This protocol aims to determine the growth factor of the Varroa mite population in spring. Ultimate goal is to select queens that show a reduced growth of Varroa.
Preparation of the board
- Make sure the board is clean, so without wax particles, dead bees, pollen clumps, etc.
- Put a sheet of white paper on the board making sure that at least 90-95% of the surface of the board is covered. The space should be inaccessible to bees. The best solution would be plastic boards, which can easily be cleaned and reused.
- You may want to cover the margins of the paper with petroleum jelly. This keeps ants and earwigs from intervening with the monitoring process.
Mite drop is monitored is estimated in the months of February, March and April over a continuous period of minimally 90 days by counting the number of fallen brown adult mites, either dead or still alive. We recommend counting every three to four days in order to avoid too much clogging of the board with debris. After counting the mites clean the board and reinsert it under the hive.
Modeling Varroa population growth
Insight in the growth factor of Varroa mites in a colony is at the basis of selection of queens and drones in breeding programmes since this growth factor is a good indication of the Varroa tolerance of a colony. Colonies with low growth factors are capable of keeping a Varroa population in check in a natural manner without beekeepers’ interventions. Hence no Varroa control is necessary.
DDB has developed a mathematical model to describe the development of the Varroa population based on the mite counts on the board.
The calculated growth factors are compared to three theoretical curves: linear (a straight line between two points), logistic (S-shaped curve) and exponential.