head width than its host ''

Vespula acadica ''Vespula acadica,'' also known as the Forest Yellowjacket, is a North American species of eusocial wasp which is part of the ''"rufa"'' group within the genus ''Vespula''. It is a black and yellow wasp that is found in arboreal areas and builds ...

''. Because of its parasitic lifestyle, ''V. infernalis'' has a large

stinger A stinger (or sting) is a sharp organ found in various animals (typically insects and other arthropods) capable of injecting venom, usually by piercing the epidermis of another animal. An insect sting is complicated by its introduction of v ...

with very curved sting shafts; this curving allows the parasitic wasp to puncture through the intersegmental membranes of host colony workers who are defending their nests. The male

abdomen The abdomen (colloquially called the belly, tummy, midriff, tucky or stomach) is the part of the body between the thorax (chest) and pelvis, in humans and in other vertebrates. The abdomen is the front part of the abdominal segment of the torso. ...

is longer with thick

lateral Lateral is a geometric term of location which may refer to: Healthcare *Lateral (anatomy), an anatomical direction *Lateral cricoarytenoid muscle *Lateral release (surgery), a surgical procedure on the side of a kneecap Phonetics *Lateral cons ...

black bands while the female abdomen is wider with fewer lateral black bands and black dots. ''V. infernalis'' wasps have a characteristic black and yellow colouring throughout their bodies. Irregular margins and narrow yellow marks on the scape are often used to identify ''Vespula infernalis''.

Distribution and habitat

''Vespula infernalis'' is found in the

Nearctic The Nearctic realm is one of the eight biogeographic realms constituting the Earth's land surface. The Nearctic realm covers most of North America, including Greenland, Central Florida, and the highlands of Mexico. The parts of North America t ...

region, in the

Boreal Boreal may refer to: Climatology and geography *Boreal (age), the first climatic phase of the Blytt-Sernander sequence of northern Europe, during the Holocene epoch *Boreal climate, a climate characterized by long winters and short, cool to mild ...

region of

North America North America is a continent in the Northern Hemisphere and almost entirely within the Western Hemisphere. It is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South America and the Car ...

. The species is not considered rare and is stable throughout its range. These wasps are seen throughout all the provinces and territories of

Canada Canada is a country in North America. Its ten provinces and three territories extend from the Atlantic Ocean to the Pacific Ocean and northward into the Arctic Ocean, covering over , making it the world's second-largest country by tot ...

and in certain states in the

United States The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country primarily located in North America. It consists of 50 states, a federal district, five major unincorporated territorie ...

; Alaska, New Jersey, Michigan, Wisconsin, North Dakota, New Mexico, Arizona, and California.

Colony cycle

This wasp is known as a social parasite. Their life cycle depends on invading and usurping other wasps' colonies. As an

obligate parasite An obligate parasite or holoparasite is a parasitic organism that cannot complete its life-cycle without exploiting a suitable host. If an obligate parasite cannot obtain a host it will fail to reproduce. This is opposed to a facultative parasite, ...

, ''Vespula infernalis'' lacks a worker caste and cannot build their own nests or feed their own offspring.Reed, H.C., Akre R.D. (1983). Colony behavior of the obligate social parasite ''Vespula austriaca'' (Panzer) (Hymenoptera Vespidae). ''Insectes Sociaux'' 30(3):259–273. ''V. infernalis'' females will

hibernate Hibernation is a state of minimal activity and metabolic depression undergone by some animal species. Hibernation is a seasonal heterothermy characterized by low body-temperature, slow breathing and heart-rate, and low metabolic rate. It most ...

longer than their host queens, ensuring that the hosts' nests will be ready when they leave their hibernation spots.Reed, H.C., Akre R.D. (1983). Usurpation behavior of the Yellowjacket Social Parasite ''Vespula austriaca'' (Panzer) (Hymenoptera: Vespidae). ''The American Midland Naturalist'' 110(2):419–432. After killing the host queen, the female ''V. infernalis'' tends to be aggressive towards the host workers who rear her brood.Reed, H.C., Akre R.D, and Garnett, W.B. (1979). A North American Host of the Yellowjacket Social Parasite ''Vespula austriaca'' (Panzer) (Hymenoptera: Vespidae). ''Entomological News'' 90(2):110–113. These wasps have very short seasons with flight periods from June to mid July and August to mid September.

Parasitic behaviour

''Vespula infernalis''

parasitise Parasitism is a close relationship between species, where one organism, the parasite, lives on or inside another organism, the host, causing it some harm, and is adapted structurally to this way of life. The entomologist E. O. Wilson has ...

s ''

''. Near the

dorsal Dorsal (from Latin ''dorsum'' ‘back’) may refer to: * Dorsal (anatomy), an anatomical term of location referring to the back or upper side of an organism or parts of an organism * Dorsal, positioned on top of an aircraft's fuselage * Dorsal co ...

edge of ''V. infernalis'' mandibles, there is a fourth marginal tooth whereas the host, ''V. acadica'' has three. When researchers dissected individuals of ''V. infernalis'', they found that they had larger, sturdier mature muscle bundles in abdominal sterna and

tergum A ''tergum'' (Latin for "the back"; plural ''terga'', associated adjective tergal) is the Anatomical terms of location#Dorsal and ventral, dorsal ('upper') portion of an arthropod segment other than the head. The Anatomical terms of location#Ante ...

than the muscles in a queen of ''V. acadica''. As a result, it was more difficult to dissect ''V. infernalis''. Nests of ''V. acadica'' were found to be smaller than normal due to the parasitism of ''V. infernalis''.

Invasion

Queen-reared worker stage

When a female ''V. infernalis'' invades a host's nest such as ''

''during the queen-reared worker stage, the usurpation can be divided into two phases. The first phase is preusurpation. During this phase, interactions between the intruder and the host queen could be relatively calm and civil or aggressive. The queen may ignore the intruder and refrain from firing an attack first. Likewise, the workers exhibit a similar behaviour like their queen. But if the intruder attacks first by mauling or attempting to sting a worker, interactions between the queen and intruder become intense. The parasite, if successful, will use its stinger to paralyze the head,

thorax The thorax or chest is a part of the anatomy of humans, mammals, and other tetrapod animals located between the neck and the abdomen. In insects, crustaceans, and the extinct trilobites, the thorax is one of the three main divisions of the cre ...

, and legs of the host queen. This stage is considered the most vulnerable and hence, the most popular time to invade. It is susceptible to invasion because both the queen and workers are less defensive.

Post-emergence colony stage

During this stage, the colony is larger. In one experiment, a ''Vespula infernalis'' female was allowed to invade a ''

Vespula atropilosa ''Vespula atropilosa'', also known as the prairie yellowjacket, is a black and yellow social wasp that forms annual colonies. ''Vespula atropilosa'' was formerly a member of the '' Vespa'' family. Males have either xanthic (yellow) or melanic ( ...

'' colony. Different from the queen reared worker stage, the workers in this stage were much more defensive; more aggression was observed in the form of stinging, mauling and chasing. Additionally, the parasite displays more aggression than the host's queen. During a fight between the parasite and the queen, the parasite will do anything to harm or gain a better position by using her mandibles and stinger. Injuries to the queen include but are not limited to broken antennae and injured fore and hind-leg. Surprisingly, the host queen refrained from using her

mandibles In anatomy, the mandible, lower jaw or jawbone is the largest, strongest and lowest bone in the human facial skeleton. It forms the lower jaw and holds the lower tooth, teeth in place. The mandible sits beneath the maxilla. It is the only movabl ...

whereas the workers were quick to use theirs in defense.

Post-invasion: parasite and host worker interactions

''Vespula infernalis'' are very hostile and aggressive in invading and killing or driving away the host queen. Once the invasion of a host nest is successful, ''V. infernalis'' will take over the nest, inspecting and patrolling the cells. The host workers will initially avoid the parasite and often ignore any colony duties. In response, the parasite will maul and chase the workers. While there is still tension, the inquiline typically does not sting the workers and does not engage in egg eating (

oophagy Oophagy ( ) sometimes ovophagy, literally "egg eating", is the practice of embryos feeding on eggs produced by the ovary while still inside the mother's uterus. The word oophagy is formed from the classical Greek (, "egg") and classical Greek (, ...

). A suggested strategy may be to kill older workers of the host colony first and leave the younger workers behind to take care of the brood. During this period, a female will assert her dominance over the younger workers. This obvious display of dominance by the parasite over the host workers is more common during early colony occupations and absent later on. The parasite displays mauling behaviour: it grabs the workers with its legs and chews on their dorsums. Furthermore, the parasite also displays mauling behaviour after

, which it initiates by soliciting and chasing a worker. ''Vespula infernalis'' rarely

forage Forage is a plant material (mainly plant leaves and stems) eaten by grazing livestock. Historically, the term ''forage'' has meant only plants eaten by the animals directly as pasture, crop residue, or immature cereal crops, but it is also used m ...

, build cells, or feed

larvae A larva (; plural larvae ) is a distinct juvenile form many animals undergo before metamorphosis into adults. Animals with indirect development such as insects, amphibians, or cnidarians typically have a larval phase of their life cycle. The ...

, nor do they help thermoregulate (workers fan during hot temperatures or adopt warming postures during low temperatures). Furthermore, even when a nest is attacked by enemies, the parasite will remain inside the nest rather than help the workers defend it.

Suppression of reproduction of host workers

Several signs indicate that ''Vespula infernalis'' repress the reproduction of host workers. There is no worker oviposition in nests of ''Vespula acadica'' parasitised by ''Vespula infernalis''. Secondly, if workers were ovipositing then there would be higher levels of aggression between workers. However mauling was reduced between workers. The frequent aggressive and assertive behaviours of the parasites aid in asserting reproductive monopoly. Another indication is that parasites are observed to patrol cells frequently, hence defending

oviposition The ovipositor is a tube-like organ used by some animals, especially insects, for the laying of eggs. In insects, an ovipositor consists of a maximum of three pairs of appendages. The details and morphology of the ovipositor vary, but typical ...

sites. Lastly, during gastral dragging (dragging of abdomen across comb), substances that prevent

oogenesis Oogenesis, ovogenesis, or oögenesis is the differentiation of the ovum (egg cell) into a cell competent to further develop when fertilized. It is developed from the primary oocyte by maturation. Oogenesis is initiated in the embryonic stage. O ...

in workers are released from the

Dufour's gland Dufour's gland is an abdominal gland of certain insects, part of the anatomy of the ovipositor or sting apparatus in female members of Apocrita. The diversification of Hymenoptera took place in the Cretaceous and the gland may have developed at a ...

of the parasite.

Diet

While other wasp queens depend on secretions from

for food, ''Vespula infernalis'' obtain their nourishment in the liquid form through solicitations and

of host workers. They rarely solicit larvae for nourishment. The parasites will often use force to obtain what they need. During forced feeding, the parasite will grab the host worker using its

forelegs A forelimb or front limb is one of the paired articulated appendages (limbs) attached on the cranial (anterior) end of a terrestrial tetrapod vertebrate's torso. With reference to quadrupeds, the term foreleg or front leg is often used instead. ...

to reel in the worker. More forceful behaviour includes pushing the host worker against a comb of the nest. While some parasitic behaviour (i.e. maulings) only occurs during early post-invasion stages, forced

behaviour occurs throughout. Towards the later stages, the intensity of forced feeding declined, leading to host workers escaping forced encounters. Usually forced trophallaxis encounters were short lasting from 1–5 seconds. But some encounters lasted for as long as 43 seconds.

Characteristics of the venom

Due to the parasitic lifestyle of ''Vespula infernalis'', the sting is a vital apparatus. It consists of the shaft, aculeus,

, and the venom glands. The Dufour's gland and venom reservoirs are the biggest among ''Vespula infernalis'' females. In an experiment where the oily venom extracted from ''V. infernalis'' was injected into ''

Vespula pensylvanica ''Vespula pensylvanica'', the western yellowjacket, is a Nearctic species of wasp in the genus ''Vespula''.Akre, Roger D., Albert Greene, John F. MacDonald, Peter J. Landolt, and Harry G. Davis. Agricultural Handbook Number 552. United States Dep ...

'' workers, the

lethality Lethality (also called deadliness or perniciousness) is how capable something is of causing death. Most often it is used when referring to diseases, chemical weapons, biological weapons, or their toxic chemical components. The use of this ter ...

(LD50) value was between 20 and 30 mg/kg. '' V. pensylvanica'' queens had a higher tolerance to ''V. infernalis'' venom than workers (LD50=81 mg/kg). On average, it took 18.6 μg of venom to kill about half of the queens and 2–3 μg of venom to kill half the workers. The venom has the ability to paralyze and impair activities such as flying. Material obtained from the Dufour's gland was also injected into '' V. pensylvanica'' wasps; no significant effects were observed, indicating the gland does not contain a poison. Generally, in order to kill a host worker, a ''V. infernalis'' has to use about a third of its venom supply. More venom is needed to kill a queen. Surprisingly, ''V. infernalis'' venom is as lethal as the venom from ''V. atropilosa'' and ''V. pensylvanica''.

Reproduction

In preusurpation ''V. infernalis'' individuals, Dufour's gland contains clear oily material. It is part of the reproductive organs along with the

ovaries The ovary is an organ in the female reproductive system that produces an ovum. When released, this travels down the fallopian tube into the uterus, where it may become fertilized by a sperm. There is an ovary () found on each side of the body. T ...

and a poison gland. Distinctly enough, in new fall wasps, the Dufour's gland was empty and flat and in older wasps, the gland had a little oil but was flat as well.

Hypertrophy Hypertrophy is the increase in the volume of an organ or tissue due to the enlargement of its component cells. It is distinguished from hyperplasia, in which the cells remain approximately the same size but increase in number.Updated by Linda J ...

of the

is known to occur but more evidence is needed. During and after the mauling period, female ''Vespula infernalis'' will oviposit. This time period is brief. The females insert eggs in new cell combs. Workers act no differently during period of

. However, one instance of a worker interrupting the oviposition of the parasite was recorded, which led to mauling of the worker by the parasite and the egg falling out of the designated cell. Eggs laid by ''Vespula infernalis'' are not only found in cells but also found on the cell wall, exterior of the comb, between cells, or along the caps.

References

{{Taxonbar, from=Q97355600 Hymenoptera of North America Vespidae Insects described in 1854