Acarological Society of Iran Persian Journal of Acarology 2251-8169 7 2 2026 02 01 A population growth model of Tetranychus urticaeKoch (Acari: Tetranychidae) 193 201 240896 10.22073/pja.v7i2.36245 EN Azadeh Farazmand Department of AgriculturalZoology, Iranian Research Institute of Plant Protection, Agricultural Research Education and Extension Organization (AREEO), Tehran, Iran; E-mail: afarazmand@iripp.ir Masood Amir-Maafi Department of Sunn Pest, Iranian Research Institute of Plant Protection, Agricultural Research Education and Extension Organization (AREEO), Tehran, Iran; E-mail: mamirmaafi@gmail.com Journal Article Two-spotted spider mite, <em>Tetranychus urticae</em> Koch is a serious pest of different crops over the world. Different strategies are used to regulate the population of this mite. To this end, as a first step, a population growth model has been developed for describing the dynamics of <em>T. urticae</em> population growth. In this regard, the population abundance of <em>T. urticae</em> was estimated weekly from 29 June to 29 September 2016 at two bean fields, each field was planted with Goli and Akhtar cultivars, separately. During each sampling period in each field, 30 plants were randomly chosen and a leaf was selected as a sample unit from the middle of a plant, then a simple population growth model was constructed for <em>T. urticae</em> on two bean cultivars. The result showed that <em>T. urticae</em> had a distinct seasonal pattern of abundance but differed between two cultivars. A logistic growth model was developed based on relationship between the cumulative density of <em>T. urticae</em> and time (day) and demonstrated high prediction capability for <em>T. urticae</em> population on Goli (R²= 0.99) and Akhtar (R²= 0.99) cultivars. According to the logistic equation, carrying capacity was recorded 463.9 ± 9.73 (mite/leaf) and 59.67 ± 8.72 (mite/leaf) on Goli and Akhtar cultivars, respectively. Furthermore, it has been shown that the logistic growth model can be used to make population predictions. The model parameters estimated for two different cultivars, providing a new mathematical tool for ecologists to predict two-spotted spider mite outbreaks, and ultimately to develop effective two-spotted spider mite control strategies. https://www.persianacarology.org/article_240896_828a3d12818610d43d285adf75e895c3.pdf