Pathogens, Parasites, and Pests of Honey Bees

Adult Honeybee Diseases & Pathogens

Nosema Diseases

• Nosema apis
• Nosema ceranae

Dysentery

Pesticides

• Neonicotinoids
• Organophosphates
• Pyrethoids
• Fungicides

Nosema apis and Nosema ceranae

• The most common adult bee disease.
• N. ceranae has overrun N. apis in European honeybees.
• A bee protozoa - infects the gut of GI tract bee.
• 30 million spores in a single bee after 2 weeks of infection.
• Can kill an overwintering colony.

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Why Nosema matters so much...

• Greatly reduces the lifespan of all castes of bee. (by 50%)
• Thereby reduces honey yield (40%)
• Causes early queen supersedure
• Delays growth of bee population by reducing functioning of food/ brood gland of nurse bees
• Disruption of hormonal development, causing bees to age faster and forage earlier in lifecycle.
• Disruption of digestive enzymes, causing starvation.

Nosema symptoms

• Unable to fly or fly only short distances
• Trembling, stumbling, dragging legs on bottom board
• Feces on combs, top bars, outside walls
• K-wing deformity
• Not eating syrup when fed
• Abandoning colony, leaving queen and few workers

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Nosema�Symptoms

Treatment/management

• Good wax rotation practices
• Clean water
• Young queen
• Sunny site, shielded from wind but with adequate winter ventilation
• Emergency honey, or heavy sugar syrup (2:1)
• Clean comb; sterilize soiled comb with 10 % bleach and/or replace
• Reduce stress - no moving

Nosema Chemical Treatment

Fumagillin – produced by fermentation of Aspergillus fumigatus (commercial Fumagilin-B, contains Bicyclohexyl ammonium)

Dose: 166 mg daily for a colony for 3- 4 weeks in sugary syrup

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• Fed as a medicated syrup in fall and spring
• Must not be used during nectar flow
• Dosing level effective for both N. apis and cerena.

Dysentery

Result of poor food, fermented food, syrup with impurities; and long (usually late winter) periods of confinement in humid conditions.

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Signs: Sluggish bees, swollen abdomens, and yellow/brown fecal staining on hive walls

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Treatment: Provide winter exit; provide fresh heaviest syrup possible; clean or replace soiled comb

Pesticides: human-made disease

Neonicotinoids, Organophosphates, Pyrethoids, Fungicides

• High levels or acute exposure
• Low levels of exposure / chronic poisoning

Uptake into wax from affected water, pollen, nectar, and direct contact.

Acute symptoms --

• Sudden missing of house bees during ag. growing or public insecticide season
• Mass bee kill in front of hive
• Disorganized hive; Inappropriate queen supersedure
• Stores, especially pollen or waxed over

Honey bees get covered in pollen

Brood Diseases

• Bacterial Diseases
• American Foulbrood
• European Foulbrood
• Fungal Diseases
• Chalkbrood
• Viral Diseases
• Deformed Wing Virus
• Sacbrood Virus

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American Foulbrood (AFB)

The reason apiary inspection laws were passed.

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Cause: Paenibacillus larvae bacteria

- spore forming bacteria

• Young larva ingest bacterial spores when fed by nurse bees.
• The spores then germinate and grow rapidly. Death occurs as the pupal stage is reached.
• Dead bees melt into a coffee-brown gooey mass.
• Worker bees then try to remove the dead mass and become contaminated with dormant bacterial spores.

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Bacterial

American Foulbrood (AFB)

• The worker bees then carry the spores to others, and the spores end up in honey stores and fed again to new larva. Thus the disease is spread rapidly within the colony.
• Robbing and drifting bees can then also spread it to other colonies.
• Spores last eighty years in woodenware and in the environment.
• AFB is the most serious and contagious bee disease.

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Bacterial

• Perforations in the cappings
• Sunken cappings rather than domed caps
• Foul smell
• Shotgun brood pattern

A

F

B

Bacterial

• Dead brood is dark brown; Appears melted or gooey
• Matchstick test: body goo can be drawn out like taffy from comb (at least an inch) with a matchstick

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American Foulbrood (AFB)

Treatment: Tetracycling/Terramycin and Tylosin preparations can be used but complete recovery is never achieved

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Burn entire hive and cover burn pit.

@ 200 mg dusting with sugar powder at least 3 time per colony at 4- 5 days interval

European Foulbrood (EFB)

Bacterial

Cause: Melissococcus pluton bacteria

- non spore forming bacteria

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• Larvae are most susceptible to infection when they are less than 48 hours old
• Usually die while still in the 'C' coiled state.
• Poor nutrition and severe stress, as insecticide poisoning, often cause this disease to break out.
• The larvae first turn yellow then coffee brown in color.
• The disease is usually noticed in early spring, and to a lesser extent in autumn.

European Foulbrood (EFB)

• Bees die as larvae, not pupae, in uncapped cells.
• Body deflates and dries, does not get gooey.
• Still an infectious disease, spreads through robbing or honey sharing to other colonies.
• Slight sour odor

Treatment:

• Treatable with oxytetracycline (Terramycin). Does not cure the disease, prevents new infection.
• Terramycin cannot be used during nectar flow or with honey supers on.
• Prevent robbing of infected hive.

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Bacterial

European Foulbrood (EFB)

• The disease goes away on its own at the onset of a strong nectar flow.
• The beekeeper may control the disease by simulating a nectar flow (by feeding sugar syrup).
• The bacterium does not form long-lived spores that persist on hive surfaces.

Oxytetracycline:@ 200 mg dusting with sugar powder at least 3 time per colony at 4- 5 days interval

Chalkbrood

Cause: Ascophera apis fungus

• Usually does not destroy a strong colony.
• Can assist in killing off a weak one.
• Symptoms:
• Chalk-looking white/grey spongy bodies at entrance and in brood frames
• 4-day old larva most susceptible
• No registered fungicide treatments
• Treatment:
• Relocate from damp location to drier, sunnier spot
• Requeen if it persists
• Destroy infected combs

Fungal

C

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a

l

k

b

r

o

o

d

Viral Diseases� Deformed Wing Virus and Sacbrood Virus

Symptoms:

• Bees may be hairless or glossy as in old age.
• Bees crawling on the ground around the hive entrance, or trembling on the landing board unable to fly.
• Trembling could be a symptom of pesticide poisoning as well.
• In some cases the hive dwindles slowly away. In other cases it recovers.

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Treatment:

No specific treatment for a viral disease.

Requeening with good stock may help

Viral

Pests

• Tracheal Mites
• Varroa Mites
• Wax Moths
• Small Hive Beetles
• Ants, Skunks, Raccoons, Mice, Bears

Tracheal Mites

Cause: Acarapis woodi

• Microscopic in size.
• First infected American bees in mid-1980s.
• Infects trachea and sucks hemolymph (blood) from bee.
• Affects wintering bees more because they live longer. They can infest and re-infest until the high mite population causes the colony to perish.
• Deadouts full of honey can be symptomatic of tracheal mites.

Tracheal Mites

Unreliable symptoms:

• Dwindling populations.
• Weak bees crawling with K-deformed wings.

Positive diagnosis only by microscope.

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Tracheal Mites

Treatment Options:

• Crystal Menthol - difficult to administer effectively.
• Hygienic Queen Stock - breed survivor queens and bees.
• Mite Away II - formic acid treatment.

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Varroa Mites

Cause: Varroa destructor

The #1 threat to bees. It has been responsible for more recent beekeepers quitting apiculture than any other pest.

• The mite is small but can be seen with the naked eye. Mites are about the size of a pin head and are reddish/brown in color.
• More than 85% of the mites in a colony are in capped brood cells and not visible.

Varroa on adults�and on capped pupa

Varroa

• reduces flight activity of foragers.
• causes weight loss (6-25%).
• reduces lifespan (34-68%).
• reduces hemolymph volume (15-50%).
• damages exoskeleton in pupa if 5+ mites in a cell.
• shown to be involved with virus transmission to honeybees.

Varroa can be seen by eye, but are more easily counted by these methods:

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• A common method is using a sticky board, which is left underneath the screened bottom board of a hive for a period of 24 hours. The mites that fall onto the sticky board are then counted.

Varroa Treatment Options

Non-chemical:

Powdered sugar treatment

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Hard Chemical:

Apistan strips (fluvalinate) -becoming resistant

CheckMite+ (Coumaphos)

Formic Acid

Oxalic Acid (in UK only)

Apivar (Amitraz)

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Wax Moths

Galleria mellonella L. - Greater Wax Moth and Achroia grisella F. - Lesser Wax Moth

• The larval stages of both call considerable damage to hives that are in weak condition.
• Are a serious problem in warm weather and dark conditions.
• They can do a lot of damage in a very short period of time. Larva tunnel through comb eating bee pupal cocoons and destroying wax, leaving webbing and feces.

Minor Damage or Major Damage is just a function of time.��In nature, they clean out failed hives, getting the cavity ready for the next swarm to move in.

Wax�Moth�Larva

Plastic foundation makes no difference.

Treatment:

• Wax moths attack weak hives. Strong hives will keep them under control by removing eggs and larvae.
• Wax moths do not like light. Exposing equipment to light will deter moths.
• Store empty frames in cold storage, or at least freeze all empty frames to kill eggs initially.
• Closing up equipment tightly and fumigating with "Para-moth" (Para-Dichlorobenzene crystals).
• Using biological control such as Bacillus thuringiensis (BT-401, Certan, Xentari).

Small Hive Beetles

Aethina tumida

• The SHB is first reported in the United States but is becoming a global problem.
• Clearly visible: The small beetle is black/dark brown and can be found moving rapidly inside the hive when exposed to sunlight.
• The larvae do the principal damage by leaving a slime trail within the hive. They make a complete mess of a hive with total loss of comb in the frames and total loss of honey crop through fecal contamination and fermentation.
• SHB prefers weak hives, especially queenless hives, but can still overwhelm a strong hive.

Small Hive Beetles

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SHB Treatment

Mechanical:

• Mash with hive tool
• Suck out with vacuum
• Trap with various traps

Chemical:

• GardStar soil drench (permethrin). SHB pupate in soil beneath hives. Highly toxic to bees; follow directions carefully.
• Checkmite+ (coumaphos)

SHB Traps

Anything else?

• Ants, Skunks, Raccoons, Mice, Bears...