Module 3 - Paper 1

  • Posted By: jenifer
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Varroa destructor on the head of an emerging bee

With Module 1: Honey Bee Management safely tucked under my beekeeping belt in 2017, this year I've chosen to study Module 3: Honey Bee Pests, Diseases and Poisoning for my correspondence course. I'm giving myself the full year to learn as found it quite challenging last year to find enough hours in the day to spend time doing my research before thinking about sitting the exam.

1. What honey pests might be arriving in our shores in the future?

  • Asian Hornet Vespa velutina - 2 confirmed sightings already in England (Woolacombe, Devon and Tetbury, Gloucestershire) [Update 13/04/18: 1 confirmed sighting in Bury, Lancashire traced back to Boston, Lincolnshire.]
  • Small Hive Beetle Aethina tumida
  • Tropilaelaps mites - Tropilaelaps clareae and Tropilaelaps mercedesae - these two are seen as a threat to our honey bees than Tropilaelaps thaii and Tropilaelaps koenigerum

2. List the notifiable bee diseases and pests in the current UK and European legislation.

Under the following UK orders:

  • The Bee Diseases and Pests Control (England) Order 2006
  • The Bee Diseases and Pests Control (Northern Ireland) Order 2007
  • The Bee Diseases and Pests Control (Scotland) Order 2007
  • The Bee Diseases and Pests Control (Wales) Order 2006

the following diseases and pests are cited as being notifiable:

  • American Foul Brood - Paenibaccilus larvae
  • European Foul Brood - Melissococcus plutonius
  • Small Hive Beetle - Aethina tumida

or any species of the Tropilaelaps mite.

Under the EU Animal Health Framework for Bees of the EU Directive 92/65/EEC (Bailai Directive), the following are listed as notifiable diseases and pests throughout the European Union:

  • American Foul Brood
  • Small Hive Beetle
  • Tropilaelaps mites

3. Who do you notify if you suspect one of your colonies has a notifiable disease or pest?

The local bee inspector (authorised agent for the National Bee Unit) who will arrange a visit to examine the suspected colony. Alternatively, a beekeeper can notify the National Bee Unit direct to arrange for the local bee inspector to visit and examine.

4. Why are combs with suspected EFB no longer routinely sent to the National Bee Unit?

Melissococcus plutonius is now endemic in this country and the local bee inspector can diagnose EFB in the field. A field test kit using a Lateral Flow Device allows the detection of EFB in samples of infected tissue with a high rate of accuracy. This kit uses an antibody test that reacts specifically to the antibodies associated with EFB. By testing in the field, it enables immediate treatment to be taken.

5. List other diseases or conditions with which EFB can be confused.

  • American Foul Brood - some strains of which kill uncapped larvae and form scales. Unlike EFB scales, AFB scales are difficult to remove. The brood pattern also looks 'pepper pot' in appearance. Sometimes EFB larvae make it through to the sealed brood stage before dying, when there may be greasy, perforated sunken cappings similar to AFB. However the contents underneath the cappings are usually quite different. Unlike AFB, EFB doesn't 'rope' when pulling out with a matchstick.
  • Chalk Brood - caused by the fungus Ascosphaera apis. In the early stages of the disease, the larvae and pupae are misshapen and discoloured similar to EFB.
  • Chilled brood - which causes dead brood usually present in all stages, especially at the edge of the brood nest - unsealed brood turns very dark brown or black in colour before drying up.
  • Parasitic mite syndrome (PMS) - caused when there is a high varroa level in a colony. The brood starts to show a range of disease symptoms. Dead larvae/pupae which die at the uncapped brood stage discoloured brown or black, watery or firm, eventually drying to a scale similar to EFB which can easily be removed. Newly emerged bees are often deformed or have deformed wings. As with EFB, there will be a poor brood pattern.

6. What are sentinel apiaries?

These are apiaries specifically selected across England and Wales by the National Bee Unit in areas 'at risk' which are considered to be vulnerable to the introduction of non-native species. These sentinel apiaries are randomly selected to monitor and check for exotic pests. The beekeepers regularly send in samples of floor debris to the National Bee Unit to examine for signs of Small Hive Beetle and Tropilaelaps mites or any other unknown non-native exotic pests found.

7. Where are they likely to be situated?

At areas of high risk of where exotic pests are likely to arrive in the country, for example:

  • Military and civilian airports
  • Freight depots
  • Shipping ports
  • Bee importers and surrounding apiaries

There are 8 regions in England and Wales with 15 sentinel apiaries within each region.

8. What might the following pests possibly be confused with, and how would you distinguish them?

i) Asian Hornet

  • Queen up to 30 mm long, worker up to 25 mm long
  • Legs yellow at the ends
  • Dark brown / black abdomen with a yellow/orange band on 4th segment
  • Head dark from above, orange from front
  • Dark coloured antennae
  • Entirely black velvety thorax
  • Never active at night

Similar to:

a) European hornet (Vespa crabro)

  • Queen up to 35mm long, worker up to 30mm long
  • Legs brown at the ends
  • Yellow abdomen marked with brown on the upper
  • part, not banded
  • Head yellow from above, yellow from front
  • Yellow antennae
  • Thorax black with extensive brown markings
  • May be active at night

b) Giant wood wasp (Urocerus gigas)

  • Larger than Asian hornet, female up to 45mm long
  • Legs yellow
  • Distinctive yellow and black banded abdomen
  • Long cylindrical body unlike Asian hornet which has an obvious waist
  • Long yellow antennae
  • Female has an obvious long sting-like ovipositor used to lay eggs in trees

c) Hornet mimic hoverfly (Volucella zonaria)

  • Abdomen has more yellow stripes
  • Legs darker
  • Only one pair of wings (hornets/wasps have two pairs)
  • Large globular eyes

d) Median wasp (queen) (Dolichovespula media)

  • More extensive yellow and orange colouration on abdominal segments
  • Yellow markings on thorax
  • Wasp queen is smaller in size

ii) Small Hive Beetle

  • Larvae has 3 pairs of legs near the head
  • Rows of spines on back
  • 2 large spines extending at the rear of the larvae
  • Larvae causes honey to ferment, hive becomes 'slimed out'
  • Prefer to eat eggs and brood, damages brood nest
  • Lifecycle starts in the hive
  • Mature larvae leave hive and pupate close by in soil

Similar to:

Wax Moth (Galleria mellonella)

  • Larvae has 4 pairs of legs on abdomen
  • Thicker wax gland
  • Larvae leave behind webbing mass with tough white cocoons on the frames and hive body
  • Lifecycle all takes place inside the hive

iii) Tropilaelaps

  • Elongated body
  • 4 pairs of legs
  • Moves very quickly across brood combs - catches beekeeper's eye
  • Mites hide in brood cells

Similar to:

a) Varroa destructor

  • Mites larger, crab-shaped, wider than they are long
  • 4 pairs of legs towards the top of its body (first pair play sensory role)
  • Move relatively slowly
  • Adult mites are an external parasite seen on bees

b) Braula coeca

  • Braula is a wingless fly and therefore only has 3 pairs of legs either side of its body
  • Seen around mouth parts of bees as it steals food, especially from the queen.

c) Melittiphis alvearius (pollen mite)

  • Smaller than Tropilaelaps mites
  • 4 pairs of legs either side of its body
  • Scavengers causing no harm to honey bees or brood

9. a) Describe the similarities and differences in the signs of EFB and AFB.

American Foul Brood

  • Notifiable disease – confirmed cases always destroyed
  • Bacterium (spore-forming)
  • Paenibaccillus larvae
  • Affects sealed brood
  • Kills larvae after sealed in cells
  • Two stages:
    1. Vegetative stage (rod-shaped)
    2. Spore stage
  • Sunken wax cappings/greasy looking
  • When sunken cappings, larvae dark brown, sticky mass
  • The remains can be drawn out slowly with a matchstick into a mucus-like brown thread ('ropiness') usually >2 cm
  • Brood pattern 'pepper pot' appearance as more sealed brood affected die
  • Unpleasant smell caused by larvae decomposition and prescence of other bacteria
  • Sometimes tongue-like proboscis  of dead pupae protruding upwards in cell
  • Final stage, very dark brown, rough scale on side wall of cells that bees unable to remove
  • Can see scales when comb held towards light

European Foul Brood

  • Notifiable disease - confirmed cases, if mild, can be treated with antibiotics, but preferred method is carrying out a shook swarm, otherwise destroyed like AFB
  • Bacterium
  • Melissococcus plutonius
  • Affects unsealed brood
  • Kills larvae before sealed in cells
  • Larva moves inside its cell
  • instead of healthy 'C' shape.
  • When the larva dies it lies in an unnatural position – twisted around cell wall, across the mouth of cell or stretched out lengthways.
  • Gut of infected larvae may be seen through transulsent body – creamy/white colour caused by bacteria
  • Gut colour of EFB affected larva lacks the yellow which is the pollen in the gut, but the bacteria consume it
  • EFB causes a larva to starve as it robs it off its food.
  • Dead larvae appears melted, turning yellow/brown
  • Some larvae may die after cells capped, could see sunken cappings and apears similar to AFB - contents can 'rope' but it isn’t as definite as AFB and breaks off easily
  • Patchy and erratic looking brood pattern when high number of larvae dying
  • Unpleasant smell caused by larvae decomposition and prescence of other bacteria
  • Final stage, forms into dry and rubbery brown scales on side wall of cells that can be removed

EFB and AFB do not affect sealed or unsealed brood - both affect a young larva which then dies at different times. AFB larva dies after capping. The larva is infected early but dies. EFB larva dies before capping usually - and it is those which die after capping which re-infect because the larva defecates once cell is capped, the gut contents are voided into the cell - full of spores - which nurse bees then clean up and pass to young larvae when feeding them.

9. b) Explain the life cycle of AFB and EFB and describe how each disease develops within the larvae and within the colony.

American Foul Brood

Larvae up to 3 days of age ingest the Paenibaccillus larvae bacterium spores in contaminated brood food given to them by the nurse bees. Larvae less tan 1 day old are most at risk. The spores germinate in a larva's mid-gut into the vegetative stage a day after ingestion. The rod-shaped bacteria penetrate the gut wall entering the tissues where they proliferate at a fast rate until the larva dies. Death typically occurs after the cell has been capped, usually during the last 2 days of the larval stage or the first 2 days of the pupal stage. After capping, the bacteria transforms into the spore stage and the larvae die. The larvae becomes dark brown in colour and decays into a sticky mass. As it decays, there may be a smell associated with decomposition and presence of secondary bacteria. The final stage, after about a month, dead larvae dry to dark brown scales that stick firmly to the cell walls which the bees are unable to remove. Each scale contains millions of spores.

Within the colony, it may appear weak due to the loss of bees and may appear aggressive. The brood pattern will have a 'pepper pot' appearance as well as more sunken sealed brood cappings.

Where the bees have uncapped the cells, there will be larval remains which are a dark brown, sticky mass that can be drawn out into a mucus thread. When dry the dark scales may be seen when held up to the light on the lower sides of the cell. If there are pupae remains, the tongue-like proboscis of dead pupae may sometimes remain intact, protruding upwards from the bottom edge of the cell.

European Foul Brood

Young larvae ingest the Melisoccocus plutonius bacterium in contaminated brood food given to them by the nurse bees. The bacteria multiplies in a larva's mid-gut and the multiplying bacteria competes with the larva for food causing the larva to die of starvation usually when 4-5 days old, 1-2 days before its cell is capped. The dead and dying larvae lie in unnatural and often distorted positions in their cells and lose their pearly-white colour and segmentation and turn a yellow/brown colour which eventually dries out becoming a rubbery scale that sticks to the cell wall. The workers try to remove the dead/lying larvae and become infected with the disease themselves. Infected larvae that survive to pupate, discharge their gut contents into the cell. This is cleaned away by the workers who pick up the bacteria and subsequently pass on to others.

Within the colony, the disease can develop over a long period of time and appear to disappear in the spring (see 9[c] below). EFB usually weakens a colony and can also kill a colony.

If the disease is confirmed at the end of the summer or in the autumn, at the time when the winter bees are being reared, a patchy brood pattern would indicate a high level of disease.

9. c) If EFB is present in a colony in spring why does it seem to disappear in the summer?

In the spring, a colony is building up in strength and there are not enough workers to remove the larvae quick enough and as the colony reduces in size later in the year, there are more workers able to clean out contaminated cells and therefore it seems to disappear in the summer.

9. d) Describe how these diseases might be spread from colony to colony.

The biggest culprit is the beekeeper spreading diseases by using contaminated comb, honey or tools in healthy colonies. Also by transferring brood frames between hives and using old comb for several years without replacing. Old wax or comb shouldn't be left at the apiary and any second-hand equipment should be sterilised to avoid contaminating colonies.

The bees themselves can also spread disease when drifting is allowed in the apiary by not having sufficient space between each beehive to prevent. Honey bees can also rob out other colonies. The bees take back the contaminated honey to their colonies.

Infected swarms brought into the apiary can spread disease to other colonies, so they should be kept well away in isolation until satisfied they are disease-free before introducing into an apiary.

Beekeepers who move their bees, for example to the heather, could spread disease if they move infected colonies. Healthy colonies sited close by would be vulnerable to the disease. And vice-versa if bees were moved near to apiares infected with disease.

Any dead colonies can be a source of infection so they should be closed to prevent stores being robbed before examining the brood frames for signs of any disease.

Also, AFB spores can remain viable for decades in comb or hives parts and can survive extreme hot/cold temperatures.

The spores can also remain in honey for years.

10. a) How does a Bee Diseases Inspector deal with a hive with AFB or severe EFB?

All cases of confirmed AFB and severe cases of EFB are both dealt with the same way by destroying the infected colony under supervision of the bee inspector.

The bees are first killed by sealing the hive and pouring a cupful of petrol down the a centre hole in the crown board. This kills the bees in seconds.

A large pit is dug beforehand and all the frames of comb and any zinc queen excluders are put in the pit and set alight. Once the fire goes out, the pit is filled in.

The hive itself can be sterilised by scorching throroughly with a blowtorch. Smoker, hive tool, wellies are washed throroughly in washing soda, together with beesuit throroughly washed.

10. b) How would mild EFB infection be dealt with?

There are three actions available:

  • Shook swarm
  • Antibiotic treatment
  • DestructionAntibiotic

The preferred method of the bee inspector to deal with a mild case of EFB, is to carry out a shook swarm which has shown to be effective as it completely removes contaminated comb by transferring the colony straight onto new comb and avoids using antibiotics. The contaminated combs are then destroyed by burning.

A shook swarm is best carried out in the spring during a nectar flow. If no nectar flow, the colony will need feeding sugar syrup (1 pint water : 2 lb sugar) to encourage them to build wax.

In a report by DEFRA in 2006, it showed that the shook swarm method was more successful than treating with antibiotics.

Alternatively, the bee inspector can treat a colony with mild EFB with the approved antibiotic oxytetracycline (OTC) which is issued on prescription and carried out at the time the disease is confirmed. The bee inspector will inspect the colony again 6 weeks later and if no suspected infection the bee inspector is likely to recommend that the beekeeper carries out a shook swarm to help prevent re-occurrence. If EFB is still present, in most cases, the colony will be destroyed. The use of antibiotics is not the solution because of the risk of EFB recurring and a build up of antibiotic resistance as well as the risk of residues in hive products.

The bee inspector may order a colony to be destroyed if it is weak or too small for other treatment methods or too heavily infected to respond to treatment. The colony can also be destroyed at the request of the beekeeper.

It should be remembered that a beekeeper must by law keep records of any veterinary treatment administered to a colony for five years, even if the bees move to another beekeeper.

10. c) Describe how to use a lateral flow device for EFB and AFB.

There is a Lateral Flow Device (LFD) kit for both EFB and AFB - they are not interchangeable. Each kit uses an antibody test that reacts specificially to the antibodies associated with each brood disease.

  • Extract a larvae from its cell showing suspicious symptoms with the spatula provided in the kit
  • Unscrew the lid of the buffer bottle and use the spatula to drop the sample into the bottle
  • Replace the lid and shake the contents for about 20 seconds
  • Unscrew the lid and use the pipitte to remove a sample from the bottle. It's best to do this straight away so that the larvae sample doesn't separate in the suspension
  • With the LFD horizontal, place 2-3 drops onto the sample well and wait for 2-3 minutes for the results to show.

Blue line at C (control line) - Result negative.

Blue lines at C + T (Test line) - Result positive.

If neither the C or T show, then test again using a different LFD.

10. d) In the USA antibiotics are routinely used, both prophylactically and to treat AFB. What does this mean and what are the dangers of such a practice?

I had to look up 'prophylacic'. In the Collins dictionary it means to prevent or guard against disease.

Because antibiotics are routinely used, there will be a build up of resistance and therefore the antibiotics being used will no longer be effective in treating colonies confirmed with American Foul Brood.

11. Give an account of the statutory legislation as it applies to notifiable diseases and pests; include information and standstill notices and legislaton about the importation of honey bees.

Under the Bee Diseases and Pests Control (England) Order 2006 (separate orders in Northern Ireland, Scotland and Wales) any beekeeper who suspects the presence of either American Foul Brood, European Foul Brood, Small Hive Beetle or Tropilaelaps mites in a colony must contact their local bee inspector or the National Bee Unit to have the colony officially examined.

As soon as a beekeeper notifies the the local bee inspector of a suspected disease or pest, the colony should be closed (minimal gap for foraging bees to return) and and no bees, combs, bee products from the beehive or anything liable to spread disease from that apiary should be removed.

In the case of suspected AFB or EFB, the bee inspector will arrange with the beekeeper a visit to the apiary to test for foul brood disease.

If a notifiable disease is confirmed, a Standstill Notice is served on the beekeeper prohibiting the moving of any bees, equipment or beehive products from the apiary.

Standstill Notices will remain in force until the bee inspector has returned to re-inspect the apiary and is satisfied that the bees are not infected with any further notifiable disease or pest (usually remain in force for a minimum of six weeks).

An apiary inspection report detailing the beekeeper’s address, the number of colonies in the apiary, location and condition of the colony is sent to the National Bee Unit laboratory together with the bee inspector's recommendation on control action.

In the case of AFB, a Destruction Notice is issued. The infected colony - all its bees, frames, combs, honey  are burned in a pit dug in the apiary under the supervision of the bee inspector.

The beehive parts must be sterilised by scorching the woodwork with a blowtourch.

In the case of EFB, either a Destruction Notice (in severe cases) or Treament Notice (in mild cases) is issued. If, after treatment, EFB remains, a further notice can be issued requiring destruction.

Beehives or equipment may be marked for identification purposes and the beekeeper or any other person must not tamper or interfere with the identifying marks.

If Small Hive Beetle or Tropilaelaps (adults or larvae) is suspected, samples are sent to the National Bee Unit for examination in a sealed container after they have been frozen for 24 hours.

If a notifiable pest has been confirmed, DEFRA's Contingency Plan for Exotic Pests and Diseases of Honey Bees will be invoked and emergency searches and control measures will commence immediately.

Where there is an area with confirmed disease or pests, the National Bee Unit can declare the area to be infected.

The Orders also cover the legal requirements for importing honey bees and bumblebees from countries inside and outside the European Union. The Order relates specifically to Apis mellifera and Bombus spp from certain third countries.

On arrival at the destination specified on the accompanying Health Certificate, all queen bees are transferred to new queen cages before introduced into colonies. The cages in which the queens travelled from their country of origin, plus attendant bees and any other material, must be sent to the National Bee Unit for examination for any notifiable disease or pest. After examination, these will be destroyed.

In the case of species of Bombus being imported into England the owner in charge of the bees must ensure the containers in which they were transported from the country of origin and all material that accompanied the bees are destroyed either during or immediately at the end of the lifespan of the imported colony.

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Copyright: 

The image used has been published under the terms of a Creative Commons License and is attributed to Gilles San Martin.