Optimization Of Metarhizium Anisopliae (Metgra4 Strain) Mass Production: A Bio Control Agent Against Red Palm Weevil, Rhynchophorus Ferrugineus

Abstract

The Red Palm Weevil (RPW), Rhynchophorus ferrugineus is one of the serious insect pests for major cultivated crops worldwide. The use of bio control agent such as entomopathogenic fungi is highly recommended as it is a host specific, environmental friendly and cost effective. A strain of Metarhizium anisopliae namely MET-GRA4 was isolated from Terengganu soil has the potential to be commercialized as bio-pesticide against RPW. Thus, study was conducted to screen and optimize the mass production of M. anisopliae using One Factor A Time (OFAT) and Response Surface Methodology (RSM); Central Composite Design (CCD) model. The OFAT and RSM models used to investigate the interaction of incubation time, water amount and additional supplement. OFAT model factors first screening showed that 15 ml of water, 4 weeks of incubation time yielded 1.01 g of spores. The second screening, yeast yielded 1.367 g higher than peptone, 0.982 g. The CCD models optimization found the optimum conditions to mass produce METGRA4

was at 4 weeks of incubation, yeast 2.5% - 3% and 15 ml water content, yielded 1.39 g with 77.14% to 86.43% spore viability. Then, the bioassay of adult RPW was tested to determine the pathogenicity of mass produced MET-GRA4 spore. The harvested mass produced spores were infected on adult RPW for 21 day with same spore concentration 5 x 10 8 conidia/ml but different viability. The LT50 of 80-99% viable spores recorded at 8.6 days with 92% of mycosis effect, while the lowest spore viability 30-49% took 21.37 days with 16.6% of mycosis effect.