Mortalities induced by entomopathogenic fungus

Abstract

The objective of this study was to compare the infectivity of Metarhizium anisopliae at a concentration of 1 × 108 conidia/ml to developmental stages of Amblyomma variegatum, Rhipicephalus appendiculatus and Rhipicephalus evertsi evertsi in oil and water formulations. The fungus, M. anisopliae, induced 50-100% mortalities in all developmental stages of the tick species tested. R. e. evertsi was more susceptible to M. anisopliae than the other two tick species. However, there was no clear difference in mortality between fed and unfed instars of different tick species. Furthermore, engorged adults were more susceptible than unfed adult ticks. Oil formulated conidia induced significantly higher mortalities (P<0.05) than water formulated conidia. The results indicate that the type of conidia formulation is critical to the performance of fungi as biological control agents for ticks.