To identify highly virulent Beauveria bassiana strains against Tuta absoluta and evaluate their biocontrol potential, four strains were phylogenetically characterized via ITS sequence analysis of rDNA and assessed for virulence against second-instar T. absoluta larvae. Foliar spray and root irrigation methods were used to establish B. bassiana endophytic colonization in tomato plants, with untreated plants serving as controls. A population life table was constructed to quantify the impact of colonized plants on larval development, fecundity, and key demographic parameters. Results showed variation in virulence among the four B. bassiana strains Bb1Bm, Bb2Bm, Bb1M, and BbC with Bb1Bm exhibiting the highest pathogenicity (85.00% corrected mortality at 1 × 10⁸ spores/mL). Maximum endophytic colonization in tomato leaves was observed 14 days post-inoculation with both foliar spray and root irrigation treatments. Life table analyses revealed that T. absoluta feeding on colonized plants exhibited significantly reduced survival rates, shorter adult lifespans, and lower female fecundity compared to controls. Key population parameters, including net reproductive rate (R₀), intrinsic rate of increase (r), and finite rate of increase (λ), were significantly reduced, while mean generation time (T) was significantly prolonged. These findings highlight the dual role of B. bassiana in T. absoluta management, demonstrating its potential as both a direct pathogen and an endophytic biocontrol agent capable of disrupting pest population dynamics.

Successful seed germination and plant seedling growth often require association with endophytic bacteria. Barnyard grass (Echinochloa crus-galli (L.) P. Beauv.) is a main weed during rice cultivation and has frequently been found in drought-prone fields such as cornfields in recent years. To determine whether endophytic bacteria enhance the survival chances of barnyard grass in dryland conditions, endophytic bacteria were collected from barnyard grass seeds. An endophytic bacterial strain, BC-14, was selected and confirmed as Cronobacter dublinensis based on its morphology, physiology, biochemistry, and genomic information. Moreover, C. dublinensis BC-14 secreted IAA in the Luria–Bertani broth up to 28.44 mg/L after 5 days; it could colonize the roots of barnyard grass. After the inoculation with seeds or the well-mixed planting soil, the bacterium can significantly increase the root length and plant height of barnyard grass under drought conditions. When comparing with the control group on the 28th day, it can be seen that the bacterium can significantly increase the contents of chlorophyll b (up to 7.58 times) and proline (37.21%); improve the activities of superoxide dismutase, catalase, and peroxidase (36.90%, 51.51%, and 12.09%, respectively); and reduce the content of malondialdehyde around 25.92%, which are correlated to the drought tolerance. The bacterial genomic annotation revealed that it contains growth-promoting and drought-resistant functional genes. In a word, C. dublinensis BC-14 can help barnyard grass suppress drought stress, promote plant growth, and enhance biomass accumulation, which is helpful to interpret the mechanism of weed adaptability in dry environments.