Laboratory studies on effect of pesticides on entomopathogenic fungus, Verticillium lecanii

Abstract

The effect of fungicides and bactericides on Verticillium lecanii was evaluated both on agar plates, and on larvae of the greenhouse whitefly, Trialeurodes vaporariorum in the laboratory. Polyoxin, procymidone, sulfur, mepronil and copper hydroxide were harmless to conidial germination of the fungus on agar plates and showed no effect on the mortality of the insect when larvae were inoculated with a conidial suspension mixed with each. Triflumizole, dithianon, chinomethionat and zineb were highly toxic to conidial germination of the fungus on agar plates. However, when larvae were inoculated with conidial suspension mixed with each at a concentration sufficient to inhibit conidial germination, larvae were killed at percentages of 39%, 54%, 72% and 100%, respectively. Reduction of larval mortality by treatment with triflumizole was not observed 48 h or more after inoculation. Polyoxin, sulfur, mepronil, procymidone, copper hydroxide, dithianon and zineb were harmless to mycelial growth producing conidia on the surface of larvae killed by the fungus, while triflumizole, chinomethionat, anilazine and benomyl were toxic to mycelial growth.