''Gasterophilus'', commonly known as

botfly Botflies, also known as warble flies, heel flies, and gadflies, are a family of flies known as the Oestridae. Their larvae are internal parasites of mammals, some species growing in the host's flesh and others within the gut. ''Dermatobia homin ...

, is a genus of parasitic fly from the family

Oestridae Botflies, also known as warble flies, heel flies, and gadflies, are a family of flies known as the Oestridae. Their larvae are internal parasites of mammals, some species growing in the host's flesh and others within the gut. ''Dermatobia homin ...

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. This parasite affects the animal gastrointestinal tract in order to give to their offspring an alimentary source. Although not deadly, due to the usual low

larva 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 ...

population that infests the animal, large larva populations can cause health issues to the

host A host is a person responsible for guests at an event or for providing hospitality during it. Host may also refer to: Places * Host, Pennsylvania, a village in Berks County People *Jim Host (born 1937), American businessman * Michel Host ...

. For example, a typical horse can tolerate a hundred larvae without any effects.

Species

There are nine species of Gasterophilus: *'' Gasterophilus flavipes'' – ranges

Palaearctic The Palearctic or Palaearctic is the largest of the eight biogeographic realms of the Earth. It stretches across all of Eurasia north of the foothills of the Himalayas, and North Africa. The realm consists of several bioregions: the Euro-Sibe ...

and

Afrotropical The Afrotropical realm is one of Earth's eight biogeographic realms. It includes Africa south of the Sahara Desert, the majority of the Arabian Peninsula, the island of Madagascar, southern Iran and extreme southwestern Pakistan, and the island ...

, primarily infects donkeys *''

Gasterophilus haemorrhoidalis ''Gasterophilus haemorrhoidalis'' (also called nose botfly or lip botfly) is a species of the genus ''Gasterophilus'' that lays eggs on the lips and around the mouth of horses, mules and donkeys. In Equidae, third-stage larvae attach to the sto ...

'' (lip botfly) – ranges worldwide and primarily infects horses, mules, donkey and reindeer *'' Gasterophilus inermis'' – an

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 that infects horses, donkeys and zebra *''

Gasterophilus intestinalis ''Gasterophilus intestinalis'', also known as horse bot fly, is a species of insect of the family Oestridae, and is found worldwide. The adults, which have a bumblebee-like appearance, are prominently active in the summer. ''G. intestinalis'' is ...

'' (horse botfly) – ranges worldwide and primarily infects horses, mules and donkeys *'' Gasterophilus meridionalis'' – ranges Afrotropical and primarily infects zebra *'' Gasterophilus nasalis'' (throat botfly) – especially

Holarctic The Holarctic realm is a biogeographic realm that comprises the majority of habitats found throughout the continents in the Northern Hemisphere. It corresponds to the floristic Boreal Kingdom. It includes both the Nearctic zoogeographical region ...

but ranges worldwide, primarily infects sheep, goats, horses, donkeys, zebra and sometimes cattle *''

Gasterophilus nigricornis ''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 ...

'' (broad-bellied horse bot) – ranges from the

Middle East The Middle East ( ar, الشرق الأوسط, ISO 233: ) is a geopolitical region commonly encompassing Arabian Peninsula, Arabia (including the Arabian Peninsula and Bahrain), Anatolia, Asia Minor (Asian part of Turkey except Hatay Pro ...

China China, officially the People's Republic of China (PRC), is a country in East Asia. It is the world's most populous country, with a population exceeding 1.4 billion, slightly ahead of India. China spans the equivalent of five time zones and ...

, infects

duodenum The duodenum is the first section of the small intestine in most higher vertebrates, including mammals, reptiles, and birds. In fish, the divisions of the small intestine are not as clear, and the terms anterior intestine or proximal intestine m ...

of horses and donkeys *'' Gasterophilus pecorum'' (dark-winged horse bot) – the most

pathogenic In biology, a pathogen ( el, πάθος, "suffering", "passion" and , "producer of") in the oldest and broadest sense, is any organism or agent that can produce disease. A pathogen may also be referred to as an infectious agent, or simply a germ ...

species in the genus. Ranges through the Old World and infects the mouth, tongue,

esophagus The esophagus (American English) or oesophagus (British English; both ), non-technically known also as the food pipe or gullet, is an organ in vertebrates through which food passes, aided by peristaltic contractions, from the pharynx to the ...

and stomach of horses, donkeys and zebras *'' Gasterophilus ternicinctus'' – ranges Afrotropical and primarily infects zebra

Taxonomy

Larva

In the third larval stage, the larvae have a length that can go from 1.27cm to 1.91 cm. They have a hooked mouthpart that allows them to attach into the gastrointestinal tract of the infected animal and a rounded body that is covered with spines in rows, of which quantity varies from different species. After this stage, the larva is excreted with the animal feces in the form of a

pupa A pupa ( la, pupa, "doll"; plural: ''pupae'') is the life stage of some insects undergoing transformation between immature and mature stages. Insects that go through a pupal stage are holometabolous: they go through four distinct stages in their ...

Adult

The adults have a length that can be between 1.67 and 1.91 cm. During this phase they look similar to drone bumble bees; They have developed a pair of wings with brown patches and a body that is covered with yellow and black hairs. Looking into the different species, G. haemorrhoidalis and G. nasalis can be identified because they have two rows of spikes on the ventral surface of the larval segments. G. intestinalis, on the other hand, has mouthparts that are not uniformly curved dorsally and the body spikes present have blunt-ended tips.

Life cycle

The first stage: During the summer months, the full-grown Gasterophilus lays the eggs over the hair, face, and extremities of their future host (these eggs are laid on different portions of the body according to the various Gasterophilus species). Due to the animal grooming that starts after seven days from the egg being laid, the hatched larvae end up in the host mouth and tongue where they get attached for more than a month before being ingested. During this process, the animal can suffer from inflammation of the

oral mucosa The oral mucosa is the mucous membrane lining the inside of the mouth. It comprises stratified squamous epithelium, termed "oral epithelium", and an underlying connective tissue termed ''lamina propria''. The oral cavity has sometimes been descri ...

. The second stage: In this stage, the larvae have been ingested and are now in the gastrointestinal tract of the host where they attach themselves. Here, they mature and stay there from eight to nine months to pass the winter and are released in the spring. During this phase, the infection can manifest in the host's digestive system resulting in

gastritis Gastritis is inflammation of the lining of the stomach. It may occur as a short episode or may be of a long duration. There may be no symptoms but, when symptoms are present, the most common is upper abdominal pain (see dyspepsia). Other possi ...

ulceration An ulcer is a discontinuity or break in a bodily membrane that impedes normal function of the affected organ. According to Robbins's pathology, "ulcer is the breach of the continuity of skin, epithelium or mucous membrane caused by sloughing o ...

, which may result in perforations in the walls of the tract in severe cases and much more. The third stage: The larvae are mature enough to develop their pupa, and once finished they are released with the animal feces during spring. After leaving, which occurs in about 3-10 weeks,(depending on the temperature) the adult bot fly emerges from the pupa and starts the cycle again.

Treatment

The most efficient way known to avoid the infection of Gasterophilus is by parasitizing the animals with products like trichlorphon and dichlorvos, by using hot water to scrub the areas where the eggs are laid to kill the larvae, and by cleaning the areas where the feces of the infected animal had been in order to avoid the adult formation.

Gallery

File:Gasterophilusintestinaliseggs2.JPG, ''G. intestinalis'' eggs on a horse File:Gasterophlusintestinaliseggs.JPG, ''G. intestinalis'' eggs on a horse (closer) File:Magendassel.jpg, ''G. intestinalis'' larva File:Gasterophilus intestinalisOestre.jpg, Drawing of ''G. intestinalis'' larvae in a horse's stomach File:Gasterophilusintestinalis.JPG, ''G. intestinalis'' adult female

References

* https://livestockvetento.tamu.edu/insectspests/bot-flies/

External links

University of São Paulo page
{{Taxonbar, from=Q13553844 Oestridae Parasitic flies Parasites of equines Veterinary entomology Taxa named by William Elford Leach Oestroidea genera