Production ofMetarhizium anisopliaespores using nutrient‐impregnated membranes and its economic analysis

Abstract

Metarhizium anisopliae spores were produced on nutrient‐impregnated membranes (NIMs). The NIM system involved wetting the membrane with a spore and nutrient suspension, followed by harvesting the spores produced after incubation. The cost efficiency of spore production was assessed for a range of nutrient sources and membrane types. Skim milk powder (20 g l‐1) was found to be the most cost‐effective nutrient source of the nine nutrients examined. Yield was 5.7 × 106 spores/cm2 after 28 days incubation on a paper membrane. Supplementation of the skim milk with either sucrose (2 g l‐1) or dextrose + KNO3 maximized yield. Superwipe, an absorbent fibrous material, was the most efficient of 16 membranes tested which ranged from fibreglass mesh to paper and cloth. A series of small pilot plants were built, but the cost efficiency of spore production decreased as the size of the membrane increased from 24 × 24 cm to 270 × 15 cm and up to 100 × 80 cm. Yield on the two smaller pilot plants was over 107spores/cm2, ...