General and molecular characterization of Beauveria bassiana and other fungal isolates for the control of Bemisia tabaci whitefly.

摘要

The process of research and development of Hyphomycetes entomopathogenic fungi (EPF) as microbial biocontrol agents requires the identification, characterization and adequate selection of individual fungal species and isolates. The objective of this research was the biological and molecular characterization of five species, Beauveria bassiana, Paecilomyces fumosoroseus, P. farinosus, Verticillium lecanii and Aschersonia aleyrodis which are natural EPF of the whitefly Bemisia tabaci species, and detailed characterization of eight B. bassiana strains for the selection of the best isolate for future commercial development.;Life cycle studies found important differences in terms of the developmental patterns of all five EPF. More importantly, the individual B. bassiana strains showed differing developmental rates but not patterns. A developmental profile model (DPM) was created to enable identification of the best in vitro, which coincided with bioassays of insecticidal activity against B. tabaci whiteflies. These findings indicate for the first time, that the DPM can select EPF for insect pest control performance.;Biophysical characterization on conidiospores surface hydrophobicity and lectin binding showed significant differences among the species. Lectin binding studies showed different isolates fell into three categories; (i) strong to moderate, (ii) moderate to weak and (iii) weak or no binding. Beauveria bassiana strains and V. lecanii AE405M2 fit into the first and second categories, whereas A. aleyrodis AE901M2 and P. fumosoroseus AE511M21, fit into the third category. Together, the biophysical studies, the DPM and Bemisia whitefly bioassays results separated by quality the performance of the strains.;Biochemical characterization using API 50 CHB test to determine carbohydrate metabolism showed two patterns: first, inability to utilize methylated- such and gluconate-derived carbohydrates and second, varying ability to use many of the 48 carbohydrate(s) tested.;EPF characterization by DNA fingerprints employed polymerase chain reaction (PCR) of randomly amplified polymorphic DNA (RAPD) and restriction fragment length polymorphisms (RFLP) analysis. Results of PCR-RAPD with a collection of twelve 10-mer nucleotides selected from one hundred primers used for initially tests allowed the classification of the B. bassiana strains into several RAPD types. Three major isogenicity groups, highly- (three isolates), moderately- (four isolates) and non-isogenic (one isolate) were identified. (Abstract shortened by UMI.).