16 May 2013

Basic Assessment notes - Part 5 : Disease and Pests

The last section of the syllabus is important, but these notes are brief - mainly because the information is readily available online at Beebase and it seems a bit pointless to paraphrase the experts.

If you are researching bee pests and diseases please follow the appropriate links and read more. Take your time to learn this subject, your bees deserve to be kept safe and healthy.

Beekeepers should, once they are sure the colony has a laying queen, inspect for brood irregularities and the condition of the bees they can see, rather than concentrating solely on the what is right. They should also be able to recognise symptoms of the most common diseases of adult bees.

It is good practice to inspect for disease twice a year - do this by shaking, or brushing, the bees off every single frame and check both sides of each comb very carefully.

If you think your bees have disease such as nosema, amoeba, or acarine your BKA's microscopist can probably check a sample for you. You can also send a sample to NBU at York. In both cases you will need to collect 30 bees. The easiest way is to close the hive entrance for a few moments, then put a large matchbox (or similar-sized container) in front of the entrance when it's re-opened - you will catch bees on their way out. When the box is full it should contain 30 bees. It's best to pop the box in the freezer before putting them in the post.

For pesticide poisoning the sample should contain at least 200 bees. Follow these instructions.

The Candidate will be:
5.1 able to describe the appearance of healthy brood;
A picture speaks louder than words:

Image ⓒ Notes from a Small Apiary
5.2 able to describe the signs of the bacterial diseases American Foul Brood (AFB) and European Foul Brood (EFB), the fungal disease Chalk Brood and the viral disease Sac brood;
Check brief descriptions within this blog's Beekeeping Glossary and read, very carefully, the information from Beebase by downloading the leaflet from Beebase.

DEFRA Advice (quote):
Precautions to take if you suspect foul brood in your hives
  • Close the hive. (only if the colony is dead)
  • Reduce the hive entrance to prevent robbing (do not close completely if colony alive -  diagnosis may be negative) - take other steps if necessary.
  • Disinfect your beekeeping equipment and gloves before examining other colonies, or if you use disposable gloves, select a new pair.
  • Either;
    • Contact the NBU immediately. An inspector will contact you as soon as possible and arrange a visit to your apiaries if necessary.
    • Send a whole comb (well wrapped to prevent leakage of honey) or a tube (available from the NBU, your ABI or some local associations) containing suspect diseased larvae to the NBU. Don’t forget to include your name, address, apiary location (OS map reference) and the hive identity.
    • If you have confirmed the presence of AFB/EFB using an Lateral Flow Device (LFD kit), send the positive kit and a larval sample to us.
  • Do not remove any hives, bees or equipment from the site until the disease (if confirmed) has been controlled. This is a self imposed 'Standstill' which is a requirement under the legislation.
American Foulbrood (Paenibacillus larvae larvae) kills larvae after capping.
Symptoms of AFB :
The characteristic disease signs of AFB include some or all of the following:
  • Uneven or 'Pepper-pot' brood pattern
  • Sunken, greasy or perforated, darkened cell cappings
  • Roping, sticky larval remains when drawn out with a matchstick
  • Dark "scales", which are difficult to remove from cells
European Foulbrood (Melissococcus plutonius) is an early disease, affecting early, uncapped, larvae.
Symptoms of EFB :
An infected colony may show some or all of the signs below: 
  • Erratic or uneven brood pattern
  • Twisted larvae with creamy-white guts visible through the body wall
  • Melted down, yellowy white larvae
  • An unpleasant sour odour
  • Loosely-attached brown scales
Unlike AFB, the remains of larvae that die from EFB do not rope when drawn out with a matchstick.
Chalkbrood is common in colonies under stress or a genetic problem. Is typified by dried out of mummified larval corpses. Improve conditions and/or re-queen. (pdf Edinburgh & Midlothian BKA)

Sac Brood is typified by 'chinese slipper' larvae - the larvae lay in the wrong direction, the tail outermost in the cell, with the tail slightly curved upwards like the toe of a traditional Chinese Slipper. Requeening is best course of action. (Fera info page)

5.3 able to describe methods for detecting and monitoring the presence of varroa (a mite) and describe its effect on the colony including awareness of the effect of associated viruses;
Using an open mesh floor with a monitoring tray beneath it is the least stressful means of monitoring a varroa drop, although it can be wildly inaccurate.
Leave the board in for a few days, then the average daily drop rate can be put into the Beebase Varroa Calculator, which will indicate whether treatment is urgent or not.

Mites may be seen on bees, but will more likely be found within brood, especially drone cells. The longer development suits varroa. Drone frame traps can be used to encourage drone brood raising. The drone brood can be removed once the cells are sealed, and destroyed - along with mites sealed in cells. (There is some concern that too frequent drone brood removal has a detrimental effect on queen mating - fewer drones available.)

Deformed Wing Virus (DVW) is exacerbated by the presence of varroa. (Article in Science Daily)
  • "Deformed Wing Virus is naturally transmitted in bees through feeding or sex but the mites change the disease so it becomes more deadly, shortening the bees' lives."
Parasitic Mite Syndrome (PMS) is caused by varroa. Quote from Loudounbee.org
  • Colonies that are apparently very healthy and productive suddenly experience a sudden decrease in adult population often resulting in the total loss of the colony. Plenty of food stores are often present, but very spotty and unhealthy brood are observed. This phenomenon can occur at any time during the bee year, but is most often experienced in the autumn. To prevent the typical autumn die-off associated with BPMS, it is critical to control the varroa mite infestations earlier in the beekeeping year. In a survey conducted at Beltsville Bee Lab, it was reported that 28% of the colonies diagnosed with BPMS contained both varroa mites and tracheal mites. However, it is believed that varroa mites are the principle mite species associated with syndrome. No specific pathogen has yet been identified. BPMS mimics other diseases. It may be connected with the vectoring of one or more viruses by both mites, such as acute bee paralysis virus or Kashmir virus. It has been shown that varroa mites transmit viruses that can be more devastating than their own feeding activities.
5.4 aware of acarine (a mite) and nosema (a fungus) and their effect upon the colony;
Acarine is the tracheal mite Acarapis woodi. Believed to have been responsible for what was called Isle of Wight Disease, which started in 1906 and killed a high proportion of British bees, both kept and feral. The mite lives within the tracheae (tracheas?) of infested bees. Symptoms include large numbers of bees 'shivering' outside the hive entrance. (Fera info page)

Nosema apis - bacterial parasite infection can be indicated by dysentery, causes colony to dwindle. Can be treated by shook swarm, thymol syrup be effective.

Nosema ceranae - a newish bacterial parasite disease that causes colonies to dwindle, more often that not this will be later in the year. No other obvious symptoms.

Nosema on Fera/Beebase

5.5 able to describe ways of controlling varroa using integrated pest management techniques;
Read the Beebase booklet "Managing Varroa"
  • Monitor varroa drop - treat with varroacide as/when advised by Beebase calculator.
  • Drone brood removal  - varroa prefer drone brood, longer development.
  • Uncap drone brood to estimate varroa load.
  • Shook swarm - leaves infested brood behind + brood break so can use OA.
  • Artificial swarm - brood break.
  • Queen trapping - to enforce brood break.
  • Using VSH queens - SHCG - Swindon Honeybee Conservation Group

5.6 aware of the current legislation regarding notifiable diseases and pests of honeybees;
Any beekeeper who thinks their colony or colonies has a foulbrood infection is required, under EU regulations, to report it to the NBU Inspectorate - usually via their Regional Bee Inspector or Seasonal Bee Inspector.

Notifiable pests of honeybees are Small Hive Beetle (Aethina tumida) and Tropilaelaps.(Tropilaelaps miles)

Small Hive Beetle (Aethina tumida) was discovered in Italy in autumn 2014, apiaries in the wider area centred on Gioia Tauro and in Sicily continue to be monitored by officials.

Tropilaelaps miles cannot survive broodless periods.

The Inspectorate would like to be made aware of confirmed sightings of the Asian Hornet (Vespa velutina nigrithorax) but this is not a legal requirement and they don't need to be inundated with false sightings.

V. velutina is a serious threat. It is a vicious, aggressive, insect and will chase people as well as being capable of destroying colonies of bees. If you suspect you have caught one of these hornets you should put the insect in your freezer and send a photograph to Non Native Species Secretariat to:- alert_nonnative@ceh.ac.uk They will tell you what to do next.

Asian Hornet has spread into Spain and Portugal, as well as Belgium and north west Italy - check this interactive map.

5.7 aware of whom to contact to verify disease and advise on treatment;
The National Bee Unit's Regional or Seasonal Bee Inspectors, who can be contacted through this page on BeeBase.

5.8 able to describe how comb can be stored to prevent wax moth damage;
  • A stack of boxes containing used but empty brood frames can be sealed within either a plastic bag, plastic sheeting or insect-proof netting, then kept outside where they can be frosted. Frost will kill wax moth eggs and larvae.
  • Individual frames can be placed in a domestic freezer for 48 hours.
  • Stacks of boxes containing brood frames can be treated with acetic acid, but this can damage frame wires. Sulphur candles can also be used.
  • Honey frames, which have never contained brood, are unlikely to be attacked by wax moth.
5.9 able to describe how mice and other pests can be excluded from the hives in winter.
  • Using a reduced entrance or mouseguard will keep them out. This could be a strip of perforated metal or a piece of wood with nails or screws inserted vertically at bee space intervals.
  • Wasps may try to hibernate within a hive, they can be deterred by using a reduced entrance. DEFRA recommends that, when Asian Hornets arrive in Britain, entrances should be reduced to 5.5mm in height.
  • Green Woodpeckers can learn to attack hives, and will do so more often when the ground is frozen and they can't reach ants (their preferred food). A chicken wire** cage can be put round the hive, there is some success using plastic bags - either the woodpeckers can't grip them or their beaks cannot easily penetrate the flexible plastic.

** Avoid draping fruit cage netting loosely over a hive - birds' legs can get tangled in it, they will starve or be easy prey for predators.

There are 'notes' for each section of the 'Basic Assessment' syllabus:
BBKA Basic Assessment : Syllabus 2013
Basic Assessment notes - Part 1 : Manipulation of a Honeybee Colony
Basic Assessment notes - Part 2 : Equipment
Basic Assessment notes - Part 3 : Natural History of the Honeybee
Basic Assessment notes - Part 4 : Beekeeping
Basic Assessment notes - Part 5 : Disease and Pests
BBKA Basic Assessment notes : On the day


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