Sublethal effects of Beauveria bassiana on life table parameters of two–spotted spider mite, Tetranychus urticae (Acari: Tetranychidae)

Abstract

Effects of the entomopathogenic fungus Beauveria bassiana were studied on life table parameters of two-spotted spider mite, Tetranychus urticae feeding on bean and cucumber under laboratory conditions. The developmental periods for all immature stages were not affected by fungal infection on each host plant but the duration of larval stage was significantly longer on bean. The female and male longevity, oviposition period and fecundity were significantly lower on fungus-treated mites but were not different between two host plants. Significant reductions were found on the intrinsic rate of increase (r _m ), the net reproductive rate (R ₀), the finite rate of increase (λ), the mean generation time (T _c ) and the population doubling time (D _t ) as a result of mycosis. Only the mean generation time (T _c ) was influenced considering the effect of host plant, which was shorter on cucumber.

Keywords:

• Beauveria bassiana
• sublethal effect
• life table
• Tetranychus urticae
• host plant

Acknowledgements

This publication is a part of the first author's M.Sc. thesis funded by the University of Tehran and Center of Excellence for Biological Control of Plant Pests, which we thank for their financial support. Mahmood Fazeli was greatly acknowledged for his technical help.