Operational and economic analysis of a West African pilotscale production plant for aerial conidia of Metarhizium spp. for use as a mycoinsecticide against locusts and grasshoppers

Aerial conidia of Metarhizium anisopliae (flavoviride) var. acridum strain IMI 330189 used for the inundative biological control of grasshoppers and l ocusts in sub-Saharan Africa are produced in a purpose-built facility at th e International Institute for Tropical Agriculture in Benin using a standar d two-stage mass-production system. The yields average 31.1 g of dry conidi a powder/kg of vice substrate, the production capacity is 300-356 kg of con idial year and the production costs are estimated at US$21/100 g (the recom mended dose for I ha). The production process parameters vary within narrow limits established during optimization, but the yield is characterized by a high level of variation over time The incubation period and temperature a re identified as keyfactors, although they account for less than 40% of the yield variation. The variation in conidial viability and contamination are correlated with several parameters, but none can adequately explain this v ariation. The handling rime, a principal limiting factor, could be reduced by increasing the substrate quantity/unit of production. An awareness of th ese factors presents the opportunity to fine tune production. although the options for increasing or improving production efficiency ave limited withi n the constraints of the system.