Laboratory evaluation of virulence of Chinese Beauveria bassiana and Metarhizium anisopliae isolates to engorged female Rhipicephalus (Boophilus) microplus ticks

Abstract

Rhipicephalus (Boophilus) microplus, an important ectoparasite that can transmit Babesia and Anaplasma, has caused inestimable economic losses around the world. Traditionally, acaricides are used for the control of ticks. However, drawbacks of chemical control, such as resistance, environmental pollution, and traces in food promote alternative strategies to pesticides. Microbial control is one option to reduce tick populations. In this study, we investigated the pathogenicity of thirteen Beauveria bassiana isolates and seven Metarhizium anisopliae isolates to the engorged female R. (B.) microplus ticks using different conidial concentrations of 107, 108 and 109conidiamL–1. Fourteen days after treatment, three B. bassiana isolates (B.bAT01, B.bAT03, B.bAT13) and one M. anisopliae isolate (M.aAT04) resulted in 100% mortality of engorged female ticks with conidial concentrations of 108 and 109conidiamL–1. Isolates of B.bAT01, B.bAT03, B.bAT13 and M.aAT04 at all conidial concentrations could reduce the reproductive efficiency index (REI) of R. (B.) microplus ticks.