Jack jumper ant

the ant Myrmecia pilosula
Species of ant endemic to Australia

The jack jumper ant (Myrmecia pilosula), also known as the jack jumper, jumping jack, hopper ant, or jumper ant, is a species of venomous ant native to Australia. Most frequently found in Tasmania and southeast mainland Australia, it is a member of the genus Myrmecia, subfamily Myrmeciinae, and was formally described and named by British entomologist Frederick Smith in 1858. This species is known for its ability to jump long distances. These ants are large; workers and males are about the same size: for workers, and for males. The queen measures roughly long and is similar in appearance to workers, whereas males are identifiable by their perceptibly smaller mandibles. Jack jumper ants are primarily active during the day and live in open habitats, nesting in bushland, woodlands, and dry open forests, surrounded by gravel and sandy soil, which can be found in rural areas and are less common in urban areas. They prey on small insects and use their barbless stingers to kill other insects by injecting venom. Other ants and predatory invertebrates prey on the jack jumper ant. The average worker has a life expectancy of over one year. Workers are gamergates, allowing them to reproduce with drones, whether or not a queen is present in the colony. The ant is a part of the Myrmecia pilosula species complex; this ant and other members of the complex are known to have a single pair of chromosomes. Their sting generally only causes a mild local reaction in humans; however, it is one of the few ant species that can be dangerous to humans, along with other ants in the genus Myrmecia. The ant venom is particularly immunogenic for an insect venom; the venom causes about 90% of Australian ant allergies. In endemic areas, up to 3% of the human population has developed an allergy to the venom and about half of these allergic people can suffer from anaphylactic reactions (increased heart rate, falling blood pressure, and other symptoms), which can lead to death on rare occasions. Between 1980 and 2000, four deaths were due to anaphylaxis from jack jumper stings, all of them in Tasmania. Individuals prone to severe allergic reactions caused by the ant's sting can be treated with allergen immunotherapy (desensitisation).

The specific name derives from the Latin word pilosa, meaning 'covered with soft hair'. The ant was first identified in 1858 by British entomologist Frederick Smith in his Catalogue of hymenopterous insects in the collection of the British Museum part VI, under the binomial name Myrmecia pilosula from specimens he collected in Hobart in Tasmania. There, Smith described the specimens of a worker, queen, and male. The type specimen is located in the British Museum in London. and placed the ant in the subgenus in 1943. William Brown synonymised Promyrmecia due to the lack of morphological evidence that would make it distinct from Myrmecia and later placed the jack jumper ant in the genus in 1953. One synonym for the species has been published – Ponera ruginoda (also titled Myrmecia ruginoda), described by Smith in the same work, and a male holotype specimen was originally described for this synonym. but it was later classified as a junior synonym of the jack jumper ant, after specimens of each were compared. The M. pilosula species complex was first defined by Italian entomologist Carlo Emery. Members of this group include M. apicalis, M. chasei, M. chrysogaster, M. croslandi, M. cydista, M. dispar, M. elegans, M. harderi, M. ludlowi, M. michaelseni, M. occidentalis M. queenslandica, M. rugosa, and M. varians. Additional species that were described in this group in 2015 include M. banksi, M. haskinsorum, M. imaii, and M. impaternata. Their characteristic jumping motion when agitated or foraging inspires the common name "jack jumper", a behaviour also shared with other Myrmecia ants, such as M. nigrocincta. "jumping ant", It is also named after the jumping jack firecracker.

Like its relatives, the ant possesses a powerful sting and large mandibles. These ants can be black or blackish red in colour, and may have yellow or orange legs. The ant is medium sized in comparison to other Myrmecia species, where workers are typically long. Excluding mandibles, jack jumpers measure in length. The ant's antennae, tibiae, tarsi, and mandibles are also yellow or orange. The ants can be found in the south western tip of Western Australia, where it has been seen in the sand hills around Albany, Mundaring, Denmark and Esperance. However, populations have been collected from the suburb of Elsternwick, and they are commonly found in the Great Otway Ranges, with many nests observed around Gellibrand. In New South Wales, nests are found throughout the entire state (with the exception of north western New South Wales), but dense populations are mostly found in the Snowy Mountains, Blue Mountains and coastal regions. Jack jumper ants live in open habitats, such as damp areas, forests, pastures, gardens, and lawns, preferring fine gravel and sandy soil. Colonies can also be spotted around light bushland. Their preferred natural habitats include woodlands, dry open forests, grasslands, and rural areas, and less common in urban areas. Their nests are mounds built from finely granular gravel, soil, and pebbles, measuring in diameter and can be as tall as 0.5 m (20 in) in height. Two types of nests for this species have been described, one being a simple nest with a noticeable shaft inside, the other being a complex structure surrounded by a mound. Their range in southern Australia, like other regional ant species, appears like that of a relict ant. Jack jumpers have been found in dry sclerophyll forests, at elevations ranging from , averaging Rove beetles in the genus Heterothops generally thrive in jack jumper nests and raise their brood within their chambers, and skinks have been found in some nests. Populations are dense in the higher mountain regions of Tasmania. The ant prefers rural areas, found in warm, dry, open eucalypt woodlands; the climate provides the ant with isolation and warmth. This environment also produces the ant's food, which includes nectar and invertebrate prey. In suburban areas, this ant is found in native vegetation, and uses rockeries, cracks in concrete walls, dry soil, and grass to build nests. One study found suburbs with voluminous vegetation cover such as Mount Nelson, Fern Tree and West Hobart host jack jumper populations, while the heavily urbanised suburbs of North Hobart and Battery Point, do not. Pest control of the jack jumper ant is successful in maintaining their populations around suburban habitats. Chemicals such as bendiocarb, chlorpyrifos, diazinon, and permethrin are effective against them. Spraying of Solfac into nests is an effective way of controlling nests if they are in a close range of areas with considerable amounts of congestion and human activity. Pouring carbon disulfide into nest holes and covering entrances up with soil is another method of removing colonies. The Australian National Botanic Gardens have an effective strategy of marking and maintaining jack jumper nests. He further wrote that they also made a ludicrous appearance as they emerge from their nests, in a series of short hops. While no studies have established whether or not these ants contain alarm pheromones, their relative Myrmecia gulosa is capable of inducing territorial alarm using pheromones. If proven, this would explain their ability to attack en masse. Foraging workers are regularly observed on the inflorescences of Prasophyllum alpinum (mostly pollinated by wasps of the subfamily Ichneumonidae). Although pollinia are often seen in the ants' jaws, they have a habit of cleaning their mandibles on the leaves and stems of nectar rich plants before moving on, preventing pollen exchange. Like other bull ants, they are solitary when they forage, but only workers perform this role. These ants are omnivores Jack jumpers have smooth stingers, thus can sting indefinitely. Jack jumper ants are skilled hunters, partially due to their excellent vision; they can even kill and devour wasps and bees. They also kill and eat other ants, such as carpenter ants (Camponotus) The ants have been observed to run and leap energetically at flies when they land, particularly on Acacia shrubs, plants, or trees. Jack jumpers and other Myrmecia ants prey on insects such as cockroaches and crickets. Mature adult ants of this species mostly eat sweet substances, so dead insects they find are given to their larvae. However, larvae are only fed insects when they have reached a particular size. Workers mostly collect small insects, sap sucking insects along with the honeydew, which is taken to their nests to feed their young.

Blindsnakes of the family Typhlopidae are known to consume Myrmecia broods, although smaller blindsnakes avoid them since they are vulnerable to their stings. Predatory invertebrates such as assassin bugs and redback spiders prey on jack jumpers and other Myrmecia ants. Thorny devils and echidnas, particularly the short beaked echidna (Tachyglossus aculeatus) hunt jack jumper ants, eating their larvae and eggs. Nymphs of the assassin bug species Ptilocnemus lemur lure these ants by trying to make the ant sting them. The jack jumper ant is a host to the parasite gregarines (Gregarinasina). Ants that host this parasite change colour from their typical black appearance to brown. This was discovered when brown jack jumpers were dissected and found to have Gregarinasina spores, while black jack jumpers showed no spores.

Like every ant, the life of a jack jumper ant starts from an egg. If the egg is fertilised, the ant will be a female (diploid); if not, it will become a male (haploid). They develop through complete metamorphosis, meaning that they pass through larval and pupal stages before emerging as an adult. Cocoons that are isolated from the colony are able to shed their pupal skin before hatching, allowing themselves to advance to full pigmentation. Pupae can also eclose (emerge from their pupal stage) without assistance from other ants. Based on observations of six worker ants, the average life expectancy of the jack jumper is around 1.3 years, but workers were shown to live as little as 1.12 years or as long as 1.6, with the queen living much longer than the workers at 10 years or more. Egg clumping is common, as observed in laboratory colonies. George C. Wheeler and Jeanette Wheeler (1971) studied and described larvae collected from New South Wales and South Australia. They noted that very young larvae of the jack jumper were in length, with two types of body hair. They also described young larvae (matured from very young larvae) at , but with similar body characteristics to mature larvae, at .

Queens are polyandrous, meaning that queens can mate more than once; queens mate with one to nine males during a nuptial flight, and the effective number of mates per queen ranges from 1.0 to 11.4. Most queen ants only mate with one or two males. Based on a study, 11 of the 14 colonies tested were polygynous (78.57%), showing that this is common in jack jumper colonies. Nests can hold as few as 500 ants or as many as 800 to 1,000. Excavated nests typically have populations ranging from 34 to 344 individuals. Jack jumper ant workers are gamergates, having the ability to reproduce in colonies with or without queens. Colonies are mainly polygynous with polyandrous queens, but polyandry in jack jumper colonies is low in comparison to other Myrmecia ants, but it is comparable to M. pyriformis ants. In 1979, Craig and Crozier investigated the genetic structure of jack jumper ant colonies, and although queens are unrelated to each other, the occurrence of related queens in a single colony was possible. During colony foundation, suggestions exist of dependent colony foundation in jack jumper queens, although independent colony foundations can occur, as the queens do have fully developed wings and can fly. Some queens could even try to return to their nests that they came from after nuptial flight, but end in another nest, in association that nests nearby will be similar to the queen's birth nest. Jack jumper ants are taxonomically discussed as a single biological species in the Myrmecia pilosula species complex.

The earliest known account of ant sting fatalities in Australia was first recorded in 1931; two adults and an infant girl from New South Wales died from ant stings, possibly from the jack jumper ant or M. pyriformis. Thirty years later, another fatality was reported in 1963 in Tasmania. Historical and IgE results have suggested these two species or perhaps another species were responsible for all recorded deaths. All known patients who died from jack jumper stings were at least 40 years old and had cardiopulmonary comorbidities. Before venom immunotherapy, whole body extract immunotherapy was widely used due to its apparent effectiveness, and it was the only immunotherapy used on ants. However, fatal failures were reported and this led to scientists researching for alternative methods of desensitisation. Whole body extract immunotherapy was later proven to be ineffective, and venom immunotherapy was found to be safe and effective to use. Paul Clarke first drew medical attention to the jack jumper ant in 1986, and before this, there had been no history of records of allergic reactions or study on their sting venom. The identification of venom allergens began in the early 1990s in preparation for therapeutic use. Whole body extracts were first used to desensitize patients, but it was found to be ineffective and later withdrawn. Venom immunotherapy was shown to reduce the risk of systemic reactions, demonstrating that immunotherapy can be provided for ant sting allergies. The ant is a significant cause of major insect allergies, responsible for most anaphylaxis cases in Australia, One in three million annually die of general anaphalaxis in Australia alone. Over 90% of Australian ant venom allergies have been caused by the jack jumper. The ant is notorious in Tasmania, where most fatalities have been recorded. In 2005, over a quarter of all jack jumper sting incidents were sustained in Tasmania; excessive in comparison to its 2006 population of only 476,000 people. Jack jumper stings are the single most common cause of anaphylaxis in patients at the Royal Hobart Hospital. The jack jumper have been compared to other highly aggressive ant species, such as Brachyponera chinensis, Brachyponera sennaarensis, and the red imported fire ant (Solenopsis invicta). The retractable sting is located in their abdomen, attached to a single venom gland connected by the venom sac, which is where the venom is accumulated. Exocrine glands are known in jack jumpers, which produce the venom compounds later used to inject into their victims. Their venom contains haemolytic and eicosanoid elements and histamines. It contains a range of active ingredients and enzymatic activity, which includes phospholipase A2 and B, hyaluronidase, acid and alkaline phosphatase. The venom of the ant also contains several peptides; one being pilosulin 1, which causes cytotoxic effects, pilosulin 2, which has antihypertensive properties and pilosulin 3, which is known to be a major allergen. Other pilosulins include pilosulin 4 and pilosulin 5. The peptides have known molecular weights. The LD50 (lethal dose) occurs at a lower concentration than for melittin, a peptide found in bee venom. Its LD50 value is 3.6 mg/kg (injected intravenously in mice). Loss of cell viability in the jack jumper's venom was researched through cytometry, which measures the proportions of cells that glow in the presence of fluorescent dye and 7 Aminoactinomycin D. Examinations of the rapidly reproducing Epstein–Barr B cells showed that the cells lost viability within minutes when exposed to pilosulin 1. Normal white blood cells were also found to alter easily when exposed to pilosulin 1. However, partial peptides of pilosulin 1 were less efficient at lowering cell viability; the residue 22 N terminal plays a critical role in the cytotoxic activity of pilosulin 1. An East Carolina University study which summarised the knowledge about ant stings and their venom showed that only the fire ant and jack jumper had the allergenic components of their venom extensively investigated. These allergenic components include peptides found as heterodimers, homodimers and pilosulin 3. Due to the vast differentiation of venom produced in each Myrmecia species, and other species sharing similar characteristics to the jack jumper ant, diagnosing which ant is responsible for an anaphylactic reaction is difficult. People most commonly feel a sharp pain after these stings, similar to that from an electric shock. Some patients develop a systemic skin reaction after being stung. Localised envenomation occurs with every sting, but severe envenoming only occurs if someone has been stung many times (as many as 50 to 300 stings in adults). The heart rate increases, and blood pressure falls rapidly. Most people will only experience mild skin irritation after being stung. Those who suffer from a severe allergic reaction will show a wide variety of symptoms. This includes difficulty breathing and talking, the tongue and throat will swell up, and coughing, chest tightness, abdominal pain, nausea and vomiting may occur. Others may lose consciousness and collapse (sometimes people may not collapse), and confusion. Children who get stung will show symptoms such as floppiness and paleness if a severe allergic reaction occurs. In individuals allergic to the venom (about 2–3% of the population), a sting sometimes causes anaphylactic shock. In comparison to other insects such as the western honeybee (Apis mellifera) and the European wasp (Vespula germanica), their rates are only 1.4% and 0.6%. The annual sting exposure rates for the jack jumper ant, Western honeybee and European wasp are 12%, 7% and 2%. About half of these reactions were life threatening and occurred predominantly in people who had had previous incidents with the sting. The sensitivity to stings is persistent for many years. Most people recover uneventfully following a mild local reaction and up to about 3% of individuals suffer a severe localised reaction. Other treatments include washing the stung area with soap and water, and if continuous pain remains for several days, antihistamine tablets are taken for one to three days. Emergency treatment is needed in a case of a severe allergic reaction. Before calling for help, have the person lie down and elevate their legs. Depending on a patient's needs, they will be given an EpiPen or an Anapen to use in case they are stung. In a scenario of experiencing anaphylaxis, further doses of adrenaline and intravenous infusions may be required. Some with severe anaphylaxis may suffer cardiac arrest and will need resuscitation. Another plant used as a bush remedy is Carpobrotus glaucescens (known as angular sea fig or pigface).

Desensitisation (also called allergy immunotherapy) to the jack jumper sting venom has shown effectiveness in preventing anaphylaxis, but the standardisation of jack jumper venom is yet to be validated. Unlike bee and wasp sting immunotherapy, jack jumper immunotherapy lacks funding and no government rebate is available. Venom is available; however, no commercial venom extract is available that can be used for skin testing. Venom extract is only available through the Therapeutic Goods Administration Special Access Scheme. Professor Simon Brown, who founded the program, commented, "Closing the program will leave 300 patients hanging in the lurch". The Royal Adelaide Hospital runs a small scale program that desensitises patients to the ant's venom. Patients are given an injection of venom under the skin in small amounts. During immunotherapy, the first dose is small, but will gradually increase per injection. This sort of immunotherapy is designed to change how the immune system reacts to increased doses of venom entering the body. Both rapid and slow doses can be done safely during immunotherapy. The efficacy (capacity to induce a therapeutic effect) of ant venom immunotherapy is effective in reducing systemic reactions in comparison to placebo and whole body extract immunotherapy, where patients were more likely to suffer from a systemic reaction. Despite immunotherapy being successful, only ten percent of patients do not have any response to desensitisation. It is suggested that people should avoid jack jumpers, but this is difficult to do. Closed footwear (boots and shoes) along with socks reduce the chances of encountering a sting, but wearing thongs or sandals will put the person at risk. With this said, they are still capable of stinging through fabric, and can find their way through gaps in clothing. Most stings occur when people are gardening, so taking extra caution or avoiding gardening altogether is recommended. People can also avoid encountering jack jumpers by moving to locations where jack jumper populations are either low or absent, or eliminate nearby nests. Since Myrmecia ants have different venoms, people who are allergic to them are advised to stay away from all Myrmecia ants, especially to ones they have not encountered before.