A group of beneficial bacteria that colonize around the root surface of plants, known as plant-growth promoting rhizobacteria (PGPR), are emerging as a potential approach for managing plant stressors in agricultural settings. PGPR are known for enhancing plant growth and an induced systemic resistance (ISR) to a range of biotic stressors. However, while much is known about PGPR-mediate pathogen resistance in the plant, less is known about their role in plant resistance to insects. Therefore, a study was conducted to characterize the effect of the PGPR Bacillus velezensis GA1 on tomato resistance to two chewing insect pests, Spodoptera exigua and S. frugiperda, which are found to have suitable host acceptance and unsuitable host acceptance to tomato, respectively. Through a series of life table analyses and feeding assays, it was found that S. frugiperda was susceptible to PGPR-treated tomato, having increased developmental time in the larval stage as well as reduced feeding activity. However, S. exigua were not significantly impacted by the PGPR treatment. These results support previous work that that PGPR-mediated resistance to insects can be species-specific, rather than broad-spectrum, even within the same feeding guild.
