Difference between revisions of "Gasterophilus spp."

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{{OpenPagesTop}}
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[[Image:Horse Bot Fly.jpg|thumb|right|150px|Horse Bot Fly - Dennis Ray - Wikimedia Commons]]
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{{Taxobox
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*Also known as the horse bot fly
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|name              =''Gasterophilus spp.
 
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|kingdom            = Animalia
 
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|phylum            = [[:Category:Arthropods|Arthropoda]]
 
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|class              =[[:Category:Insecta|Insecta]]
 
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|sub-class          = Diptera
 
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|order              =
 
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|super-family      =
 
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|family            =[[Oestridae]]
 
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|sub-family        =
 
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|genus              = Gasterophilus
 
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|species            =
 
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}}
 
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[[Image:Horse Bot Fly.jpg|thumb|right|150px|''Horse Bot Fly'' <br> Dennis Ray 2005, Wikimedia Commons]]
 
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Also known as: '''''Bot Fly — Bots'''
 
  
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==Introduction==
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===Introduction===
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The species ''Gasterophilus'' is of the family [[Oestridae]], and is more commonly referred to as the 'Bot fly.'  It is an obligate parasite found on horses, donkeys, mules, zebras and elephants.   
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The species Gasterophilus, is more commonly referred to as the 'Bot fly.'  It is an obligate parasite found on horses, donkeys, mules, zebras and elephants.   
  
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Infection is particularly common in horses, with around 30-60% infected during the winter months.
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Infection is particularly common in horses, with around 30-60% infected during the winter months.
  
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Within the United Kingdom there are three species of veterinary importance;
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'''Scientific Classification'''
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''G. intestinalis'' which is the most common, and ''G. nasalis'', and ''G. haemorrhoidalis'' which are rare.
 
  
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''G. nigricornis'' and ''G. inermis'' are also of veterinary significance, but not currently within the UK.
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{| cellpadding="10" cellspacing="0" border="1" 
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| Kingdom
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| Animalia
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|-
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| Phylum
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| Arthropoda
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|-
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| Class
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| Insecta
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|-
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| Order
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| Diptera
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|-
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| Family
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| Oestridae
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|-
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| Genus
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| Gasterophilus
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|-
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|}
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===Life Cycle===
  
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[[Image:Gasterophilus larvae.jpg|150px|thumb|right|''Gasterophilus larvae'' <br> Lamiot 2007, Wikimedia Commons]]
 
  
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==Identification==
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*Obligate parasites of equids
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Gasterophilus are medium to large flies at 10-20mm long, and are thought to look similar to drone bumble bees.
 
  
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They have clear wings with brown patches, and produce creamy-white eggs, around 1-2mm in length
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*Spend most of life cycle in the equine stomach
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**Of little pathogenic significance
  
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Adults have non-functional mouthparts so cannot feed.
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*Three important species (in the UK)
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**''G. intestinalis'' which is the most common
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**''G. nasalis''
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**''G. haemorrhoidalis'' which is rare
  
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Both ''G. haemorrhoidalis'' and ''G. nasalis'' have spikes on the ventral surface of the larval segments arranged in two rows. ''G. intestinalis'' have mouth parts that are not uniformly curved dorsally and the body spikes present have blunt ended tips.
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*Two other important veterinary species
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**''G. nigricornis''
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**''G. inermis''
  
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==Life Cycle==
 
  
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Eggs are laid on the body of the host and either hatch spontaneously or are stimulated to hatch through an increase in warmth and moisture from the animal self-grooming. They are laid in different areas according to species;
 
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''G. intestinalis'' eggs are laid in the hair of the shoulders and forelegs. ''G. nasalis'' eggs are laid in the intermandibular area. ''G. haemorrhoidalis'' eggs are laid around the lips
 
  
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L1 are extremely small and motile, and begin development in the mouth, tongue and gums of the host.  The development of L1 into L2 occurs on the pharynx.  L2 then attaches to the base of the tongue and slowly migrates to the stomach.
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===Identification===
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*Medium to large flies at 10-20mm long
  
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L3 attaches to the squamous gastric mucosa along the margo plicatus, in the case of ''G. intestinalis''. ''G. nasalis'' attaches to the dorsoproximal part of the duodenum, and ''G. haemorrhoidalis'' attaches to the gastric epithelium within the stomach.
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*Look similar to drone bumble bees
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**Body covered with dense yellow hair
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**Dark coloured hairs produce a banding pattern
  
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The larvae then remain and develop within the stomach for around 10-12 months.  They mature in the following spring or early summer (generally between May and September), detach from their surface and are passed out in the host faeces. ''G. haemorrhoidalis'' also attaches to the rectal mucosa before being passed out.
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*Clear wings with brown patches
  
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[[Image:Gasterophilus.jpg|200px|thumb|right|''Gasterophilus'' <br> Notafly 2008, Wikimedia Commons]]
 
  
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The larvae then penetrate the soil, where they transform into pupae and the flies hatch 30 to 40 days later.
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'''Life cycle'''
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*Adults are most active in '''late summer'''
  
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They are only found on pasture, as they do not survive well on stable bedding.  The pupae are known to be sensitive to frost, moisture and flooding, so the environmental conditions present play a significant role in the success of the parasite.
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*Eggs are laid on the body and hatch spontaneously or are stimulated to hatch through an increase in warmth and moisture from the animal self-grooming. They are laid in different areas according to species
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**''G. intestinalis'' eggs are laid in the hair of the shoulders and fore legs
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**''G. nasalis'' eggs are laid in the intermandibular area
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**''G. haemorrhoidalis'' eggs are laid around the lips
  
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{{Learning
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*Creamy-white eggs
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|flashcards = [[Myiasis_Producing_Flies_Flashcards|Myiasis Producing Flies Flashcards]]
 
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|literature search =[http://www.cabdirect.org/search.html?q=title%3A%28%22Gasterophilus%22%29+ ''Gasterophilus'' spp. publications]
 
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|Vetstream = [https://www.vetstream.com/canis/Content/Disease/dis60301.asp Myiasis]
 
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}}
 
  
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*1-2mm in length
  
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{{review}}
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*Larvae crawl into the mouth and penetrate the tissues of the tongue and buccal mucosa
  
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{{OpenPages}}
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*Larvae then emerge after a couple of weeks and are swallowed
  
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[[Category:Oestridae]]
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*Larvae pass into the [[Forestomach - Anatomy & Physiology|stomach]] and attach to the gastric mucosa
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**Larvae are now known as '''bots'''
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*Each species attaches to a specific part of the stomach
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**''G. intestinalis'' attaches to the cardiac region
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**''G. nasalis'' attaches to the pylorus
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*After 10-12 months in the stomach, the larvae detach and are passed out in the faeces
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**''G. haemorrhoidalis'' attaches to the rectal mucosa before being passed out
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*Larvae pupate on the ground
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*Adults hatch after 1-2 months and survive from a few days to 2 weeks
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**Adults have non-functional mouthparts so cannot feed
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*There is only '''1 generation per year''' in temperate regions of the world
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'''Pathogenesis'''
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*Adults cause annoyance when egg laying
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**Disturbance and panic can ensue
 +
 
 +
*Larvae cause a marked inflammatory reaction when attached to the gastric mucosa
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**Ring like thickening around the base of each attached larvae
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*Large numbers of larvae may interfere with the passage of food and action of gastric sphincters
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*''G. haemorrhoidalis'' can cause mild irritation to the rectal wall
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*Host reaction to larvae in the mouth is minimal
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'''Control'''
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*Treatment of horses with [[Ectoparasiticides|insecticides]] over winter
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**Breaks the life cycle as all the population are present as bots in the [[Forestomach - Anatomy & Physiology|stomach]]
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*If eggs are present in late summer, the horse's coat can be sponged with an [[Ectoparasiticides|insecticide]]
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**Stimulates hatching
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**Kills larvae
  
  
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[[Category:Expert_Review]]
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[[Category:Oestridae]]
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[[Category:Horse Parasites]]
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[[Category:To_Do_-_Max]]

Revision as of 09:21, 9 July 2010

Horse Bot Fly - Dennis Ray - Wikimedia Commons
  • Also known as the horse bot fly

Introduction

The species Gasterophilus, is more commonly referred to as the 'Bot fly.' It is an obligate parasite found on horses, donkeys, mules, zebras and elephants.

Infection is particularly common in horses, with around 30-60% infected during the winter months.

Scientific Classification

Kingdom Animalia
Phylum Arthropoda
Class Insecta
Order Diptera
Family Oestridae
Genus Gasterophilus

Life Cycle

  • Obligate parasites of equids
  • Spend most of life cycle in the equine stomach
    • Of little pathogenic significance
  • Three important species (in the UK)
    • G. intestinalis which is the most common
    • G. nasalis
    • G. haemorrhoidalis which is rare
  • Two other important veterinary species
    • G. nigricornis
    • G. inermis


Identification

  • Medium to large flies at 10-20mm long
  • Look similar to drone bumble bees
    • Body covered with dense yellow hair
    • Dark coloured hairs produce a banding pattern
  • Clear wings with brown patches


Life cycle

  • Adults are most active in late summer
  • Eggs are laid on the body and hatch spontaneously or are stimulated to hatch through an increase in warmth and moisture from the animal self-grooming. They are laid in different areas according to species
    • G. intestinalis eggs are laid in the hair of the shoulders and fore legs
    • G. nasalis eggs are laid in the intermandibular area
    • G. haemorrhoidalis eggs are laid around the lips
  • Creamy-white eggs
  • 1-2mm in length
  • Larvae crawl into the mouth and penetrate the tissues of the tongue and buccal mucosa
  • Larvae then emerge after a couple of weeks and are swallowed
  • Larvae pass into the stomach and attach to the gastric mucosa
    • Larvae are now known as bots
  • Each species attaches to a specific part of the stomach
    • G. intestinalis attaches to the cardiac region
    • G. nasalis attaches to the pylorus
  • After 10-12 months in the stomach, the larvae detach and are passed out in the faeces
    • G. haemorrhoidalis attaches to the rectal mucosa before being passed out
  • Larvae pupate on the ground
  • Adults hatch after 1-2 months and survive from a few days to 2 weeks
    • Adults have non-functional mouthparts so cannot feed
  • There is only 1 generation per year in temperate regions of the world


Pathogenesis

  • Adults cause annoyance when egg laying
    • Disturbance and panic can ensue
  • Larvae cause a marked inflammatory reaction when attached to the gastric mucosa
    • Ring like thickening around the base of each attached larvae
  • Large numbers of larvae may interfere with the passage of food and action of gastric sphincters
  • G. haemorrhoidalis can cause mild irritation to the rectal wall
  • Host reaction to larvae in the mouth is minimal


Control

  • Treatment of horses with insecticides over winter
    • Breaks the life cycle as all the population are present as bots in the stomach
  • If eggs are present in late summer, the horse's coat can be sponged with an insecticide
    • Stimulates hatching
    • Kills larvae
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