Elyes Zhioua Michael A. Benjamin Howard S. Ginsberg Richard S. Ostfeld V.L. Hornbostel 2005 <p><span>Effectiveness of the entomopathogenic fungus </span><i class="EmphasisTypeItalic ">Metarhizium anisopliae</i><span>, for controlling nymphal </span><i class="EmphasisTypeItalic ">Ixodes scapularis</i><span>, was tested in laboratory and field trials. In the laboratory, </span><i class="EmphasisTypeItalic ">M. anisopliae&nbsp;</i><span>(Metschnikoff) Sorokin strain ESC1 was moderately pathogenic, with an LC</span>₅₀<span> of 10</span>⁷<span> spores/ml and induced 70% mortality at 10</span>⁹<span> spores/ml. In a field study, however, 10</span>⁹<span> spores/ml </span><i class="EmphasisTypeItalic ">M. anisopliae</i><span> did not effectively control questing </span><i class="EmphasisTypeItalic ">I. scapularis</i><span> nymphs, and significant differences were not detected in pre- and post-treatment densities. For nymphs collected and returned to the laboratory for observation, mortality was low in treatment groups, ranging from 20 to 36%. To assess whether a chemical acaricide would synergistically enhance pathogenicity of the fungus, we challenged unfed nymphal </span><i class="EmphasisTypeItalic ">I. scapularis</i><span> with combinations of </span><i class="EmphasisTypeItalic ">M. anisopliae</i><span> and permethrin, a relatively safe pyrethroid acaricide, in two separate bioassays. Significant interactions between </span><i class="EmphasisTypeItalic ">M. anisopliae</i><span> and permethrin were not observed, supporting neither synergism nor antagonism.</span></p> application/pdf 10.1007/s10493-004-5437-z en Kluwer Academic Publishers Pathogenicity of <i>Metarhizium anisopliae</i> (Deuteromycetes) and permethrin to <i>Ixodes scapularis</i> (Acari: Ixodidae) nymphs article