Demographic assessment of Tetranychus urticae (Acari: Tetranychidae) on five bean cultivars: an age-stage, two-sex life table approach

The two-spotted spider mite, Tetranychus urticae Koch, is a highly destructive pest that causes significant economic losses to crops worldwide. This study evaluated the host suitability of five bean cultivars (IPSA Seem 1, IPSA Seem 2, BARI Seem 1, Noldog, and Goalgadda) by comparing population growth and life table parameters of T. urticae. Experiments were performed under controlled conditions (25 ± 2°C, 60 ± 10% RH, and a 16:8 L: D photoperiod) following the age-stage, two-sex life table theory. Significant differences were observed among cultivars. Female developmental time was shortest on IPSA Seem 2 (10.43 days) and longest on BARI Seem 1 (11.98 days). IPSA Seem 2 was the most suitable host, supporting the highest fecundity (90.97 eggs female−1), net reproductive rate (R0 = 61.30), intrinsic rate of increase (rm = 0.2714 day−1), and finite rate of increase (λ = 1.3118 day−1). Conversely, the local cultivar Goalgadda was the least suitable, supported the lowest fecundity (51.04 eggs female−1), R0 (35.73), rm (0.2294 day−1), and λ (1.2578 day−1). These demographic parameters indicated that Goalgadda exhibits resistance to T. urticae. The findings provide critical information for selecting less suitable bean cultivars, thereby strengthening integrated pest management strategies for this pervasive mite.