Experimental infections of the tick Rhipicephalus appendiculatus with entomopathogenic fungi, Beauveria bassiana and Metarhizium anisopliae, and natural infections of some ticks with bacteria and fungi

Abstract

Two strains of the entomogenous fungus, Beauveria bassiana, were found to be pathogenic to all stages of the tick Rhipicephalus appendiculatus in the laboratory. A mortality of up to 73 percent of unfed adults was recorded, while the entomogenous fungus Metarhizium anisopliae was found to be only slightly pathogenic killing only 35 percent of unfed adults. Unfed ticks immersed in suspensions of B. bassiana spores engorged normally on rabbits, but 74 percent of them failed to lay eggs. The fecundity of those which laid eggs was reduced to 10 percent compared to controls in natural infections. 9.77 percent and 1.7 percent of 423 adults, engorged R. appendiculatus females which had stayed in grass plot for 8 days died due to bacterial and fungal infections respectively. The isolated fungi were from the genera Aspergillus, Fusarium and Mucor but their species were not determined. Large number of a laboratory colony of Boophilus decoloratus were found to be infected with Staphylococcus aureus and Escherichia coli. The possibility of using pathogens for control of ticks is discussed.