Biological responses of Tetranychus urticae to five pepper cultivars at two phenological stages of host plants

Abstract

The two-spotted spider mite, Tetranychus urticae Koch (Acari: Tetranychidae) is an important pest of pepper (Capsicum annuum L.). Control of this pest is usually dependent on chemical pesticides. The use of resistant plant cultivars in conjugation with other control tactics generates more effective and long lasting results in management of many pests. In this study we used two-sex life table to evaluate the performance of T. urticae on five pepper cultivars (11983, ES4, Hashemi, Mahali and USL) before and after blooming of host plants. The results showed that the immature time, adult longevity and fecundity differed significantly among cultivars. Before blooming on 11983, the values for the intrinsic rate of increase (r) and the finite rate of increase (λ) were 0.0645 and 1.066 day-1 respectively, which were significantly the lowest; the highest r and λ values was recorded on ES4 which were 0.1347 and 1.144 day-1 respectively. After blooming there was no significant difference in these values among cultivars except for Mahali in which these values were significantly the highest (0.0751 and 1.078 day-1 respectively). Comparing between the phenological stages of host plants (before and after blooming) indicated that after blooming all of the tested pepper cultivars were more resistant to T. urticae. In summary, among the different cultivars tested, the most suitable was ES4 and the least suitable was 11983 before blooming of host plants. After blooming the suitability of host plants changed and decreased significantly.