Metarhizium anisopliae against Prosoestus Spp., Pests of Female Oil Palm Inflorescences: Preliminary Laboratory Tests

Abstract

Prosoestus sculptilis and Prosoestus minor (Coleoptera, Curculionidae) are female inflorescences of the oil palm pest. These insects can cause a considerable decrease (about 40%) of the setting rate. The currently proposed control method is the chemical control with the use of thiocyclam-hydrogen-oxalate, derived from the Nereistoxin. For sustainable agriculture, it is appropriate to use an integrated pest management system, including biological control. The purpose of this work is to contribute to the biological control of Prosoestus spp. by the use of Metarhizium anisopliae, entomopathogenic fungus, to improve fruit set rate of oil palm. A screening of five (05) isolates of the fungus was performed by passive and active suspensions inoculation of spores in increasing concentrations. Coded isolates CNRA-BME2 and CNRA-BME5 were most virulent for these insects with mortality rates of approximately 80% during the passive inoculation on fungic cultures. The concentration c = 10 9 spores/mL was optimal during active inoculation. Metarhizium anisopliae is therefore a potential biological control agent against Prosoestus.