Gasterophilus intestinalis

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Gasterophilus intestinalis
Gasterophilusintestinalis.JPG
Adult Gasterophilus intestinalis
Gasterophlusintestinaliseggs.JPG
G. intestinalis eggs on the foreleg of a horse
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Diptera
Family: Oestridae
Genus: Gasterophilus
Species:
G. intestinalis
Binomial name
Gasterophilus intestinalis
de Geer 1776
Synonyms [1]
  • Oestrus intestinalisde Geer 1776
  • Oestrus equiClark 1797

Gasterophilus intestinalis, also known as horse bot fly, is a species of insect of the family Oestridae, [2] and is found worldwide. [3] The adults, which have a bumblebee-like appearance, are prominently active in the summer. [4] G. intestinalis is primarily a parasite of horses, mules and donkeys, [5] rarely of other animals. [6]

Contents

Identification

The eggs of G. intestinalis are pale yellow in color, [7] and 1–2 mm (0.039–0.079 in) long. [4] The larvae are yellow or tan. [3] Adults, which are 10–15 mm (0.39–0.59 in) long, [5] look superficially like hairy bumblebees, with a noticeable ovipositor at the end of the abdomen. [4]

Life cycle

The female fly cements individual eggs onto hairs of the forelimbs and shoulders of horses, mules and donkeys. [7] [5] Each female lays up to 1000 eggs. [7] In order to hatch, the eggs must be licked by the host animal. [5] If taken into the host's mouth during grooming, the egg will hatch in the mouth. [5] If not, the first instar larva will migrate to the mouth. [5] The larvae develop in the tissue of the tongue, [3] in tunnels within 1.5 mm (0.059 in) of the surface. [8] Second instar larvae are swallowed and pass into the host's stomach, [3] and attach to the non-glandular region of the stomach. [9] The larvae remain in the stomach for 8–10 months, [5] before maturing into third instar larvae. [3] In the spring, the third stage larvae pass out of the host in the feces. [3] Pupation takes place in the soil for a duration of 3–5 weeks, until the adults emerge. [5] Adults are active for only a few weeks in the summer, [4] and, lacking functional mouthparts, live only for a short time. [5]

Effects on the host

Clinical signs are uncommon in host animals. [3] Large numbers of larvae in the stomach can cause pain in the stomach, [3] and, rarely, extremely large infestations may cause an obstruction at the outflow from the stomach to the duodenum. [8] The larvae are usually found incidentally when the host's stomach is examined by endoscope. [3] Often the only sign of infestation is the finding of larvae in the feces. [4] The main impact on the host is the nuisance of the adults as they repeatedly land on the legs when attempting to lay eggs. [4]

Treatment and control

Parasiticides which are effective against the larvae include macrolytic lactones, such as ivermectin and moxidectin, and organophosphates, such as metrifonate (also known as trichlorphon) and dichlorvos. [7] The best time to deworm horses against Gasterophilus intestinalis is after the first hard frost. This hard frost will kill the females so no new eggs can be laid on the horse that can be ingested. Meaning that the dewormer is acting on the larva attached to the stomach and will also decrease the amount of larva shed in the feces in the spring. [10]

Prevention

Although deworming is the best treatment and prevention of bot flies, horse owners can take other steps to prevent bot fly egg ingestion. This can be done by manually removing the eggs from the horse's leg using specialized tools, such as bot knives. [10] However, it is important to wash your hands after physically removing the eggs because there is a possibility of the larvae burrowing into the human skin. [11] In addition to removing the eggs manually, there are a few management changes that can be made to decrease the amount of bot flies. Since part of the life-cycle is spent developing in the manure, manure should be removed from horse's pens regularly and composted before place on pasture land. If possible, rotational grazing with different species is beneficial. Lastly, making sure feed and water are free from contamination with manure. [10]

Related Research Articles

<span class="mw-page-title-main">Botfly</span> Parasitic insect

Botflies, also known as warble flies, heel flies, and gadflies, are flies of the family Oestridae. Their larvae are internal parasites of mammals, some species growing in the host's flesh and others within the gut. Dermatobia hominis is the only species of botfly known to parasitize humans routinely, though other species of flies cause myiasis in humans.

<i>Gasterophilus</i> Genus of flies

Gasterophilus, commonly known as botfly, is a genus of parasitic fly from the family Oestridae that affects different types of animals, especially horses, but it can also act on cows, sheep, and goats. A case has also been recorded in a human baby.

<i>Gasterophilus haemorrhoidalis</i> Species of fly

Gasterophilus haemorrhoidalis is a species of the genus Gasterophilus that lays eggs on the lips and around the mouth of horses, mules and donkeys. Their hatching is simulated by moisture from licking or feeding of hosts.

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<span class="mw-page-title-main">Myiasis</span> Infestation of parasitic maggots

Myiasis, also known as flystrike or fly strike, is the parasitic infestation of the body of a live animal by fly larvae (maggots) that grow inside the host while feeding on its tissue. Although flies are most commonly attracted to open wounds and urine- or feces-soaked fur, some species can create an infestation even on unbroken skin. Non-myiatic flies can be responsible for accidental myiasis.

<i>Baylisascaris</i> Genus of worms

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<i>Cobboldia</i> Genus of parasitic flies

Cobboldia is a genus of parasitic flies in the family Oestridae. Adult flies of Cobboldia elephantis lay their eggs near the mouth or base of the tusks of Asian elephant while the related Cobboldia loxodontis parasitizes African elephants. The larvae hatch and develop in the mouth cavity and later move to the stomach. On maturing, the third instar larvae exit from the mouth and drop to the ground to pupate.

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<i>Haematobia irritans</i> Species of fly

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<i>Toxocara canis</i> Species of roundworm

Toxocara canis is a worldwide-distributed helminth parasite that primarily infects dogs and other canids, but can also infect other animals including humans. The name is derived from the Greek word "toxon," meaning bow or quiver, and the Latin word "caro," meaning flesh. T. canis live in the small intestine of the definitive host. This parasite is very common in puppies and somewhat less common in adult dogs. In adult dogs, infection is usually asymptomatic but may be characterized by diarrhea. By contrast, untreated infection with Toxocara canis can be fatal in puppies, causing diarrhea, vomiting, pneumonia, enlarged abdomen, flatulence, poor growth rate, and other complications.

<span class="mw-page-title-main">Microfilaria</span> Early stage in the life cycle of certain parasitic nematodes in the family Onchocercidae

The microfilaria is an early stage in the life cycle of certain parasitic nematodes in the family Onchocercidae. In these species, the adults live in a tissue or the circulatory system of vertebrates. They release microfilariae into the bloodstream of the vertebrate host. The microfilariae are taken up by blood-feeding arthropod vectors. In the intermediate host the microfilariae develop into infective larvae that can be transmitted to a new vertebrate host.

<i>Oestrus ovis</i> Species of fly

Oestrus ovis, the sheep bot fly, is a widespread species of fly of the genus Oestrus. It is known for its parasitic predation and damage to sheep, deer, goats and sometimes cattle. There have also been many records of horse, dog and human infestation. In some areas of the world it is a significant pest which affects the agricultural economy.

<i>Parascaris equorum</i> Species of roundworm

Parascaris equorum is a species of ascarid that is the equine roundworm. Amongst horse owners, the parasites are colloquially called "Ascarids". This is a host-specific helminth intestinal parasite that can infect horses, donkeys, and zebras. Horses up to six months of age are the most susceptible to infection. After this time, infection rates begin to decline and is extremely uncommon in horses over twelve months of age. It cannot infect humans or other animals. It is yellow-white in color, and females can become as large as 15 inches (38 cm) in length. Found worldwide, P. equorum is one of the most difficult equine parasites to kill, requiring larger doses of more powerful anthelmintic medications than are needed for other equine parasites.

Cordylobia rodhaini, also known as the Lund's fly, derived its common name from captain Lund, who was the first European to show symptoms of the disease caused by the larvae of the same fly. Lund’s fly belongs to the genus Cordylobia, flies from the family Calliphoridae. The larvae of the Lund’s fly are parasites of thinned-skinned mammals, especially the Gambian rat, mona monkey and small antelopes and are only accidental parasites of humans. The adult flies feeds on rotting fruits, vegetables and animal feces, and are most abundant in the wet season. Like many tropical insects they are most active in the dark periods and have the greatest activity early in the morning and late in the evening while resting typically between 8am to 5pm. The Lund’s fly are largely confined to tropical Africa, especially the rainforest areas in Sub-Saharan Africa. As a result of human migration, though, the parasitic infections they cause have been recorded in other continents, including Europe and Asia.

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Many species of flies of the two-winged type, Order Diptera, such as mosquitoes, horse-flies, blow-flies and warble-flies, cause direct parasitic disease to domestic animals, and transmit organisms that cause diseases. These infestations and infections cause distress to companion animals, and in livestock industry the financial costs of these diseases are high. These problems occur wherever domestic animals are reared. This article provides an overview of parasitic flies from a veterinary perspective, with emphasis on the disease-causing relationships between these flies and their host animals. The article is organized following the taxonomic hierarchy of these flies in the phylum Arthropoda, order Insecta. Families and genera of dipteran flies are emphasized rather than many individual species. Disease caused by the feeding activity of the flies is described here under parasitic disease. Disease caused by small pathogenic organisms that pass from the flies to domestic animals is described here under transmitted organisms; prominent examples are provided from the many species.

<i>Cuterebra fontinella</i> Species of fly

Cuterebra fontinella, the mouse bot fly, is a species of New World skin bot fly in the family Oestridae. C. fontinella is typically around 1 cm (0.39 in) in length with a black and yellow color pattern. C. fontinella develops by parasitizing nutrients from its host, typically the white-footed mouse. C. fontinella has even been known to parasitize humans in rare cases. Individuals parasitized by C. fontinella will develop a large bump on the skin that is indicative of parasitization.

<i>Gasterophilus nasalis</i> Species of fly

Gasterophilus nasalis is a species of the genus Gasterophilus and family Oestridae. This species is found worldwide, but prominently present within the summer months. This species of G. nasalis primarily targets equines, such as horses, donkeys and the plains zebra. However, it's known that it targets cattle as well, along with mild cases of companion animals.

<i>Physocephala tibialis</i> Species of fly

Physocephala tibialis is a species of thick-headed fly found throughout the eastern United States, often near flowering plants. The adult fly is primarily black with a yellow face and thin white stripes on the abdomen. It is commonly found along the east coast of the United States and is often found near flowering plants.

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References

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