3.18 - Causes, signs, treatment of other brood diseases Flashcards
1
Q
What type of pathogen is chalk brood? 1
A
Fungus
2
Q
What does chalk brood affect 1
A
Chalk down death after capping
3
Q
When is chalk brood most likely to flare up and why 2
A
- Typically flares up in Spring when colonies are expanding
- If there are spores in the hive, and larvae are mildly chilled to 30˚C, brood becomes more susceptible
- Spores infect the brood from contaminated worker mouth parts and germinate in the hind-gut of the larva
4
Q
How long is chalk brood infective
A
Condition endemic and spores infective for 3+ years
5
Q
Chalk brood signs 5
A
- Affects sealed brood - perforated cappings
- Mummified white larvae with mouth parts forming characteristic protuberance in centre. Often take on hexagonal shape of cell before shrinking, at which point bees removed them.
- Mummies on floor out outside hive; easily shaken out, leaving pepperpot
- Chalky mummy turns grey to blacks as fungus sporulates
6
Q
Chalk brood lifecycle 6
A
- Larva ingests spores it with its food.
- Needs COOL to germinate 30˚C, and CO2 of hindgut
- So on pupation the spores germinate in hindgut.
- Hyphae (threads) grow through gut wall, body and cuticle to produce a mycelium, a swollen mass of fluffy white fungus with small yellow lump where head used to be.
- Mummy turns from white>grey>black.
- Dark mummies produce vast numbers of sticky, resistant spores which remain infective for 3+ years.
7
Q
How to avoid chalkbrood 7
A
Avoid
- Making up queen mating nucs in little boxes with too few bees;
- Chilling brood as we inspect, esp on cold, wet windy days
- Dividing colonies leaving too few bees to cover brood;
- Spreading brood early in season
- Over-stimulating brood rearing in spring -> too much brood, not enough HB
- Transferring combs from infected colonies.
- Damp apiary sites
8
Q
Chalk brood treatment 3
A
- Move onto clean comb with shook swarm/bailey frame change.
- Requeen - some strains may be more resistant than others
- Minimise stress
9
Q
Impact of Chalkbrood on colony 3
A
- Rarely fatal to colony
- Can depress honey yield
- Colonies produce fewer drones because they are on extremities
10
Q
How would a beekeeper recognise chalk brood?
A
- (Caused by fungus Ascosphera apis.)
- White, fluffy fully-grown larvae or pre-pupae with tiny yellow ‘heads’, seen when bees remove the cappings. Look like a white ‘plug’ filling the cell.
- Plug starts soft and fluffy but hardens to a solid lump known as a ‘chalk brood mummy’.
- Bees try to remove the mummies.Hard mummies on the floor of the hive or below the entrance again may be in large numbers. Can be white or mottled grey.
- Mummies differ from stone brood mummies as they are softer and crumble when handled.
- Pepper-pot appearance of the brood.
11
Q
How does this differ from Stone Brood?
A
- Stone brood also caused by a fungus (Aspergillus flavus or Aspergillus fumigatus).Very uncommon.
- Fungus works in same way as chalk brood but larvae die after the cell is capped.
- Become very hard turning yellow then green when spores form.
12
Q
What factors are known to increase the chances of the presence of chalk brood? (4)
A
- Very common in the Spring when colonies expanding fast resulting in there being too few bees to keep all the brood warm.
- Slight chilling does not kill the larvae but favours growth of fungus.
- Small weak colonies susceptible as not able to retain heat so well.
- Avoid cool, damp conditions and inadequate ventilation
- Beekeeper should avoid giving extra brood to colonies that cannot cover
13
Q
What action can a beekeeper take to reduce chalk brood in a hive? (3)
A
- Have young queens and strong healthy colonies going into winter.
- Have adequate ventilation and avoid placing hives in damp, chilly areas.
- Frames containing a lot of chalk brood should be destroyed and replaced with new foundation
- If problem continues, try re-queening but this is not always effective.
- Essential oils including cinnamon oil and thymol have been found to inhibit the growth of chalk brood fungus,
14
Q
Give the cause of sac brood.
A
Morator Aetulas
Sac brood virus
15
Q
List the signs of the disease (5)
A
Virus kills the larvae after the cell is sealed.
- Colour goes from yellowish to light brown.
- Bees remove the cell cappings to reveal a fluid filled bag or ‘sac’.
- As it dries it forms a dark brown flattened scale shaped like a gondola or Chinese slipper.
- In the early stages when the cappings are not fully removed, the cell contents may be sticky and fluid but not ropey thus ruling out AFB.
- Pre-pupa dies inside the cell.
