COMPARATIVE BIOLOGICAL EFFICACY OF HIRSUTELLA-THOMPSONII AND NEOSEIULUS TEKE FOR CASSAVA MITE (MONONYCHELLUS-TANAJOA) SUPPRESSION

The biological control potential of Hirsutella thompsonii Fisher (Deut eromycetes: Monilianes) was compared with that of Neoseiulus teke Prit chard and Baker (Acari: Phytoseiidae) for cassava mite, Mononychellus tanajoa (Acari: Tetranychidae), suppression. Mite infestation levels ( egg and mite motile counts and damage rating) were lower on H. thompso nii- and N. teke-treated plants than on plants sprayed with water. N. teke reduced the pest attack to a comparable level to that of H. thomp sonii. In the field, applications of aqueous suspensions of H. thompso nii at concentrations of 1.2 x 10(11) conidia/ha (CPH) and 6.0 x 10(10 ) CPH significantly lowered mite infestation on a number of recording dates. As rainfall levels increased, mite infestation and the number o f cadavers on the leaves declined. The study showed that H. thompsonii has promise for controlling M. tanajoa when the fungus is applied in harmony with other natural mortality factors.