Solid fermentation of Metarhizium robertsii: substrate and culture conditions on conidia production and the biological efficacy

Abstract

The implementation of entomopathogenic fungal conidia represents an alternative with advantages compared to chemical insecticides. Their production can be carried out on inexpensive substrates. The culture conditions, including substrates, temperature, moisture, and aeration rate for the production of Mr Xoch8.1 conidia in solid culture were examined; the research was conducted in Ecatepec de Morelos, State of Mexico, in 2022. An analysis of the quality of the conidia was carried out at the laboratory level, considering germination, viability, and infectivity. A conidiation profile was made during 11 days of culture of the Mr Xoch8.1 strain in solid fermentation. The highest production of conidia was observed at eight days. Production was evaluated on different substrates, with the production with white rice standing out. The incubation temperature at 28 °C was the most appropriate. The absence of forced aeration generated the highest production. The initial moisture of 60% led to a high production of conidia. The germination and viability of the conidia were 93% and 57%, respectively. In terms of infectivity, a mortality of 60% was achieved in mealworm. The production of Mr Xoch8.1 conidia in solid fermentation is a sustainable alternative through the use of inexpensive substrates and controlled conditions, such as a temperature of 28 °C, moisture of 60%, and absence of forced aeration. These conditions allow a high production of conidia with good germination, viability, and infectivity, demonstrating their potential as a biological control agent.