Varroa Treatment Efficacy

The treatment efficacy of synthetic varroa treatments is reported to be generally above 98% which makes them the most efficient and effective method to manage varroa in New Zealand. These efficacies have been demonstrated in the multiple studies that are required for registration.

However, it is important to remember there are a significant number of variables that can, and do, have an impact on the achieved treatment efficacy. Understanding and addressing these factors go a long way to ensuring effective control of varroa in your hives

Factors Affecting Efficacy

  1. Storage of the treatment – all varroa treatments should be stored according to the manufacturer’s directions. For the majority of treatments, high temperatures for extended periods of time can degrade the active ingredients in the products. Treatments should never be stored in direct sunlight or left in closed vehicles. Read the label for direction on storage.

  2. Re-Infestation – With very high hive stocking rates in parts of New Zealand, many areas now contain apiaries owned by different beekeepers that are close together and treated for varroa at different times which can result in hives being reinvaded once strips are removed. In one study it was reported that 65 mites were carried into a hive per day from surrounding hives, meaning post-treatment hives can be quickly overrun but varroa. When this was particularly bad in the early days of varroa in New Zealand, many hives had to be treated twice in the Autumn.

  3. Brood nest location and hive activity – Synthetic treatments rely on bees contacting the strips and spread the treatment throughout the hive. It is very important that strips are placed in the brood nest to ensure emerging bees carrying varroa come in contact with the strips, increasing the effectiveness of the treatment.

  4. Hive condition – hives that have been poorly managed or are in bad condition at the end of the season will often exhibit poor treatment efficacies. This is a result of the reduced activity within the hive and a reduction in bee contact with the strips. A reduction in the spread of the active ingredient allows varroa to multiply unchecked in parts of the hive.

  5. Mite levels – varroa treatments are not a silver bullet to control varroa. If mite levels are significantly elevated at the end of a season, have or are approaching Parasitic Mite Syndrome, the hives may already be severely damaged and not survive despite being treated. This issue is amplified when combined with low activity within the hive and significant levels of brood.

What can I do to maximise my treatment effectiveness?

  1. Hive strength – ensure that mite levels don’t reach levels that threaten the health of the hive.

  2. Coordinate treatments with local beekeepers. Starting and finishing your treatments on the same days as your neighbours will help to reduce reinfestation.

  3. Treat per the manufacturer’s instructions. The registration of synthetics is based on data collected under particular conditions and applications. To have certainty of high knockdown, it is very important to read and follow the application instructions.

  4. Store product safely, cool, and out of the sun.

  5. Mite level monitoring. With high levels of re-infestation, mite monitoring is very important to ensure that further treatments can be administered if required.

  6. Ensure the rotation of chemical families in your applications to reduce the likelihood of resistance to the active ingredients. Apitraz for example should be alternated with treatments of Bayvarol.

  7. Some beekeepers are using a third treatment in a 12-month period to ensure that mite levels remain low throughout the year. Formic Pro is a good option for this third treatment.

Want to know more about varroa control? Talk to the team at Ecrotek now.