Arbuscular mycorrhizal fungus and Pseudomonas bacteria affect tomato response to Tuta absoluta (Lepidoptera: Gelechiidae) herbivory

Tuta absoluta (Lepidoptera: Gelechiidae) is one of the most significant invasive and destructive pests worldwide, causing serious economic losses to the tomato industry. Rhizosphere microorganism, such as arbuscular mycorrhizal fungi (AMF) and Pseudomonas bacteria, can interact with plants individually or collectively to improve plant growth and resistance to pests and disease. However, the effects of AMF, Pseudomonas, and their interactions on plant responses to insect herbivores remain unclear. A pot experiment was conducted to investigate the effects of single/dual inoculation with AMF (Funneliformis mosseae, M) and Pseudomonas putida (P) on the growth and defense of tomato variety Dafen (Solanum lycopersicum L.) in response to infestation by T. absoluta, as well as the growth, development, and enzyme activity of insect. The results showed that M, P, and MP promoted tomato growth by increasing nutrient concentrations, with the growth-promoting effect of dual-inoculation significantly surpassing that of single inoculation. M, P, and MP still improved tomato growth in T. absoluta infestation, with biomass increases of 57.34%, 54.46%, and 255.49%. M, P, and MP significantly increased the defense ability of tomato, with jasmonic acid concentrations increasing by 42.15%, 60.87% and 90.02%, and phenylalanine ammonia-lyase activity increasing by 47.40%, 47.68%, and 59.97%. The inoculation treatments inhibited the growth and development of T. absoluta, reduced its feeding, prolonged its growth and development, decreased egg weight, and increased the activity of protective and detoxifying enzymes. Overall, our results indicated that AMF and bacteria can stimulate each other, positively influence tomato growth and enhance resistance to T. absoluta. These findings indicate the feasibility of AMF and bacteria in combinations as potential biocontrol agents for the management of T. absoluta.