Final Exam: Bot flies and screwworms Flashcards
maggot infestation in animal/human tissue
myiasis
normally in tropics and subtropics
horse bots, cattle grubs, sheep/deer nose bot, primary and secondary screwworms
3 types of myiasis
1) obligatory: essential for life cycle (horse bots, cattle grubs, primary screwworm flies)
2) facultative: usually in decaying organic matter-can develop in necrotic tissue (secondary screwworm flies, flesh flies)
3) accidental: non-specific, ingested (soldier flies, fruit flies)
rodent bots egg laying strategies
lay 1200-1400 eggs around small animal burrows and runways
hatch in response to temp or CO2
enter hose around eyes, nose or wound (under skin for 3-6 days)
cattle grubs/horse bots egg laying strategies
adult female finds host and lays eggs - 400 glues to hairs of hosts
human/tropical bot fly egg laying strategies
glue eggs on “porters” (flies/mosquitoes/ticks that visit mammals) hatch in 5-10 min
protects eggs from host grooming “quiet porters
3 types of horse bots
horse bot (most common)
throat bot fly
nose bot fly
invades horses, mules, and donkeys (humans can be invaded but die in a few days)
Oviposition sites for common horse bot, nose and throat bot
Common: eggs on hair on inside of front legs; hatch with warmth and moisture from tongue; larvae left sac of stomach
nose: eggs on hair of muzzle and lips; hatch spontaneously; larvae on lower portions of stomach and duodenum
throat: eggs on hair of jaw and throat; hatch spontaneously; larvae on lower portions of stomach and duodenum
horse bots life cycle
larvae in manure–> pupate in soil—> adult emerges and lays eggs –> develop in horse
larvae first burrow into tongue, gums, or mouth lining and stay for about 4 wks - molt and move to stomach for about 9 mo
absorb nutrition from horses stomach
all 3 species of horse fly pupate
in the soil
impact of horse bots
consume nutrients, interfere with food passage, cause stomach lesions, secondary infection sites, rundown appearance
horse bot control
dewormers applied after kiling frost tokill larvae in stomach, sponging or slipping to remove eggs, egg scraper
cattle grubs are also known as
warble
oviposition sites for common and northern cattle grubs
common: single eggs on base of hair on legs or lower body regions; hatch spontaneously; larvae in mucosa of esophagus then to back
northern: single eggs on base of hair on legs or lower body regions; hatch spontaneously; larvae in tissue of spinal cord then to back
how cattle grubs live in cattle
warble or cyst on back grows rapidly feeding on pus, necrotic cells and secretions from cyst. 2 mo there. squeezes thru breathing hole - pupates in soil
when and how do mature cattle group larvae leave
leave thru breathing hole and pupate in the soil in the summer
NOT going through digestive tract!
life cycle of cattle grubs
egg april-june
warbles dec-jan
pupation feb-late march
cattle grub impact
injury fleeing from adults; carcass and hide value reduced; improperly timed treatments can kill migrating grubs in esophageal wall (causing drooling or bloat) or stiffness, muscular weakness, or paralysis of hind limbs
gadding
jumping and bucking and trying to get away form buzzing of flies
cattle grub control
dewormers applied depending location of cattle at time of heel fly activity
want to control before they get to a sensitive area (around esophagus and nerves) and before they are too big
sheep nose bot
larvae deposited in nose; in nasal passages and sinuses of sheep and goats; profuse nasal discharge; can impari breathing - nasal infections
larviposition
depositing a LIVE larvae rather than an egg
sheep nose bot larvae exit
must be sneezed out - pupate in soil
deer nose bot
have little spines that helps them with traction
human bot fly
eggs laid on biting fly - mosquito, stable fly
mosquito on host triggers bot egg hatch
larvae burrow into skin
do not migrate
primary screwworm fly (blow flies)
metallic green - maggots infest open wounds and destroy HEALTHY tissue; goes to liquid around wounds to feed
primary screwworm fly host
any warm-blooded mammal
screwworm fly mating
males mate several times, females only once
where to primary screwworm flies pupate
soil
primary screwworm fly oviposition
eggs laid on skin near open wounds
maggots feed in wounds then move to healthy tissue, toxic saliva promotes infection and foul smelling pus
primary screwworm fly impact
infected animals may feed less, may die
sterile male control
males sterilized by gamma radiation, wild females had little chance to mate with wild males –> females lay infertile eggs
secondary screwworm flies (blow flies)
invade wounds or manure buildups but do not attack healthy tissue
surgical maggots
intentional introduction of disinfected maggots into non-healing soft tissue wounds
reared under sterile conditions
removal of necrotic tissue, stimulates blood vessel growth
example of a use of maggots with horses
laminitis
secondary screwworm activity
maggots suppress immune system of host; reduce level of complement proteins involved in inflammatory response; faster wound healing due to increased O2 concentration in wound and enhanced cell growth
