Varroa destructor, How bad could that bee? Philip Moore Research Associate The University of Tennessee

Transcription

1 Varroa destructor, How bad could that bee? Philip Moore Research Associate The University of Tennessee

2 bees.tennessee.edu

3 extension.org/bee_health You Tube: BeeHealth Facebook: Bee extension.org

4 Integrated Pest Management (IPM) Understand the pest s lifecycle, impact on host, signs, and symptoms Monitor pest populations regularly and use a treatment threshold Sample at least every spring and late summer Use cultural control to minimize the need for treatment Use resistant varieties: Russian or Varroa Sensitive Hygienic (VSH) Maintain healthy, well feed colonies and minimize other stressors Use mechanical controls to kill pest without chemicals Drone comb removal Screen bottom board Use chemical control to keep pest below threshold Avoid pest resistance development Use complete treatment dose Monitor pest population after treatment, potentially retreat to kill remaining population Rotate treatment method

5 Understand the pest s lifecycle, the signs and the symptoms Signs = direct observation of the pest Symptoms= indirect indicators of the pest s presence

6 What are Varroa? Varroa destructor Ubiquitous Blood Suckers Disease Spreader Nutritional Stressor #1 Colony Killer

7 Varroa Life Cycle Phoretic Stage Adult Parasitism 5-11 days, up to 5-6 months Natural Drop < 20% of total Screen Bottom Board Reproductive Stage Brood Parasitism Feed on pre-pupa after cell capping Lay male and female eggs Mature female mates with male Emerge with adult bee

8 Impact of Varroa Parasitism on Bee Health Contributes to colony stress and susceptibility to other ailments Reduced body weight of adult bees and brood Even in non-parasitized adults from infested colonies compared to noninfested Weight is a key factor in the bees ability to perform colony tasks, especially flying Underweight bees tend to become forages earlier in life and tend to drift off site Reduced Nutrition Reduced protein and body sugar of parasitized bees Increased energy demand May reduce immune system response (AMPs)

9 Varroa Vectored Viruses Viruses: DNA or RNA in a protein coat, which use host cell machinery to reproduce, until cell ruptures and virus spreads Many Transmission Routes: Can be found in nectar, pollen, jelly, eggs, sperm, queens Most deadly when injected by Varroa directly into hemolymph Typically infect larval or pupa stage Symptoms are most obvious in adults Symptoms can be Acute (obvious) or Covert (concealed)

10 How Common are Viruses? Figure 5: 2013 USDA-APHIS National Honey Bee Pests and Diseases Survey, Virus Prevalence Results (Virus abbreviations: BQCV=Black queen cell virus; DWV= Deformed wing virus; LSV2= Lake Sinai virus 2; ABPV= Acute bee paralysis virus; KBV= Kashmir bee virus; IAPV= Israel acute paralysis virus; CBPV= Chronic bee paralysis virus; SBPV= Slow bee paralysis virus)

11 Deformed Wing Virus (DWV) Acute infections caused by Varroa Deformed wings Shortened abdomen Early death (prior to emergence or within 3 day) Covert infections spread through food and from queen to egg May infect 100% of colony, even without showing symptoms May affect aggression and learning behavior Strongly associated with winter mortality, irrespective of Varroa

12 Acute Bee Paralysis Virus Complex Acute Bee Paralysis Virus (ABPV) Similar to CBPV, but more rapid mortality Directly linked to Varroa (50-90% transmission rate) Pupae die before emerging, symptoms less obvious Kashmir Bee Virus (KBV) Spread primarily by Varroa Similar to ABPV, but more virulent Kills all forms of bee lifecycle No known symptoms Israeli Acute Paralysis Virus (IAPV) Spread primarily by Varroa Similar to ABPV and CBPV Symptoms include: trembling wings darkened hairless abdomens and thoraxes Associated with CCD Slow Bee Paralysis Virus (SBPV) Similar to ABPV, but less virulent Induces paralysis symptoms after 12 days, only on fore legs Spread by Varroa Not yet found in the U.S.

13 Acute Bee Paralysis Virus Complex

14 Monitor pest populations regularly and use a treatment threshold 1. Threshold = the level of pest where the financial loss from damage exceeds the cost of the treatment 2. Threshold = your tolerance level, based on your operation and experience

15 How do I know there s a problem? Check your brood pattern! Collect a sample and submit to USDA Count Varroa with sticky board or sugar roll Pay attention to bee behavior, colony population changes, food storage, brood smell Watch out for overt symptoms

16 Submit to USDA Indicate what you would like to sample: Varroa Nosema Foulbrood Chalkbrood Tracheal Mites NO Viruses Will receive results via in a few weeks

17 rg/pages/22279/powdersugar-roll-for-varroasampling#.va-zpsdrgkl

18 Sticky Board How to Make your own Materials: Corrugated plastic sheet (political signage) Tree TangleFoot Mineral Spirits Paint Stirrer 1 Gallon Paint Bucket &Tray 4 Paint Brush or Mini- Roller Plastic Wrap $3-4 from most bee supply companies

19 Beltsville Screen Tennessee Trap Guy's Screen Insert Brushy Mountain $15 Tally hand Counter Amazon $3

20 Treatment Thresholds and Sensitivity Sticky Board: Samples whole colony Threshold depends on colony population About mites per day for small to medium size colony Up to 150 mites per day for large strong colony Sugar Roll: Samples ~1% of adult bees Threshold is about 5 mites per 300 bees Keep Mite Population Below 1% of Adult Bee Population

21 Use cultural and mechanical controls to minimize the need for treatment Cultural control = preventative, minimize the damage of pests or make environment less suitable for pest Mechanical control = any non-chemical method of killing a pest

22 Cultural and Mechanical Controls Cultural Controls Use resistant varieties: Russian Varroa Sensitive Hygienic (VSH) Minnesota Hygienic Mechanical Control Drone comb removal Screen bottom board Powdered sugar Maintain healthy, well feed colonies Minimize other stressors

23 Use chemical control to keep pest below threshold and avoid pest resistance development Use complete treatment dose Monitor pest population after treatment, potentially retreat to kill remaining population Rotate treatment method

24 Varroa Treatment Options Not recommended: Apistan (Fluvalinate) CheckMite+ (Coumaphos) Mite resistance is common Readily contaminates honey and wax Deadly interactions with other chemicals Recommended: Apiguard (Thymol) Api Life Var (Thymol, etc) Mite Away Quick Strips (Formic Acid) Apivar (Amitraz) Hopguard II (Hop Beta-Acid) NEW Option Now Approved by EPA: Oxalic Acid Used to treat broodless colonies (packages, swarms, overwintering bees)

25 Comparison of Varroa Treatment Options Trade Name Active Ingredient Treatment Period Temperature Range Cost/Treatment Honey Supers Mite Away Quick Strips Formic Acid 7 days F $ 5.00 on 95% Hop Guard II Reported Efficacy Hop Beta Acids 30 days none $ 3.67 on % Apivar Amitraz 42 days none $ 3.60 off < 99% Apiguard Thymol twice 14 days each F $ 3.40 off % Api Life Var Thymol, etc. thrice 7 days each F $ 4.80 off < 95%

26 Percent Colony Loss by Varroa Treatment A comparison of average winter colony mortality among beekeepers who reportedly applied different known Varroa control products, at least once, to a majority of their colonies between April and March of the following year. Known Varroa control products include ApiGuard, ApiLife Var, Amitraz, Coumaphos (i.e. CheckMite), Fenpyroximate (Hivastan), Fluvalinate (i.e. Apistan), Formic Acid (i.e. Mite Away II) Sucrocide, and Oxalic Acid.

27 How to Apply Varroa Treatments Check weather conditions and colony strength before applying Dose depends on colony population estimates All treatments will disrupt brood production, especially with new queens Close screen bottom board, open entrance (remove reducer) Usually need to remove honey supers Usually treat all colonies in an apiary Wear proper protective equipment; Always wear Chemical Gloves, sometimes a Chemical Respirator or Eye Protection Follow the Label It s the Law!

28 How to Apply Varroa Treatments Gel Formulations: Apiguard, MAQS Apply recommended dose to top bars in the middle of the brood nest Impregnated Strips: Hop Guard, Apivar Insert recommended dose in-between frames of brood nest Wafers: Api Life Var Break wafer into 4 pieces, place on top bars in the corners of brood nest

29 Summary 1. Varroa mites are currently the greatest pest threat to honey bees and their colonies, and infested colonies will probably perish if action is not taken to control the mites. 2. Monitoring hives for mite levels enables beekeepers to determine whether treatment is necessary 3. The exclusive and continual use of one chemical product is more likely to result in resistance by the pest. Several different products should be used on a rotating basis. 4. It is illegal to apply any unapproved chemical in a hive or to apply approved chemicals outside of label directions.