ENI - Flies Flashcards
What are the 2 suborders of diptera?
- Brachycera (short antennae)
- Nematocera (long antennae)
What are the direct effects of flies?
- Bites and allergies
- Botflies
- Myiasis causing flies (fly strike)
What are the indirect effects of flies?
Transmission of infections
Name the 4 families of nematocera
- Simulidae
- Culicidae
- Ceratopogonidae
- Psychodidae
Describe the typical life cycle of Nematocera
- Holometabolomes
- Aquatic life cycle
- Eggs laid (near water)
- 4 larval stages (point into water)
- Pupate
- Hatch
- Mating
- Female requires blood meal for egg production
Name the families of Brachycera
- Muscidae
- tabanidae
- Hippoboscidae
- Glossinidae
- Oestridae
- Sarcophagidae
- Calliphoridae
What is the difference between the life cycles of Nematocera and Brachycera?
Brachycera not usually aquatic life cyces, Nematocera require water
Name common species of Muscidae
- House flies: Musca domestica, M. autumnalis
- Head flies: Hydrotaea irritans
- Stable fly: Stomoxys calcitrans
- Horn flies: Haematobia irritans
Which of the Muscidae are blood feeders?
- Stable fly (Stomoxys calcitrans)
- Horn flies (Haematobia irritans)
Describe Hydrotaea irritans
- Sheep head fly
- Feed on secretions from eyes, nose and debris at horn base
- Feeding causes irritation, scratching resultin in wounds
Describe Haematoba irritans
- Horn flies
- Take blood meal
- most often from cattle
- Painful bites
- Economically importnat
Describe the role of Muscidae as vectors of infection
- Spread bacteria into eyes and wounds
- Pinkeye (Moraxella bovis infection)
- Summer mastitis (though to be by head fly)
- Can also transmit faecal pathogens e.g. Salmonella and Campylobacter among chickens and people
Describe the Tabanidae family
- Brachycera
- Horseflies (Tabanus)
- Deer flies (Haematopota)
- Clegs (Chrysops spp)
- large biting flies
- Diurnal, strong fliers
- Prevent feeding, highly irritant, mechanical vector
What is the most common tabanid in the UK?
Haematopota pluvalis
Describe the feeding of tabanids
- Females bite and drink blood
- Large saw-like mouth parts
Describe the life cycle of tabanids
- Eggs laid on stems of plants
- Larvae live in wet mud or may be completely aquatic
- Require several months to complete life cycle
Descibe the Tsetse fly
- Genus Glossina
- Sub-saharan Africa
- Viviparous
- Vectors of parasitic protozoa
Describe the reproduction of the Tsetse fly
- Viviparous
- Eggs inside female, hatch within then emerge
- Are not deposited until ready to pupate
- Holometabolous life cycle
Describe the life cycle of trypanosomes with relation to the Tsetse fly
- Fly takes blood meal, ingests protozoan
- Protozoan replicates by binary fission in mid-gut of fly
- Transforms into infective stage
- Enters salivary glands and multiplies
- Fly takes blood meal and injects into the bloodstream
- Multiplies by binary fission in blood, lymph and spinal fluid
Describe Simuliidae
- Nematocera
- 1-5mm
- Humped thorax
- Diurnal
- Bite in grey, warm weather
- Transmit infectious diseases
- Aka black flies
- Simulium is most important genus
- Eggs and larvae oxygenated, fast flowing water
- Irritant and pest
Describe the feeding habits of adult Simuliidae
- Adult males: nectar
- Adult females: blood from wide range of vertebrates
Describe mosquitoes
- Culicidae, Nematocera
- 2-10mm
- Slender, long legs, adult females have long proboscis
- Crepuscular/nocturnal
- Poor fliers
- Transmit infectious diseases
- 2 main groups
Give examples of diseases transmitted by mosquitoes
- Plasmodium (malaria)
- Dirofilaria immitis
- Various viruses (e.g. West Nile virus, Myxomatosis, avian poxvirus, equine encephalitis virus, equine infectious anaemia virus)
Outline methods of transmission of diseases by mosquitoes
- Can act as intermediate host/definitive host or mechanical vector
- Vertical transmission between mosquitoes also possible
What are the 2 main groups of mosquito?
- Anopheline (e.g. Aedes spp.)
- Culicine (e.g. Culex spp.)
Describe mosquito breeding
- Aquatic areas
- Eggs laid on water or moist ground
- Larval stages live in still ponds, water butts etc
- Culicine larvae hang down
- Anopheline lay parallel with surface water
Describe feeding in mosquitoes
- Adults drink nectar
- Female has to have blood meal before laying eggs
Describe transmission of Dirofilaria immitis by mosquitos
- Mosquito takes blood meal, ingests microfilaria
- Penetrate mosquito’s midgut, migrate to malphigian tubules
- Moult L1-L3
- Migrate to head and proboscis
- Takes blood meal, L3 into bite wound, infect host
Describe Ceratopogonidae
- Nematocera
- Biting midges
- 1-4mm
- Humped thoax, wings flat at rest
- Crepuscular, dull humid weather
- Poor fliers
- Transmit infectious dieases
- Aquatic/semi-aquatic diseases
- Can be severe irritants and cause allergies
Give an example of an allergy caused by Culicoides
Sweet itch in horses
List diseases transmitted by ceratopogonidae
- Onchocerca spp
- Protozoa
- Viruses e.g. bluetongue, Schmallenberg
- African horse sickness
- Trypanosomes, filaroid nematodes
Describe Psychodidae
- Nematocera
- Sand flies
- 3-5mm
- Hairy, moth-like, long legs, hop not fly
- Nocturnal
- Weak fliers
- Transmit infectious dieases
- Only adult female drinks blood
What diseases are transmitted by Sand flies?
- Leishmania
- Phlebotomus in Eurpor
- Lutzomyia in America
Describe the locations of the egg and larval stages of Sand flies
- Eggs laid on ground
- Larvae (multiple stages) live in humid soil, leaf litter etc
Describe Melophagus ovis
- Sheep ked
- Permanent obligate ectoparasite, no wings
- 5-8mm
- Single egg hatches inside female, 3 moults, then emerges and sticks to hair and pupates
- Transmission through direct contact
What pathology does Melophagus ovis cause?
- Irritation
- Rubbing
- Wool loss
Describe Hippoboscis equina
- New forest fly ~10mm, wings, fly short distances
- Female produces larvae that pupate on ground
- Found on horses and cattle
What are Hypoderma more commonly known as?
- Heel flies
- Warble flies
- Cattle grubs
What are the main species of Hypoderma?
- Hypoderma bovis
- Hypoderma lineatum
Describe the life cycle of Hypoderma
- Adults fly in spring and early summer, lay eggs on skin
- Eggs hatch, larvae migrate and moult through body
- Between muscles to oesophagus or up to nerves to vertebrae then to skin where moult again
- Cut breathing holes to hide in
- Final stage grubs drop to ground and pupate
- Cycle ~1 year
What are the 3 main species of Gasterophilus? What are the differences?
- Intestinalis: lays eggs around knees
- Nasalis: lays eggs under jaw
- Haemorrhoidalis: lays eggs around lips
Describe the life cycle of Gasterophilus species
- Eggs laid in varying places depending on species
- Taken into mouth of horse
- Larvae hatch and migrate through mouth to pharynx then swallowed
- Bind to glandular-non-glandular junction of stomach
- Passed in faeces after moulting
- Pupate in soil into adults
What are Gasterophilus more commonly known as?
Horse bots
What are Oestrus ovis mor commonly known as?
Sheep nasal bot fly
What type of reproduction do Oestrus ovis carry out?
Larviparous
What are the effects of Oestrus ovis infestation?
- Profuse discharge, thickening of nasal mucosa
- Impairs respiration
- Larvae present in sinuses sometimes able to escape, die = septic sinuses
- Sometimes enter brain
What is Lucilia sericata more commonly known as?
Common green bottle
Describe parasitism by Lucilia sericata
- Facultative parasites
- Eat carrion as well as causing strike
- Mainly eat lymph and necrotic tissue
- Only eat healthy tissue when overcrowded
Where are eggs of Lucilia sericata laid?
- Moist areas where infection is already underway
- e.g. deep in fleece or in infected wound
List species of blow flies that cause cause strike in the UK
- Lucilia sericata (common green bottle)
- Phormia regina (black blow fly)
- Calliphora vicina/ erythrocephala ( blue bottle fly)
- Protophormia terraenovae
Describe Sarcophagidae
- Genus Wohlfahrtia
- Flesh flies
- OBligate larval parasite of warm blooded vertebrates in Med, eastern and central Europe, Asia minor
- Cause rapid and severe myiasis i most livestock
What are the potential agents of fly strike/
- Screwworm
- Blow/bottle flies
Describe fly strike lesions in sheep
- Range from cm diameter of skin hyperaemia with small number of maggots
- To extensive areas of traumatised/devitalised skin causing death in neglected cases
What are the legal requirements regarding fly strike in sheep?
- Check low ground and upland sheep daily
- Death of sheep due to blowfly strike can lead to prosecution under animal welfare legislation
Give risk factors for fly strike in sheep
- Faecal staining around perineum
- Virulent foot rot lesions
- Dermatophilosis lesions on skin
- Urine scaling around prepuce
- Leaving shot pests in fields with sheep
Outline control of fly strike in rabbits
- Check rabbit daily, especially in warm months
- Clean immediately if necessary
- Clean litter trays and remove soiled bedding daily
- Staple net curtains over hutch/run
- Look out for conditions prevent self-cleaning e.g dental, spinal, obesity
- Incorrect diets leading to too many caecotrophs
What are the key aspects of fly control?
- Husbandry
- Mechanical
- Chemicals
- Biological control
Describe husbandry in fly control
- Remove litter/manure, carcasses
- Ensure animals are healthy i.e. shear soild wool/fur, clean and protect wounds
Describe mechanical aspects of fly control
- Barriers, meshes, traps
- Cleaning/burning
Describe chemical aspects of fly control
- Insecticides, repellents
- On animal
- On environment
- Fairly non-specific, may kill off other insects
Give examples of biological aspects of fly control
- Parasitoids wasps
- Nematodes/bacteria
Which fly has the least potential to act as a vector of infection and why?
- Bot fly
- Does not take a blood meal
Describe the mouthparts of nematocera
Piercing
What fly acts as a vector for Dirofilaria immitis?
Mosquito
What flies act as vectors for Typanosomiasis?
- Tsetse fly (Glossina)
- Culicoides
What kind of hypersensitivity is Culicoides sensitivity and what is teh condition called?
- Type I, IgE mediateed
- Sweet itch
How is Culicoides sensitivity diagnosed?
- Mainly by ruling out other causes
- Serology for IgE
- Intradermal allergy testing
- history and clinical presentation
Outline teh control of Culicoides hypersensitivity
- Keep in field out of breeze
- Keep in at peak times (msot active at night)
- Use fly rugs
- Control pruritus and treat any secondary infections
- Fly repellent (citronella, DEET)
- Corticosteroids
- Antihistamines
