The bean farms in Iran are increasingly suffering from two-spotted spider mite (TSSM) herbivory, which is intensified with the gradual increase in temperature and decrease in relative humidity coinciding with the flowering time in the common bean. Limited genetic variability for resistance to TSSM is a major bottleneck in the development of resistant common beans. Hence, this study aimed to evaluate the response of a diverse panel of 104 common bean genotypes to TSSM infestation during reproductive stages. The experiment was conducted in the form of an augmented randomized complete block design under TSSM-infested and non-infested conditions. The less susceptible genotypes had more grain yield, number of pods, plant height and leaf chlorophyll content, but also, they showed less reduction in these traits under TSSM herbivory condition relative to the more susceptible genotypes. The spider mite laid more eggs on the leaves of more susceptible beans creating a negative density dependence condition, while there was a greater nutritional contribution per adult mite on the leaves of less susceptible common beans. Variance components estimation highlighted grain yield, number of pods, plant height and 1,000-grain weight of the common bean with the higher genotypic variances compared to environmental variances. The findings provide a phenotypic screening procedure of common bean to determine the main plant traits contributing to genetic TSSM resistance under field conditions. This study concludes that pole-type genotypes of common bean would tolerate the mite feeding more than bush-type genotypes during reproductive stages.

中文翻译：

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菜豆（Phaseolus vulgaris）对草食性叶螨反应的实地研究

伊朗的豆类农场越来越多地遭受二斑叶螨 (TSSM) 食草动物的侵害，随着温度的逐渐升高和相对湿度的降低，恰逢普通豆类的开花时间，这种情况会加剧。TSSM 抗性的有限遗传变异是抗性普通豆类开发的主要瓶颈。因此，本研究旨在评估 104 种常见豆类基因型在生殖阶段对 TSSM 侵染的反应。该实验在 TSSM 侵染和非侵染条件下以增强随机完整区组设计的形式进行。较不敏感的基因型具有更高的谷物产量、豆荚数、株高和叶绿素含量，而且，相对于更易感的基因型，它们在 TSSM 食草条件下显示出的这些性状减少较少。叶螨在更易感的豆类的叶子上产卵更多，从而形成负密度依赖性条件，而每只成虫在不太易感的普通豆类的叶子上的营养贡献更大。方差分量估计突出了普通豆的谷物产量、豆荚数、株高和 1,000 粒重，与环境方差相比，基因型方差更高。这些发现提供了一种普通豆类的表型筛选程序，以确定在田间条件下有助于遗传 TSSM 抗性的主要植物性状。