Varroa mites (Varroa destructor) are tiny, reddish-brown external parasites that primarily affect honey bee colonies.

They are considered a threat to beekeeping and honey bee populations worldwide.

Here is a quick overview of varroa mites

• Appearance and Biology: Varroa mites are visible to the naked eye and are usually about 1 to 1.5 mm in size. Their flattened body allows them to cling tightly to bees. The mites reproduce in the brood cells of honey bees, where they feed on the developing larvae and pupae.
• Impact on Bees: These mites weaken honey bees by feeding on their hemolymph (the bee equivalent of blood), transmitting various viruses, such as the deformed wing virus, which can lead to physical deformities and impaired development. Infestations can result in reduced colony strength, decreased honey production, and eventually, colony collapse if not managed effectively.
• Spread and Infestation: Originally parasitizing the Asian honey bee (Apis cerana), Varroa mites have spread to nearly all parts of the world due to the global movement of bees. They are now found in the European honey bee (Apis mellifera), which lacks the natural defenses against these parasites.
• Management and Control: Managing Varroa mites involves a combination of chemical treatments, such as miticides, and non-chemical methods, like drone brood removal and screen bottom boards. Integrated Pest Management (IPM) strategies are essential to control mite populations and minimize resistance to treatments.

The Lifecycle of Varroa Mites

The lifecycle of Varroa destructor is intricate and tailored to maximize its reproductive success while parasitizing honey bees. Here’s a detailed overview:

Lifecycle Stages

1. Phoretic Stage
   • Adult Female Mites: In this stage, adult female mites live on adult honey bees, feeding on their hemolymph (bee blood). They cling to the bees’ bodies, often hiding between the abdominal segments.
   • Duration: This stage lasts from a few days to several weeks, depending on the availability of brood and environmental conditions.
2. Reproductive Stage
   • Entering Brood Cells: Female mites enter brood cells containing 5th instar larvae just before the cells are capped with wax by worker bees.
   • Reproduction: Inside the capped cell, the mite feeds on the developing bee larva and begins to lay eggs. The first egg is usually male, followed by multiple female eggs at regular intervals (approximately every 30 hours).
3. Developmental Stages
   • Egg: The eggs hatch into immature mites.
   • Protonymph: The first stage after hatching. Protonymphs molt into deutonymphs.
   • Deutonymph: The second immature stage, which eventually molts into an adult mite.
   • Adult Mites: Newly emerged adult female mites mate with the male mite inside the brood cell.
4. Emergence
   • Emerging from the Cell: When the worker or drone bee emerges from the brood cell, the mature female mites and any new adult females leave the cell attached to the bee. Male mites do not survive outside the brood cell and die after mating.

Key Points

• Duration: The entire reproductive cycle, from egg to adult mite, takes about 10 days in worker brood and around 14 days in drone brood.
• Reproductive Output: Female mites can produce multiple offspring in a single brood cell, but the success rate varies depending on the conditions within the cell and the health of the host bee.
• Seasonal Variation: The lifecycle of Varroa mites is influenced by the seasonal brood pattern of honey bees. Mite populations often increase during the active breeding season of bees and decrease during periods when brood rearing is reduced or halted.

Lifespan of Varroa Mites

The lifespan of Varroa mites varies depending on their role and environmental conditions. Here’s a breakdown:

Female Mites

• Outside Brood Cells: Adult female mites live on adult bees, feeding on their hemolymph. They can survive for a few days to several weeks outside of brood cells, depending on temperature and humidity.
• Inside Brood Cells: When inside brood cells, female mites lay eggs and reproduce. The female mites that emerge from brood cells can live for several months, often up to 2-3 months, especially during the winter when they remain with the bees inside the hive.

Male Mites

• Reproductive Phase: Male mites have a much shorter lifespan. They are primarily involved in mating within the brood cells and typically die shortly after fertilizing the female mites. They do not survive outside the brood cells.

Factors Influencing Lifespan

• Host Availability: The presence of a suitable host (honey bees) is crucial for mite survival.
• Environmental Conditions: Temperature, humidity, and hive conditions can affect the lifespan and reproductive success of Varroa mites.

The combination of these factors influences the overall lifespan and reproductive capacity of Varroa mites, making effective management strategies essential for controlling their populations.

Brief History of Varroa Mites

Discovery and Early History

• 1904: Varroa mites were first discovered by A.C. Oudemans in Java, Indonesia, parasitizing the Asian honey bee (Apis cerana).
• 1940s: The mites spread to the European honey bee (Apis mellifera) through the movement of bee colonies between Asia and other regions.

Global Spread

• 1987: Varroa mites were detected in the United States.
• 1990s: The mites continued to spread to Europe and other parts of the world.
• 2000: DNA analysis led to the reclassification of the mites, identifying Varroa destructor as the species affecting European honey bees.

Impact and Management

• Economic Impact: Varroa mites have caused significant economic losses in the beekeeping industry due to their ability to transmit viruses and weaken bee colonies.
• Management Strategies: Beekeepers have developed various methods to manage Varroa mites, including chemical treatments, breeding mite-resistant bees, and integrated pest management (IPM) approaches3.

Ongoing Challenges

• Resistance: Varroa mites have developed resistance to some chemical treatments, making management more challenging.
• Research and Innovation: Continuous research is being conducted to find more effective ways to control Varroa mites and protect honey bee populations.

20 Ways Varroa Mites Impact the Economy

Varroa mites have a wide-ranging impact on the economy, affecting various sectors from agriculture to beekeeping.

More specifically:

1. Reduced Honey Production: Infested colonies produce less honey, leading to lower yields and revenue for beekeepers.
2. Increased Management Costs: Beekeepers spend more on treatments, monitoring, and labor to manage Varroa mites.
3. Colony Collapse: Higher mortality rates result in the loss of entire colonies, requiring beekeepers to invest in new colonies.
4. Pollination Services: Reduced bee populations lead to higher costs for renting bee colonies for crop pollination.
5. Crop Yields: Lower pollination efficiency results in reduced crop yields, affecting farmers’ income.
6. Food Prices: Decreased crop yields can lead to higher food prices for consumers.
7. Export Markets: Countries with Varroa infestations may face restrictions on exporting honey and other bee-related products.
8. Research and Development: Funding is required for developing new treatments and management strategies.
9. Insurance Costs: Beekeepers may need to purchase insurance to cover losses due to Varroa mites.
10. Labor Costs: Increased labor is needed for monitoring and applying treatments.
11. Loss of Wild Bee Populations: Wild bees are also affected, impacting ecosystems and biodiversity.
12. Environmental Impact: Chemical treatments can have negative effects on the environment and non-target species.
13. Tourism: Areas known for honey production and beekeeping may see a decline in tourism.
14. Market Competition: Beekeepers in areas with high Varroa infestations may struggle to compete with those in mite-free regions.
15. Government Spending: Governments may need to invest in research, education, and support programs for beekeepers.
16. Agricultural Diversification: Farmers may need to diversify crops or invest in alternative pollinators.
17. Economic Losses in Horticulture: Horticultural crops that rely on bee pollination may suffer economic losses.
18. Supply Chain Disruptions: Reduced honey and bee-related product supply can disrupt supply chains.
19. Consumer Awareness: Increased awareness of Varroa mites may lead to changes in consumer behavior and demand.
20. Global Trade: International trade of bees and bee products can be affected by Varroa mite regulations and restrictions.

These impacts highlight the importance of effective Varroa mite management to support the economy and ensure the sustainability of beekeeping and agriculture.

5 treatment options for managing Varroa mites

1. Preventative Strategies:
   • Mite-Resistant Bees: Breeding bees that are naturally resistant to Varroa mites.
   • Small Cell Comb: Using smaller cell sizes to disrupt the mites’ reproductive cycle.
2. Non-Chemical Strategies:
   • Brood Break: Removing brood frames to interrupt the mites’ life cycle.
   • Mite Trapping: Using traps to capture mites.
   • Screened Bottom Boards: Allowing mites to fall out of the hive.
   • Powdered Sugar Dusting: Coating bees with powdered sugar to dislodge mites.
3. Soft Chemical Strategies:
   • Oxalic Acid: A natural acid that can be used in vapor form.
   • Formic Acid: Effective in controlling mites but requires careful application.
   • Thymol: An essential oil derived from thyme.
   • Hops Beta Acids: Derived from hops, used as a natural acaricide.
4. Hard Chemical Strategies:
   • Amitraz: A synthetic chemical used in strips placed inside the hive.
   • Apistan: Contains tau-fluvalinate, effective against mites but resistance can develop.
5. Integrated Pest Management (IPM):
   • Combining multiple strategies to manage mite populations effectively while minimizing harm to bees and the environment.

Each method has advantages and limitations, and often a combination of treatments is used to achieve the best results.

It’s essential to monitor mite levels regularly and adjust management strategies accordingly.

Preventive Measure Against Varroa Mites

Preventing and managing Varroa mites is critical to maintaining healthy bee colonies. Here are several preventive measures that beekeepers can implement:

1. Mite-Resistant Bee Strains

Selective breeding for mite-resistant bee strains, such as the VSH (Varroa Sensitive Hygiene) bees, can help reduce mite infestations.

2. Genetic Diversity

Promoting genetic diversity within bee colonies can enhance the natural resistance of bees to Varroa mites and other pathogens.

3. Small Cell Comb

Using small cell combs (4.9 mm) can limit the space available for mite reproduction and reduce their population.

4. Screened Bottom Boards

Installing screened bottom boards allows mites to fall through the screen and be removed from the hive, reducing their numbers.

5. Powdered Sugar Dusting

Regularly dusting bees with powdered sugar encourages grooming behavior, which helps dislodge and remove mites from the bees.

6. Brood Interruption

Introducing a brood break by caging the queen or removing brood frames can disrupt the mite’s reproductive cycle.

7. Drone Brood Removal

Mites prefer drone broods, so beekeepers can use drone broods as a trap by periodically removing and destroying infested drone frames.

8. Biotechnical Methods

Using thymol-based treatments, which are derived from thyme oil, can help control mite populations naturally.

9. Probiotics and Bee Health

Ensuring bees have access to a diverse range of flowers and supplementing their diet with probiotics can improve bee health and resistance to mites.

10. Regular Monitoring

Regularly monitoring mite levels using methods such as sticky boards or alcohol washes helps beekeepers take timely action before infestations become severe.

11. Chemical-Free Treatments

Research is ongoing into biological control agents such as predatory mites that could help manage Varroa populations.

12. Environmental Controls

Placing hives in locations with good sunlight and ventilation can reduce humidity levels, making it less favorable for mites.

13. Mechanical Traps

Using mechanical traps within the hive to physically capture and remove mites.

14. Natural Treatments

Treatments with essential oils, such as wintergreen, eucalyptus, and tea tree oil, are being explored for their effectiveness against mites.

15. Heat Treatments

Applying controlled heat treatments to hives can kill mites without harming the bees.

16. Mineral Oils

Spraying bees with food-grade mineral oils can suffocate mites and reduce their population.

17. Varroa Gates

Installing Varroa gates at the hive entrance that bees pass through, can reduce the number of mites entering the hive.

18. Comb Rotation

Regularly rotating out an old comb and replacing it with a new wax foundation can help manage mite populations.

19. Natural Predators

Research into natural predators of Varroa mites is ongoing, looking for ways to integrate them into hive management.

20. Integrated Pest Management (IPM)

Using a combination of biological, mechanical, and chemical treatments in an IPM approach to manage mite populations effectively while minimizing harm to bees and the environment.

Countries with the Most Varroa Mite Cases

Varroa mites are widespread globally, affecting honey bee populations in many countries. Some of the countries with the most Varroa mite cases include:

1. United States: Varroa mites were first detected in the late 1980s and have since become widespread across the country.
2. New Zealand: Varroa mites are common, and beekeepers have had to adapt management strategies to cope with the infestation.
3. Australia: Although Australia has maintained a policy of eradication, recent detections have increased, particularly in regions like New South Wales.
4. Europe: Many European countries, including Germany, France, and the United Kingdom, have significant Varroa mite infestations.
5. Asia: Countries like China and Japan have long dealt with Varroa mites, originally affecting the Asian honey bee (Apis cerana) before spreading to European honey bees.

These regions have implemented various management and control strategies to mitigate the impact of Varroa mites on honey bee colonies.

Resources to Learn More About Varroa Mites

BuzzBeeHive: Varroa Mites: How to Identify, Treat, and Prevent – This comprehensive guide covers the biology, identification, symptoms, and various treatment methods for Varroa mites.

Honey Bee Health Coalition: Tools for Varroa Management – A detailed guide on effective Varroa sampling and control, including chemical and non-chemical methods.

National Varroa Mite Management Program: Online Training – Offers online and face-to-face training on Varroa basics, life cycle, symptoms, detection, spread, monitoring, and integrated pest management.