Susceptibility of Tetranychus urticae Koch (Acari: Tetranychidae) and Aphis craccivora Koch (Homoptera: Aphididae) to Metarhizium brunneum and Trichoderma atrobrunneum Entomopathogenic Fungi

Aqueous and emulsifiable formulations of the two entomopathogenic fungi species (EPF) Metarhizium brunneum (strain ARSEF3297) and Trichoderma atrobrunneum (Ta1, PP916590), present innovative alternatives for integrated pest management (IPM). The present study investigated the behavioral responses of two-spotted spider mites (Tetranychus urticae) and cowpea aphids (Aphis craccivora) to both fungal species. T. atrobrunneum strain demonstrated superior efficacy against adult females of T. urticae and A. craccivora, achieving mortality rates of 45–82.5% and 26.67–73.33%, respectively, after five days postexposure. While the M. brunneum strain resulted in mortality rates of 32.5-77.5% for T. urticae and 23.33-70.00% for A. craccivora. Both fungal strains also exhibited toxic effects on the predatory mite Euseius scutalis, with relatively low mortality rates varying according to conidial concentration; specifically, concentrations of 1×109, 1×108,1×107,1×106,1×105 and 1×104 spores/mL resulted in mortality rates of 36.67, 30.00, 23.33, 16.67, 10.00, and 6.67%, respectively, for T. atrobrunneum. Similarly, for M. brunneum, the corresponding rates were 30.00, 23.33, 16.67, 13.33, 10, and 3.33%, respectively, after five days post-treatment. A significant reduction in the spider mite and cowpea aphid populations was observed on plants under semi-field conditions at three days post-treatment. The fungus species T. atrobrunneum showing a higher infection rate than M. brunneum. Over time, the efficacy of both isolates increased, reaching its peak at seven days post-application. This study suggests that applying M. brunneum (ARSEF3297) and T. atrobrunneum (Ta1, PP916590), in conjunction with the release of predatory mite E. scutalis, can serve as effective strategies for suppressing pest populations in agricultural systems.