The conidia of the entomopathogenic fungus Metarhizium anisopliae were formulated in an invert emulsion (water-in-oil formulation) with a coconut/soybean oil preparation providing the most stable emulsion layer (93%) and lowest viscosity (27 cps). The fungal conidia remained viable in the formulation for 30.8 months with a 50% reduction (half-life) in conidial viability after 4.6 months at 20±1°C. In comparison, dry non-formulated conidia held under the same conditions were non-viable after 2 months, with a half-life of 0.5 month. The invert emulsion remained stable throughout the study. Under laboratory conditions, the fungus, at a concentration of 5×10⁶ conidia/ml, killed nymphs of the tobacco whitefly, Bemisia tabaci, within 3 days of treatment, with fungal outgrowth and sporulation observed on the cadavers within 4–5 days. Whitefly mortality ranged from 66.7 to 100% under laboratory conditions. When tested under field conditions, whitefly mortality ranged from 30.0% to 92.2% on eggplants. The fungus, at a concentration of 5×10⁶ conidia/ml also killed nymphs and adults of the red spidermite, Tetranychus cinnabarinus, within 3–4 days of treatment under laboratory conditions, with fungal outgrowth and sporulation observed on the cadavers within 5 days. Spidermite mortality ranged from 58.3% to 93.3% under laboratory conditions. When tested in the field, spidermite mortality ranged from 25.9% to 90.6% on eggplants. For both pest species, significantly higher levels of mortality were obtained when formulated conidia were compared to the non-formulated conidia or the control treatments, whether tested under laboratory or field conditions. When the formulation blank was applied as control treatment, mortality was not significantly different from the distilled water-treated controls. The fungus thus shows great potential for management of both pests and activity appears to be enhanced when applied in a coconut/soybean oil formulation.

Title

Crop Protection

Publisher

Elsevier

Publisher Country

United States of America

Publication Type

Prtinted only

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