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 locusts in sub-Saharan Africa are produced in a purpose-built facility at the International Institute for Tropical Agriculture in Benin using a standard two-stage mass-production system. The yields average 31.1 g of dry conidia powder/kg of vice substrate, the production capacity is 300-356 kg of conidial year and the production costs are estimated at US$21/100 g (the recommended 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 are 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 variation. The handling rime, a principal limiting factor, could be reduced by increasing the substrate quantity/unit of production. An awareness of these factors presents the opportunity to fine tune production. although the options for increasing or improving production efficiency ave limited within the constraints of the system.