Due to its role in the transmission of Candidatus Liberibacter asiaticus, a pathogen associated with huanglongbing, a catastrophic disease of citrus in the world, Diaphorina citri Kuwayama (Hemiptera: Liviidae) has become a very dangerous invasive pest. To contribute to increasing alternatives for its management, we evaluated against D. citri adults the pathogenicity of conidia and blastospores of 8 Mexican strains of the entomopathogenic fungus Hirsutella citriformis Speare (Hypocreales: Ophiocordycipitaceae). Furthermore, we conducted tests with non-target insects that included the predators Hippodamia convergens Guérin-Méneville (Coleoptera: Coccinellidae) and Chrysoperla rufilabris (Burmeister) (Neuroptera: Chrysopidae). Experiments in the laboratory included the application of the fungus by contact and through liquid sprays. Strains were collected from citrus areas of Mexico. They were grown in PDAY media and applied at 1 × 106 conidia per mL. All bioassays were conducted under controlled co... Resumen Debido a su función en la transmisión de Candidatus Liberibacter asiaticus, un patógeno asociado al Huanglongbing, una enfermedad catastrófica de los cítricos en el mundo, Diaphorina citri Kuwayama (Hemiptera: Liividae) se ha convertido en una plaga invasiva muy peligrosa. Para contribuir a incrementar las alternativas para su manejo, evaluamos la patogenicidad de conidias y blastosporas de 8 cepas mexicanas del hongo entomopatógeno Hirsutella citriformis Speare (Hypocreales: Ophiocordycipitaceae) contra adultos de D. citri; además realizamos pruebas contra insectos no blanco, los depredadores Hippodamia convergens Guérin-Méneville (Coleoptera: Coccinellidae) y Chrysoperla rufilabris (Burmeister) (Neuroptera: Chrysopidae). Los experimentos en laboratorio incluyeron aplicación del hongo por contacto y mediante aspersiones. Las cepas fueron colectadas en diferentes áreas citrícolas de México, cultivadas en medio PDAY y asperjadas a 1 × 106 conidia/mL; todos los bioensayos fueron conducidos bajo cond...

Some actinobacterial species have been reported to improve plant growth due to their roles as biostimulants and biological control agents. In this study, the effect of actinobacterial isolate 27, obtained from the rhizospheric soil of melon plants and identified as Streptomyces calvus, was evaluated on the growth of Arabidopsis thaliana and tomato plants. In Arabidopsis, in vitro assays showed that after seven days of interaction, isolate 27 increased fresh weight by 1.4-, 1.5-, and 2.3-fold and lateral root number by 1.7-, 1.3-, and 2.5-fold under physical contact and split-plate systems (MS and ISP2 media), respectively, compared with non-inoculated plants. An increased β-glucuronidase (GUS, encoded by the uidA gene) signal was observed in primary and lateral roots of the Arabidopsis DR5::uidA reporter line during both interaction types, suggesting the activation of auxin-responsive pathways. In addition, isolate 27 rescued the rhd6 (root hair defective 6) mutant phenotype, restoring root hair formation. Gas chromatography-mass spectrometry (GC-MS) analysis revealed that isolate 27 emitted volatile organic compounds (VOCs), including an alcohol and several sesquiterpenes, and that this profile changed during interaction with Arabidopsis plantlets. In soil-based pot assays, inoculation with isolate 27 significantly enhanced the development of Arabidopsis plants after 23 days, both when applied alone and in co-inoculation with Trichoderma atroviride. Furthermore, isolate 27 stimulated tomato plant growth, leading to significant increases in fresh and dry biomass, as well as shoot and root lengths after 28 days. Overall, these results demonstrate that S. calvus isolate 27 promotes plant growth and development through the production of bioactive compounds that modulate plant growth pathways, including hormonal responses, highlighting its potential as a bioinoculant for sustainable and productive agricultural systems.