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 wit h scales of the glasshouse whitefly, Trialeurodes vaporariorum, were i mmersed in suspensions of conidia of three strains of the entomopathog enic fungus, Verticillium lecanii. The germination of conidia on the i nsect was recorded and compared with the germination of conidia applie d to Czapek-Dox Complete Medium. Laboratory bioassays were performed t o record the mortality of whitefly scales exposed to conidia of all th ree fungal strains. The rate of germination of conidia on the whitefly scales was much reduced compared to that on complete medium. Differen ces were recorded in the rate of germination of the three strains on c omplete medium, but not on the whitefly scales. There was no correlati on between the pathogenicity of the strains to whitefly scales in labo ratory bioassays and the rate of germination on the host.