In vitro virulence of three Lecanicillium lecanii strains against the whitefly, Bemisia tabaci (Genn.) (Hemiptera: Aleyrodidae)

Abstract

Abstract Background Whitefly, Bemisia tabaci (Genn.) (Hemiptera: Aleyrodidae), is one of the most harmful pests in greenhouses and in open fields. Main body The present study aimed to assess in vitro virulence of 3 entomopathogenic fungal strains (EPFs) of Lecanicillium lecanii 3 (V-3), 4 (V-4), and 5 (V-5) against the whitefly, Bemisia tabaci (Genn.) (Hemiptera: Aleyrodidae), by spray method. The 3 disparate bioassays were performed encompassed of conidial concentrations and fungal filtrate of the strains, V-3, V-4, and V-5, and also their binary combinations. In the filtrate bioassay, 2 ml of fungal filtrate of each strain was used. In the conidial bioassay, 3 disparate concentrations (1 × 105, 1 × 106, and 1 × 107 conidia ml−1) were used for each fungal strain, while in the binary combinations (1 ml filtrate + 1 ml conidia) of V-3 × V-3, V-4 × V-4, and V-5 × V-5 were used. Mortality rates against the whitefly were recorded on the 7th day. In the conidial bioassay, maximum mortality rates were found at V-3 strain (90.6%), V-4 strain (78.4%), and V-5 strain (83.6%) at the highest concentration (1 × 107 conidia ml−1) on the 7th day. In the filtrate bioassay, V-3 strain revealed a maximum mortality (93%), V-4 strain (85%), and then V-5 strain (87%) on the 7th day. Moreover, in the bioassay of binary combinations, the highest mortality rate of the whitefly was counted in V-3 × V-3 strain (84.6%), V-4 × V-4 strain (70.6%), and V-5 × V-5 strain (79.8%) on the 7th day. Conclusion All treatments had the potential to control B. tabaci significantly. In all bioassays, the V-3 strain was the extreme virulent, and the filtrate application of V-3 strain was the utmost impressive against B. tabaci.