The native Olla v-nigrum (Mulsant) and the exotic Harmonia axyridis (Pallas) are the predominant coccinellids found in pecan orchards in the Southeastern U.S. Adult O. v-nigrum in pecan orchards are commonly found infected with Beauveria bassiana, especially when overwintering under pecan bark. We have never observed such infection in adult H. axyridis. Three B. bassiana isolates were obtained from field-collected O. v-nigrum and a fourth from a commercially-available formulation. Toxicity of conidia from these B. bassiana isolates was tested against lab-reared O. v-nigrum adults at concentrations of 104 to 108 conidia/ml for 8 days to establish an LC50. Subsequent tests against both O. v-nigrum and H. axyridis showed that mortality of O. v-nigrum was always higher than H. axyridis mortality, especially for the isolates obtained from O. v-nigrum.
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