Une technique d'évaluation de la sensibilité variétale au tétranyque tisserand, Tetranychus urticae Koch (Acari: Tetranychidae). Application au haricot, au concombre, à la tomate et au fraisier

Varietal resistance is a major element in the integrated control of spider mites; it is the least expensive and the easiest technique for plant protection. In this context, the purpose of this study was to develop a rapid and reliable technique for evaluating strain susceptibility to spider mites. In laboratory conditions (24 degrees C), >99% mite increase potential was already expressed on d 12 of the oviposition period. The curve of cumulated fecundity, limited to 12 d, and particularly the size of the F1 generation, constitute useful criteria for determining susceptible and resistant varieties. After fitting a logistic function and comparing asymptotic confidence intervals, a statistical analysis could be performed. In this manner, 17 bean, 6 cucumber, 4 tomato and 6 strawberry varieties were tested. Significant differences appeared, and some strawberry varieties may even be considered as totally 'resistant' to Tetranychus urticae.