Sensitivity of Ixodes ricinus (L., 1758) and Dermacentor reticulatus (Fabr., 1794) ticks to Bacillus thuringiensis isolates: preliminary study

Bacillus thuringiensis is a highly specific entomopathogenic microorganism. Although defined as having properties which work against insects, its role in the control of tick populations is still insufficiently known. In our bioassay, four environmental strains of B. thuringiensis, along with one commercially available product (Vectobac), have been used against ticks. Vectobac turned out to be ineffective in the biocontrol of ticks; however, two of environmental B. thuringiensis strains proved to be efficient against both Ixodes ricinus and Dermacentor reticulatus. In those cases, the mortality rate for ticks was assessed as being up to 80%, and LC50 ranged between 9.1 × 106 and 1.3 × 1015 (cfu/ml). Dermacentor reticulatus males were the most sensitive to bacteria. The similarity between the most and least efficient B. thuringiensis strains in enzymatic profiles—including lipases, phosphatases, proteases, and chitinases—may indicate a limited role of detected enzymes in the pathogenicity profile of bacterial strains against ticks.