Population Density of the two-Spotted Spider Mite, Tetranychus urticae (Koch), and its Effect on the Susceptibility of some Cucumber Cultivars in Summer and Winter Plantation

Population activity of the two-spotted spider mite, Tetranychus urticae (Koch) inhabiting cucumber plants was studied during two successive seasons of 2020 and 2021 at Manflout and Qusia districts, Assiut governorate, Egypt. The eight tested cucumber cultivars slightly differed in population densities of T. urticae stages (motile and immotile) in both seasons and areas. The obtained results showed that the spider mite T. urticae activity increased in summer plantation during the two studied seasons. Bahie and Barcoda cultivars showed the highest numbers of the pest all stages in Manflout during the summer of 2020, with an average of 30.86 individuals for Bahie cultivar and 40.47 individuals for Barcoda one. Meanwhile, 39 and Barcoda cultivars gave an average of 38.04 and 23.20 individuals at Qusia during both studied seasons. The current study found that all cucumber cultivars were sensitive to the infestation with the two-spotted spider mite, but the sensitivity varies from one cultivar to another.