Are different strains of Beauveria bassiana equally effective against different leafcutter pest species?

Abstract: Leaf-cutter ants are a serious pest to forestry plantations and crops in Latin America. They have been traditionally controlled using chemical synthetic pesticides, which are known to have many negative effects to non-target organisms and the environment overall. Therefore, there is an urgent need for the development of alternative strategies of control among which the biological control using fungal pathogens is a promising one. In this study we evaluated 3 strains of Beauveria bassiana against 5 species of Acromyrmex leaf-cutter ant species which are considered pests. Our results showed that all strains were pathogenic, although there are some ant species that turned out to be more resistant or more susceptible. Each of the strains exhibited different efficiency for two of the ant species, but for the other three they were equally effective with high percentages of recovery (more than 80%). Considering several aspects of the hygienic behaviours of this group of ants, and the characteristics of an inundative biological control strategy, several applications of different biological agents will be needed to control them. Then, taking into account our results, our recommendation is to use the three strains in a sequential fashion in order to avoid the lack of efficiency of any of the strains against one particular ant species.