The production of biological insecticides requires the identification and selection of candidate isolates of entomopathogenic fungi (EPF). The objective of this study was to characterise by virulence factors, single-spore strains of the CHE-CNRCB 303, 305, 307 strains initially identified as Isaria fumosorosea and the 224 strain of Metarhizium anisopliae to identify those with outstanding quality parameters that can serve to improve the control programme for Diaphorina citri (Hemiptera: Liviidae) in Mexico. The size of conidia and phialides was evaluated. The internal transcribed spacers established molecular identity. The selection of single-spore strains was done using radial growth (RG), the production of conidia (PC) and germination (G) rates. Principal component analysis (PCA) was used to determine the correlation between the variables and as screening criterion. Molecular and morphometric analysis confirmed that isolates 303, 305 and 307, and their singlespore strains correspond to the Isaria javanica species. The 224 strain and its single-spore strain were identified as M. anisopliae sensu lato. The statistical analysis of the RG, PC and G variables showed significant differences (P ≤ 0.05) between single-spore strains and their multi-spore strains. PCA showed a correlation between the RG and PC. The assay with Pr1 proteases associated with the surface of the conidia showed significant differences (P ≤ 0.05) for singlespore strains of I. javanica 303/2, 305/1 and 305/5 compared to the original strains. The characterisation of genetically homogeneous populations of EPF will allow us to obtain improved isolates, which are needed for the mass production of mycoinsecticides.
Resumen Diaphorina citri es el vector del Huanglongbing (HLB), enfermedad devastadora de los cítricos a escala mundial. Se realizó la búsqueda de hongos entomopatógenos (HE) como agentes potenciales de control biológico de D. citri en huertas comerciales de cítricos y plantas de mirto en zonas urbanas del estado de Colima, México. Los hongos que se encontraron asociados a la plaga fueron aislados e identificados por métodos morfológicos y moleculares. Se aislaron 30 cepas de HE del orden Hypocreales: Hirsutella citriformis, Isaria javanica, Beauveria bassiana y Simplicillium lanosoniveum; 2 géneros de HE del orden Entomophthorales (Batkoa sp. y Entomophthora sp.) de los cuales no se logró su aislamiento. Se reporta por primera ocasión, la incidencia natural de Simplicillium lanosoniveum y Batkoa sp. asociados a D. citri en Colima, México. Por la incidencia con la que se encontró a H. citriformis, podría considerarse como un buen candidato para el control biológico del psílido D. citri, que al igual que las especies de Entomophthorales, abren la posibilidad de explorar su potencial como agentes microbianos de este psílido.
Se registra la presencia de tres especies de escarabajos ambrosiales del género Xyleborus (Curculionidae: Scolytinae) en árboles de aguacate (Persea americana) de Colima, México. Se trata de Xyleborus affinis Eichhoff, X. volvulus Fabricius, y X. spinulosus Blandford.
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