EN
These investigations aimed to evaluate the influence of acaricides used in Bulgaria (based on amitraz, cumaphos and fluvalinate) on some factors of the non-specific bee immunity in the appearance of chalkbrood. It was found that the changes of protein concentration and lysozyme amount in the haemolymph and the pH of bee intestine depend on different active substances of the drugs. Field trials canied out on 526 colonies revealed that the lower resistance of bees infected with Varroa jacobsoni was a cause of the appearance of chalkbrood. This resistance was additionally decreased by using the anti-Varroa mite product “Perizin”.