8. infections caused by fungi Flashcards
chalk brood pathogen
ascosphaerosis larvarum - ascosphaea apis
when was chalk brood discovered
1911 - present in worldwide colonies
pathogenesis of mature ascoma - chalk brood
- Dark brown
- transparent ascoma walls
- small spherical shaped asci
- when ascoma’s rupture spores released
predisposing factors of chalk brood
- high humidity
- decreased temp
- early summer
- small colonies more impacted
how long are chalk brood spores infective for
spores infective for 10-15 years
what bees suffer from chalk brood
drone larvae
how are spores of chalk brood spread
beekeeper activity
age of larvae affected by chalk brood
only 3-4 day old larvae affected
how can a bee get infected per os
through host gut lining
hyphae penetrate gut wall
mycelium break out
larvae die
symptoms of chalk brood
- head of larvae will be unaffected
- no smell of dead larvae
- young larvae show no signs
colour of dead larvae infected with chalk brood
- mummified
- chalky white
- dark blue grey/black
mummies of chalk brood
if mummies are still contained in capped cells, shake comb = mummies will be heard rattling in the cells
visual detection of chalk brood
beekeeper can diagnose based on hard shrunken chalk like mummies
cultivation of chalk brood
with potato dextrose and yeast extract 30 degrees
chemical treatment of chalk brood
little effect - spores destroyed with ethylene oxide
Control of chalk brood:
- Re-queening: from chalk brood-free colony recommended
zoonotic fungus remember zoontoic
stone brood
what broods does stone brood affect:
- uncapped and capped broods
- larvae and adult bees
- affect the head of the larve*
predisposition to stone brook:
chilly and wet climate
most common fungus of stone brood
- aspergillus flavus
- A fumigatus which is less common
colour of stone brood
yellow/ grey green
where is stone brood found
in soil and cereal products - may cause resp diseases in other animals
pathogenesis of stone brood
per os by feeding
what form on the surface of larvae in stone brood
- conidiophores
- containing spores
- false skin forms within 2-3 days
symptoms of larvae infected with chalk brood
- white and fluffy then turn brownish green yellow and STONE HARD
- No smell of dead larva
colour of A.flavus stone brood
yellow green
colour of A. fumigatus stone brood
gray green
colour of A.niger stone brood
black
treatment of stone brood
- no effective method
- kill infected colonies and moult wax - 30 mins at 60 degrees
biohazard risks of stone brood
aflatoxins are carcinogenic if inhaled or ingested
is stone brood notifiable
only in several countries
Nosemosis affect ?
- adult bees (worker, queens and drones)
When can Nosemosis be infected?
after emerging
Pathogens of Nosemosis:
- Nosema ceranae
- Nosema apis
Infective stage of Nosemosis ?
- Spore
what are spores in Nosemosis resistant to ?
- environmental degradation
- retain their viability for > 1 year
Pathogenesis of Nosemosis:
- spores after 5 days at 30degree, voided in the excreta of the bee
wich time of the year do you see symptoms of Nosemosis:
- autumn
- winter
- sometimes early spring
Symptoms fo Nosemosis:
- dysentry
- unable to fly and may crawl about the hive entrance or stand trembling on top of the frames
- signs of faeces on combs during winter with may be dark and scaly in cells
What happens with infected queens and workers in Nosemosis:
- queens: egg laying and die within 1-2 weeks
- workers: start to forage earlier
What is the most globally prevalent honeybee:
Nosema Ceranae
Diagnosis of Nosemosis:
- microscopic examination of digestive tract of dead adults
- PCR
- detection of spores
Which staining do we use in diagnose of Nosemosis?
methyl blue staining
Treatatment of Nosemosis:
- Fumagillin (25 mg active per litre of sugar syrup) antibiotic preferably at time when colony likely to encounter stress condition, such as during long winter / rainy season
- should disinfect heavily infected colonies
