Beneficial fungi in the genus Trichoderma are effective control agents of noctuid moth larvae

Beneficial fungi belonging to the genus Trichoderma have well-known positive effects on plant biology, such as growth promotion, nutrients uptake efficiency, seed germination rate, influencing plant interactions with the environment and promoting plant defense against biotic and abiotic stress agents, including phytophagous insects. The fungal biocontrol agent T. afroharzianum strain T22 (T22) is capable to colonize the roots of tomato plants, eliciting an active response against insects. Here we obtained colonized tomato plants (var San Marzano nano) by coating the seeds with spores of Trichoderma afroharzianum strain T22 (T22-plant), and scored the plant-mediated effects of T22 on the moth Spodoptera littoralis (Lepidoptera: Noctuidae). Larvae fed with T22 plant leaves (T22-larvae) showed developmental delay and weight reduction associated with lower survival. Furthermore, T22-larvae showed an immunosuppressed phenotype, more susceptible, at both IV and VI instars, to sublethal doses of a biopesticide containing the entomopathogen Bacillus thuringiensis. The results obtained show a clear plant-mediated effect of T. afroharzianum on S. littoralis larvae, which could contribute to the reduction of pesticide use in agriculture by suppressing this pest or enhancing its susceptibility to biocontrol agents.