GERMINATION OF THE ENTOMOPATHOGENIC FUNGUS VERTICILLIUM-LECANII ON SCALES OF THE GLASSHOUSE WHITEFLY TRIALEURODES-VAPORARIORUM

In a series of laboratory experiments, tobacco leaf discs infested with scales of the glasshouse whitefly, Trialeurodes vaporariorum, were immersed in suspensions of conidia of three strains of the entomopathogenic fungus, Verticillium lecanii. The germination of conidia on the insect was recorded and compared with the germination of conidia applied to Czapek-Dox Complete Medium. Laboratory bioassays were performed to record the mortality of whitefly scales exposed to conidia of all three fungal strains. The rate of germination of conidia on the whitefly scales was much reduced compared to that on complete medium. Differences were recorded in the rate of germination of the three strains on complete medium, but not on the whitefly scales. There was no correlation between the pathogenicity of the strains to whitefly scales in laboratory bioassays and the rate of germination on the host.