Selection of Beauveria bassiana (Bals.) Vuill. and Metarhizium anisopliae (Metsch.) Sorok. for the control of the mite Mononychellus tanajoa (Bondar)

Abstract

The green mite, Mononychellus tanajoa (Bondar) (Acari: Tetranychidae), is considered to be one of the key pests in cassava, Manihot esculenta Crants, leading to considerable field losses. In this study, ten Beauveria bassiana (Bals.) Vuill. and ten Metarhizium anisopliae (Metsch.) Sorok. isolates were evaluated with regard to their potential as biological control agents against adult M. tanajoa females. The total mortality percentage of M. tanajoa caused by B. bassiana ranged from 13.0 to 97.0%, with confirmed mortality rates extending from 9.0 to 91.0% and LT50 varying from 4.2 to 17.0 days. The M. anisopliae isolates showed total mortality percentages ranging from 12.0 to 45.0% with confirmed mortality rates extending from 8.0 to 45.0%, and LT50 varying from 8.6 to 19.8 days. Lethal Concentrations (LC50) of 3.93 × 10(6) conidia mL-1 and 7.44 × 10(8) conidia mL-1 were determined for B. bassiana and M. anisopliae, respectively. B. bassiana isolate 645 was the most efficient, being an alternative for use in biological control programs against the cassava green mite.