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Understanding Honeybee Diseases: Varroa Mites, AFB, EFB, and More

Learn about parasitic mites, common honeybee diseases, and effective control methods from Paul van Westendorp, a provincial apiculturist. Discover symptoms, controls, and prevention strategies for Varroa mites, AFB, EFB, Chalkbrood, and Nosema.

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Understanding Honeybee Diseases: Varroa Mites, AFB, EFB, and More

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  1. Parasitic Mites&Honeybee Diseases Paul van Westendorp Provincial Apiculturist BC Ministry of Agriculture paul.vanwestendorp@gov.bc.ca

  2. Honeybee Diseases • Varroa Mite ~ Varroa destructor • American Foulbrood ~ Paenibacillus larvae • Chalkbrood ~ Ascosphaera apis (fungus) • European Foulbrood ~ Mellisococcus pluton • Nosema ~ Nosema apis (microsporidian) • Tracheal Mite ~ Acarapis woodi • Sacbrood ~ virus (non-determined) • Viruses ~ KBV, IAPV, DWV, ABPV • Mismanagement ~ Homo sapiens destructor

  3. VARROA MITE • Not an Insect. Belongs to the Arachnids (crabs, spiders) • 8 legs (Insect; 6 legs), specialized mouthparts, flattened body • Obligate, host specific parasite ~ can’t live without the bee.

  4. Varroa mite • Female lays eggs before capping (d. 10) • F and M mate inside capped cell. M die. Only F emerge • Mite brood cycle just fits in bee brood cycle (21 – 10 = 11 days) • Preference Drone brood (23 – 11 = 12 days)

  5. Varroa Detection Methods • Apistan / Checkmite+ / Apivar strip & Sticky Board test for 24 hours • Alcohol Wash test @ One Cup of Bees (~300) • Icing Sugar Shaking Test • Natural Mite Drop Test (@Sticky Board) • Scrape Capped Drone Brood • => Monitor Regularly to Obtain FACTS. With Facts Make Management Decisions!

  6. Varroa on Drone Brood

  7. Varroa Mite Controls • Apistan (fluvalinate) / CheckMite+ (coumaphos) / Apivar (amitraz) • Contact nerve poisons, plastic strip formulations • 42 days (6 wks) treatment • Formic Acid (FA65%) • 5 x 30 ml treatment /5 days, when temperature > 12’C • 1 x 150 ml in plastic bag with slits on bottom board • ‘Mite-Gone’, ‘MAQS’ • Oxalic Acid • One application when there is little bee brood (~ fall) • Dribble method or sublimation (~ vapour) • Drone Brood Removal Method • Screened Bottom Board (>40% control).

  8. AMERICAN FOULBROOD ~ AFB • Paenibacillus larvae (formerly Bacillus larvae) • Spore-forming bacterium, spores viable for decades • Infects and kills bee brood. • Highly contagious: Spores spread by adult bees, infected hive equipment, humans and tools • Antibiotic-resistant strains ~ r-AFB • Among the most destructive bee diseases worldwide.

  9. AFB Symptoms • Perforated caps of brood cells • Brood frame has “shotgun” appearance

  10. AFB Symptoms • Examine brood frame at angle of 15 degrees • Light source (~sun) behind you • Look for scale deposit on the bottom side of brood cells • Some cells have larval tongue sticking up, but not always

  11. AFB Symptoms • Select brood cell with discolored larval remains • Insert toothpick and slowly withdraw • Slimy cell contents shows “ropiness” • Place slime and toothpick in plastic bag or wrap • Submit for microscopic examination.

  12. AFB Controls • Familiarize with symptoms, know what to look for! • Examine brood frames regularly (@ few weeks) • Remove brood frames with visible signs and burn • When several frames with symptoms, shake bees onto new frames. BURN old frames. • Adopt hygienic management practices: • Reduce equipment exchange • Replace 20% brood frames annually (~5 year replacement cycle) • Establish “hospital apiary” • Clean hive tools, coveralls, hands

  13. AFB Controls • ONLY apply Antibiotics when needed • Oxytetracycline (Oxytet), Tylosin (Tylan) • DO NOT apply drugs prophylactically • Do you take any antibiotics as a prevention to future infection? • Antibiotic applications: • Always READ label instructions before use • Don’t Overdose or Underdose: Use correct amounts! • When infection during honey season – remove honey supers, sprinkle icing sugar mix on top bars and re-install honey supers 24-48 hours later. Repeat after 3 weeks. • Infection outside honey season (in spring or fall) – apply medicated sugar syrup solution • Do Not use Antibiotic Extender Patties

  14. EUROPEAN FOULBROOD -EFB • Caused by Mellisococcus pluton, followed by Pseudobacillus alvei • Only affects larvae that die before pupal stage • Twisted appearance, discoloration of larva, NOT ropy like AFB

  15. EFB Symptoms • Irregular bee brood appearance • Caps NOT punctured like AFB-infected brood

  16. EFB Symptoms • Young larvae in the bottom of cell, discolored • Older larvae discolored and twisted

  17. EFB Controls • EFB is Stress related; apply “TLC” to your bees • Effective control with antibiotics: icing sugar or syrup

  18. CHALKBROOD • Caused by fungus, Ascosphaera apis • Only affects bee brood; mummifies larvae

  19. Chalkbrood • Mummies often on bottom board and front of entrance • Mummy can be white (asexual) or black (sexual reproduction)

  20. Chalkbrood Control • No Chemical / Drug controls available • Best control through Hygienic Impulse of bees: replace queen with new queen of hygienic stock • Reduce moisture built-up; improve aeration, raise colony off the ground, screened bottom

  21. NOSEMA • Caused by microsporidian fungus, genus Nosema • Only affects adult bees, mainly in spring: dysentery-like • Bee faeces on frame and hive surfaces

  22. Nosema Disease • Nosema apis and Nosema ceranae • Infects the epithelial cell wall of the bee gut: plugs up the cell wall, bee deprived of nutrients

  23. Nosema Diagnosis & Control • Sample of bee faeces or adult bees => send to lab • Haemocytometer; # spores/square = level of infection • When 2 m spores / bee: Apply Fumidil (fumagillin antibiotic)

  24. TRACHEAL MITE • Acarapis woodi, microscopic • “Isle of Wight” – disease 1919 • Only affects adult bees • Entire life cycle in bee trachea • Plugs up breathing tubes causing lethargic bees and reduced life-expectancy • Generally doesn’t cause colony death but may when other disease present (~Nosema)

  25. Tracheal Mite Diagnosis & Control • Microscopic examination of trachea; time consuming, • Most control through resistant bee stock • Only affects bees in spring and fall • Formic Acid / menthol crystals effective controls

  26. SACBROOD • Sacbrood caused by virus • Stress related • Symptoms similar to EFB but antibiotics not effective • Removal of larva is liquid-filled sac • Generally not persistent • Queen replacement often recommended

  27. HONEYBEE VIRUSES • Bee Viruses: • Kashmir Bee Virus ~ KBV • Acute Bee Paralysis Virus ~ ABPV • Deformed Wing Virus ~ DWV • Israel Acute Para. Virus ~ IAPV • Young bees transparent, oily, sweaty, “drunk” and crawling • No drugs/medicine available • Increase incidence attributed to Varroa and Tracheal Mites • Most common in late spring/early summer • Colony weak and bees often slow, non-active.

  28. MISMANAGEMENT • Responsible for most colony failure: • Starvation • Undetected disease, untreated disease • Controls applied too late or at wrong time • Poor winter preparation • No hygienic management practices • Lack of knowledge about life cycle of pathogen and how it relates to cycle of honeybees • Under-dosing /Over-dosing of drugs and chemicals • No brood frame replacement program • Insufficient monitoring

  29. She Needs Help & Protection

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