The ideal frequency range to harm the varroa mites is between 14.000 and 15.000 Hz with 90 decibel.
In this range varroa-mites are extremely disturbed in food consumption, with the result that adult mites die within 10-20 days. The acoustic noise works in the brood, too. The juveniles (joung mites) are dying in the breeding cell within one day. Adult mites in the brood are violated extremely and reproduction is stopped at once.
The chart illustrates the treatment of 5 bee-colonys, beginning at 04/10/2016. Daily 12-18 dead mites bevore starting the treatment. During treatment we had between 87 and 109 dead mites daily within 20 days. After that there were nearly no mites at all...
The next picture shows a treatment, now running in Berlin.
Comparing the mite drop before and during the treatment, the effect becomes clear.
(Treatment is on a small hive with an estimated Varroa- population of 90 mites. After 25 days OS was used to determine how many mites possibly survived)
Here is the result in detail:
74 dropped mites during the Varroa-Killer-Sound Treatment.
10 mites after OS-treatment.
Calculated max. 1 mite is still alive inside the hive...
Efficiency of the Varroa-Killer-Sound treatment in this case is about 87%