Varroare resistance, the readings of my breeding people for the breeding year 2020

The bee year 2018

In this breeding year I have formed over 100 offshoots. The breeding peoples came from 2 lines, all of which have a Varroare resistance index VRI* of a maximum of 25 points.

The VRI is the ratio of the daily mite waste before demiling to the actual demiling number after demiling. The lower the VRI index, the better the varroare resistance. More on this at the end of the article.

These peoples were last on the 12th. September 2018 demilled with formic acid and winterized to 2 units (Freudenstein Mass). 10 months, from 12. September 2018 until the end of July 2019, no demiling was carried out and no drone brood was taken.

The selection of these peoples in the bee year 2019

In the context of selection, the following peoples were excluded:

✓ Peoples with late honey room release
✓ Peoples who were restless or almost aggressive
✓ Peoples who have raved
✓ Peoples who only reached the average in honey yield
✓ Peoples who weakened slightly at the end of July
✓ Peoples who achieved an index of over 32 points in the VRI exam.

In the last week of July 2019 I have the Varroaindex test with approx. 50 peoples carried out. For this purpose, these selection peoples were brought home by the outstandings, since here the daily mite counts were easier to carry out in time. 10 selection peoples were shortlisted.

The Varroare Resistance Test at the end of July 2019 – The results:

Table 1: Measurements at the end of July 2019

The evaluation of the measured values

The Ø VRI index of all peoples of this group is Ø 23.8 points. In comparison, the Ø 2017 ethnic group had a Ø VRI of 30.50 points. The lower the VRI index, the better the varroare resistance. This improved resistance by 6.7 points (23.8 in 2019 versus 30.50 in 2017) impacts the varroa mitigation number. Compared to the groups of 2017, the demilting number fell from Ø 1187 mites to Ø 719.2 mites. The daily mite waste before de-milling has also decreased from Ø 41.6 mites to Ø 29.50 mites.

The further selection

However, I would like to further select these 10 selection peoples on 5 peoples. On the table I have already ranked the 5 peoples with the best index values of 1-5. These peoples are my breeding peoples next year (2020). These 5 peoples I am subjecting to a Ø calculation. The result of the Ø reading of the breeding peoples is:

  ✓ Ø VRI Index: 20.50 points
  ✓ Ø Decay waste after 10 months: 516 mites
  ✓ Ø daily mite waste before demilding 25.4 mites

Evaluation of the measured values of the 5 breeding peoples

The VRI compared to the overall group of 2019 has improved from Ø 23.80 points to Ø 20.50 points. This improved index is having an effect. The demiling number has decreased from Ø 719.2 mites to Ø 516 mites. Ø daily mite waste before demitiling has also decreased from Ø 29.5 mites per day to 25.4 mites.

The VARROAINDEX is the ratio of the daily mite waste before demiling to the actual demiling number after demiling. With this index number, I can see even a slight improvement in varroa resistance. The comparison with the group of selection peoples of 2017 shows a very large breeding progress of the offspring. This year, in 2019, I formed about the same number of offshoots as in 2018. These will be selected as discussed in 2020.

Killed varroa mites from the bees of my breeding:

Varroa mite with bitten off legs.

Photo: Both legs of the mite are severed. In a short time, the death of the mite occurs.

The analysis of my new measured value Varroa Resistance Index

The daily mite waste before de-milling consists of mites that died of old age and those mites that were killed by the bees. This is recognizable by injuries to the mites, usually severed legs. The ratio of these two components is my measured value Varroakiller factor. If the VKF is 95% or more, this means that most mites in daily mite waste were killed by the bees before demiling. This in turn contributes to an inhibited varroa reproduction in the 10-month observation period. This resistance property works all year round, even in winter, when there is no brood. The other known resistance factors only work with existing brood. e.g.: The opening of infested brood cells, or the infertility of some varroas, these factors I have already found in my first selection peoples in 1990 and described in my two books “Beekeeping today” (1990) and in the book “VARROAESISTENT” and documented with photos. Another important resistance factor is the low attractiveness of the brood for the reproduction for the mites. This property is recognizable in demiling, most mites fall off already in the first days. All resistance factors together result in inhibited varroa reproduction over the observation period of 10 months. But again, a low demitting number does not necessarily predict good varroare resistance, a low demilbing number also arises when the people have swarmed or an optimal demiling has been performed.

Summary:

The actual demildication number divided by the Ø daily mite waste before demilding gives the measured value Varroare resistance index (VRI). The higher the varroa resistance of a people, the lower the VR index. For example, my 5 breeding peoples show an average VRI of 20.45 points, which means a very good varroa resistance. A bee colony with a VRI reading of 100 or more has no natural varroa defense. The great advantage of this resistance calculation is also that the test peoples are not exposed to unnecessary exposure to the varroa mites.