APPLICATION OF POWDER FORMULATION OF METARHIZIUM ANISOPLIAE TO CONTROL ORYCTES RHINOCEROS IN ROTTING OIL PALM RESIDUES UNDER LEGUMINOUS COVER CROPS

摘要

The powder formulation of Metarhizium anisopliae was applied by spraying method onto the rotting heaps of oil palm residues under the leguminous cover crops. The M. anisopliae infected all stages of Oryctes rhinoceros. At eight months after treatment (MAT), the application of product at rates of T1, 0.2 g (2.2 × 10~7 spores) and T2,0.4 g (4.4 × 10~7 spores) m~2 heap was significantly reduced (P<0.05) the L2 and L3 larvae, pre-pupae and pupae. Reduction of these four stages has reduced the overall O. rhinoceros population in T1 to 30.8 individual per sampling plot (ISP) and T2 to 41.0 ISP, significant lower (P<0.05) as compared to population in the control (132.1 ISP). The growing of cover crops delayed the impact time of the fungus, but it provided protection to the fungus from the detrimental factors, giving favourable conditions to the spores to grow and initiate infection. Therefore, at eight MAT, as the population was significantly reduced, the infection levels were increased to 33.3% in Tl and 30.4% in T2, both were significantly higher (P<0.05) as compared to control (12.9%). Then it was further increased to 52.0% (control), 67.8% (T1) and 72.9% (T2) at 12 MAT. The use of the product at both rates did not affect the non-target insects. The oil palm pollinating weevil, Elaeidobius kamerunicus was not affected as they was no difference in the population density in the treated and control plots. The population density of the stag beetle, Aegus chelifer in both treated plots was always not significant (P>0.05) with the control at all times of data recording. Although infection can occur on larvae and adults, but the percentage was low, ranging from 0% - 0.6% at five MAT and 1.7% and 2.5% at eight MAT.