10 Formigas mais perigosas do Mundo (em inglês)1. Fire ants
A fire ant worker, queen, and male (clockwise from bottom left)
Fire ants are a variety of stinging ants with over 285 species worldwide. They have several common names, including ginger ants, tropical fire ants, and red ants.
Fire ants can be distinguished from other ants by their copper brown head and body with a darker abdomen. The worker ants are blackish to reddish, and their size varies from 2 mm to 6 mm (0.12 in to 0.24 in). These different sizes of the ants can all be present in the same nest.
Solenopsis spp. ants can be identified by three body features—a pedicel with two nodes, an unarmed propodeum, and antennae with 10 segments and a two-segmented club.
Many ants bite, and formicine ants can cause irritation by spraying formic acid; myrmecine ants like fire ants have a dedicated venom-injecting sting which injects an alkaloid venom as well as mandibles.
2. Jumping Jack ant or Bull ants
The jack jumper ant, hopper ant, jumper ant or jumping jack, Myrmecia pilosula, is a species of bull ant that is native to Australia. The ants are recorded throughout the country, but are most often found in Tasmania, rural Victoria, New South Wales, Australian Capital Territory and the southeast area of South Australia.
These ants are black or red and black, and may have yellow or orange legs, antennae and mandibles. They are 10-12 mm long. Their characteristic jumping motion when in an agitated state gave them their name. Their nests may be inconspicuously hidden under a rock, or may be formed from a 20 to 60 cm diameter mound of finely granular gravel.
As with many species of bull ants, jack jumper ants are usually solitary when they forage, though they live in colonies like most ants, and only workers forage. They are highly territorial; fights among jack jumper ants from different, and even the same, colonies are not uncommon.
Jack jumper ants are carnivores and scavengers. They sting their victims with venom that is similar to stings of wasps, bees, and fire ants. Their venom is one of the most powerful in the insect world. Jack jumper ants are proven hunters; even wasps are hunted and devoured. These ants have excellent vision, which aids them in hunting.
The symptoms of the stings of the ants are similar to stings of the fire ants. The reaction is local swelling and reddening, and fever, followed by formation of a blister. The heart rate increases, and blood pressure falls rapidly. In individuals allergic to the venom (about 3% of cases), a sting sometimes causes anaphylactic shock. Although 3% may seem small, jack jumper ants cause more deaths in Tasmania than spiders, snakes, wasps, and sharks combined.
Treatment is very similar to wasp and bee stings. There is also an allergy immunotherapy program developed for jack jumper stings using their own venom.
3. Yellow Harvester
The Maricopa harvester ant, Pogonomyrmex maricopa, is one of the most common species of harvester ant species found in Arizona, USA. Its venom is believed to be the most toxic insect venom in the world.
The toxicity of the venom of the Maricopa harvester ant is well known. Its LD50 value is 0.12 mg/kg (injected intravenously in mice); 12 stings can kill a 2-kg rat. In comparison, the LD50 of the honey bee is 2.8 mg/kg — less than 1/20th as strong. Although the toxicity of the venom of the Maricopa harvester ant is the highest tested for any insect, it pales in comparison to that of the most venomous snake (i.e., the Inland Taipan's venom has an LD50 of 0.01 mg/kg in mice) or the most poisonous frog (i.e., the poison dart frog's toxin has a mean LD50 of 0.0002 mg/kg in mice). In humans, a Pogonomyrmex sting produces intense pain that can last up to four hours.
Like many venomous insects, the venom of the Maricopa harvester ant consists of amino acids, peptides, and proteins. This may also encompass alkaloids, terpenes, polysaccharides, biogenic amines, and organic acids. The most notable component found in the venom of the Maricopa harvester ant is an alkaloid poison—this releases an "alarm" pheromone that chemically alerts other ants in the vicinity. This is an example of chemical signaling, which explains why ants all appear to sting at once. The venom can also contain allergenic proteins that are otherwise known to set off a potentially lethal immune response in certain victims.
Similar to the two-part process of the fire ant bite and sting, the harvester ant will attach to the victim with its mandibles, and so proceed by pivoting around the site, allowing the ant to repeatedly sting and inject venom into the region.
The Maricopa harvester ant plays a major role in decomposition by dragging dead carcasses of insects underground, thereby enriching soil for plants and crops.
4. Red Harvester
The red harvester ant (Pogonomyrmex barbatus) is a large (5–7 millimetres) ant common in the southwest United States.
As with most ant species, their mating castes consist of winged alates (reproductives) that reside in the nest until weather permits them to fly away and mate. After that the male usually dies, while the now-fertilized queen returns to the ground to search for a suitable nesting site. Once she has chosen a site, she sheds her wings and begins to reproduce, creating a new colony. She produces "worker ants" for 1–20 years until her death.
Red harvester ants defend their colonies vigorously against real or perceived attacks, whether by large or small animals. They bite ferociously and their stings are venomous and painful. The effect spreads through the lymphatic system, sometimes causing dangerous reactions, especially in animals sensitive or allergic to their venom.
5. Weaver Ants
A weaver ant in fighting position, mandibles wide open
Trap-jaw ants of the genus Odontomachus are equipped with mandibles called trap-jaws, which snap shut faster than any other predatory appendages within the animal kingdom. One study of Odontomachus bauri recorded peak speeds of between 126 and 230 km/h (78 – 143 mph), with the jaws closing within 130 microseconds on average.
The ants were also observed to use their jaws as a catapult to eject intruders or fling themselves backward to escape a threat. Before striking, the ant opens its mandibles extremely widely and locks them in this position by an internal mechanism. Energy is stored in a thick band of muscle and explosively released when triggered by the stimulation of sensory organs resembling hairs on the inside of the mandibles. The mandibles also permit slow and fine movements for other tasks.
These ants are highly territorial and workers aggressively defend their territories against intruders. Because of their aggressive behaviour, weaver ants are sometime used by indigenous farmers, particularly in southeast Asia, as natural biocontrol agents against agricultural pests. Although Oecophylla weaver ants lack a functional sting they can inflict painful bites and often spray formic acid directly at the bite wound resulting in intense discomfort.
6. Bullet ants
Paraponera is a genus of ant consisting of a single species, commonly known as the lesser giant hunting ant, conga ant, or bullet ant (Paraponera clavata), named on account of its powerful and potent sting. It inhabits humid lowland rainforests from Nicaragua and the extreme east of Honduras south to Paraguay. The bullet ant is called "Hormiga Veinticuatro" or "24 (hour) ant" by the locals, referring to the 24 hours of pain that follow being stung. The species epithet clavata means "club shaped".
The pain caused by this insect's sting is purported to be greater than that of any other Hymenopteran, and is ranked as the most painful according to the Schmidt Sting Pain Index, given a "4+" rating, above the tarantula hawk wasp and, according to some victims, equal to being shot, hence the name of the insect. It is described as causing "waves of burning, throbbing, all-consuming pain that continues unabated for up to 24 hours". It is thought that the ant has evolved this way to ward off any predators who would normally unearth them. A paralyzing neurotoxic peptide isolated from the venom is poneratoxin. It affects voltage-dependent sodium ion channels and blocks the synaptic transmission in the central nervous system. It is being investigated for possible medical applications.
7. Wood Ants
Formica is a genus of ants of the family Formicidae, commonly known as wood ants, mound ants, thatching ants, or field ants. Formica is the type genus of the Formicidae, and of the subfamily Formicinae. In turn Formica's own type species is the European red wood ant Formica rufa.
Wood ants typically secrete formic acid; F. rufa can squirt the acid from its acidopore several feet if alarmed, a habit which may have given rise to the archaic term for ant pismire, and by analogy its American equivalent piss-ant. They can be relatively large: F. rufa workers can reach a maximum length of around 10 mm.
8. Carpenter Ants
Carpenter ants are large (.25 to 1 in/0.64 to 2.5 cm) ants indigenous to many parts of the world. They prefer dead, damp wood in which to build nests. They do not consume it, however, unlike termites. Sometimes carpenter ants will hollow out sections of trees. The most likely species to be infesting a house in the United States is the black carpenter ant (Camponotus pennsylvanicus). However, there are over a thousand other species in the genus Camponotus.
In at least nine Southeast Asian species of the Cylindricus complex, including Camponotus saundersi, workers feature greatly enlarged mandibular glands that run the entire length of the ant's body. They can release their contents suicidally by performing autothysis, thereby rupturing the ant's body and spraying toxic substance from the head, which gives these species the common name "exploding ants.
9. Termite Ants
Termites are a group of eusocial insects that, until recently, were classified at the taxonomic rank of order Isoptera (see taxonomy below), but are now accepted as the epifamily Termitoidae, of the cockroach order Blattodea. While termites are commonly known, especially in Australia, as "white ants", they are only distantly related to the ants.
Like ants, and some bees and wasps—which are all placed in the separate order Hymenoptera—termites divide labor among castes, produce overlapping generations and take care of young collectively. Termites mostly feed on dead plant material, generally in the form of wood, leaf litter, soil, or animal dung, and about 10% of the estimated 4,000 species (about 2,600 taxonomically known) are economically significant as pests that can cause serious structural damage to buildings, crops or plantation forests. Termites are major detritivores, particularly in the subtropical and tropical regions, and their recycling of wood and other plant matter is of considerable ecological importance.
10. Leafcutter Ants
Leafcutter ants, a non-generic name, are any of 47 species of leaf-chewing ants belonging to the two genera Atta cephalotes and Acromyrmex. These species of tropical, fungus-growing ants are all endemic to South and Central America, Mexico and parts of the southern United States. Leafcutter ants "cut and process fresh vegetation (leaves, flowers, and grasses) to serve as the nutritional substrate for their fungal cultivars."
The Acromyrmex and Atta ants have much in common anatomically; however, the two can be identified by their external differences. Atta ants have three pairs of spines and a smooth exoskeleton on the upper surface of the thorax, while Acromyrmex ants have four pairs and a rough exoskeleton.
Next to humans, leafcutter ants form the largest and most complex animal societies on Earth. In a few years, the central mound of their underground nests can grow to more than 30 metres (98 ft) across, with smaller, radiating mounds extending out to a radius of 80 metres (260 ft), taking up 30 to 600 square metres (320 to 6,500 sq ft) and containing eight million individuals.
Majors, the largest worker ants, act as soldiers, defending the nest from intruders, although recent evidence indicates majors participate in other activities, such as clearing the main foraging trails of large debris and carrying bulky items back to the nest. The largest soldiers (Atta laevigata) may have total body lengths up to 16 mm and head widths of 7 mm.
In some parts of their range, leafcutter ants can be quite a nuisance to humans, defoliating crops and damaging roads and farmland with their nest-making activities. For example, some Atta species are capable of defoliating an entire citrus tree in less than 24 hours.