University of Isfahan Taxonomy and Biosystematics 3115-9001 14 53 2023 01 21 Population Fluctuation and Spatial Distribution of Thrips in Bean Farms (Phaseolus Vulgaris L.) in Lorestan Province, West of Iran تغییرات جمعیت و پراکنش فضایی تریپس‌‌های مزارع لوبیا (Phaseolus vulgaris L.) در استان لرستان، غرب ایران 77 92 27458 10.22108/tbj.2023.136883.1226 EN Hadis Mohammadi Noori Ph.D. student, Department of Plant Protection, Faculty of Agriculture, Lorestan University, Khorramabad, Iran Shahriar Jafari Associated Professor, Department of Plant Protection, Faculty of Agriculture, Lorestan University, Khorramabad, Iran Majid Mirab-balou Associated Professor, Department of Plant Protection, College of Agriculture, Ilam University, Ilam, Iran Journal Article 2023 02 19 Considering the significant damage caused by thrips species to bean crops, this study investigated population fluctuations, species diversity, and the spatial distribution of thrips in relation to the growth stages of red beans (Phaseolus vulgaris L.) in bean farms of Selseleh county (Lorestan province, west of Iran). Sampling was conducted from the time the beans developed two leaves until the leaves dried, in two farms located in the villages of Cham-Takleh and Dartang during 2021. The sampling in the farms followed a W-shaped pattern. In each sampling, 20 leaves were selected, and thrips were collected by shaking the leaves over a white tray. This study identified 12 species of thrips. Among them, the highest frequency was observed in onion thrips, Thrips tabaci Lindeman (69.43%). The results of population fluctuation showed that in Cham-Takleh, the highest densities of onion thrips and flower thrips were 166.35 ± 4.99 and 16.85 ± 1.38, respectively, while in Dartang, they were 159.3 ± 3.61 and 22.6 ± 1.32 on average. In both locations, the highest values of biodiversity indices were observed during the reproductive stage of the bean. The highest values of the Shannon-Wiener, Simpson, Pielou evenness, and Margalef richness indices in Cham-Takleh were 2.94, 0.93, 0.95, and 2.98, respectively, and in Dartang, they were 2.89, 0.91, 0.94, and 2.74. Overall, the results of this study indicated that the population peak of onion and flower thrips occurred during the reproductive and pod development stages of beans, with their density gradually decreasing in the farms. Given that thrips can cause significant damage to bean crops at this stage, appropriate management measures are advisable for farmers. Introduction Bean (Phaseolus vulgaris L.) (Fabaceae) is one of the most widely cultivated legume plants in many countries. Lorestan province is one of the most important bean-growing regions in Iran, with a cultivated area of 15,887 hectares. Several insects with piercing-sucking mouthparts, such as thrips, leafhoppers, aphids, and plant bugs, are pests on beans. However, thrips, the most dangerous among these pests, are the focus of this research. Thrips can attack beans from the moment the seedlings emerge from the ground through to the flowering stage. Considering the significant damage caused by thrips species to bean crops, the present study investigates the population fluctuation, species diversity, and spatial distribution of thrips in relation to the growth stages of beans in the farms of Selseleh County (Lorestan province, west of Iran). Materials and Methods In this study, sampling was conducted from the time the bean plants developed two leaves until the leaves dried, in two farms located in the villages of Cham-Takleh and Dartang during the year 2021. The sampling in the farms followed a W-shaped pattern. In each sampling event, 20 leaves were selected, and thrips were collected by shaking the leaves over a white tray. For accurate counting of thrips, a stereomicroscope was used; some samples were separated, microscopic slides were prepared from selected samples, and the number of thrips was recorded. The spatial distribution of both immature and adult thrips was estimated using Taylor’s power law and Iwao’s patchiness regression methods. Biodiversity indices were calculated using PAST software. This study included counting of larvae and adult insects. Additionally, to investigate the effect of temperature and humidity on thrips population density, a multiple linear regression was employed, correlating average daily temperature, average daily relative humidity, and thrips population density on each sampling date. For data analysis, Excel 2016 was used to calculate the relative frequency, and T-Test was applied to compute biodiversity indices and compare diversity data between different regions. Statistical tests were performed using SPSS version 23. Results and Conclusion In this study, 12 species of thrips were collected and identified. Amongst them, the highest percentage of frequency was related to onion thrips, Thrips tabaci Lindeman (69.43%) and flower thrips, Frankliniella intonsa (Trybom) (12.11%). The frequency (%) of the other species are as follows: Aeolothripidae: Aeolothrips intermedius Bagnall (6.63), A. collaris Priesner (1.13); Thripidae: Tenothrips frici (Uzel) (4.76), Thrips trehernei Priesner (2.8), Odontothrips confusus Priesner (1.5), Scolothrips longicornis Priesner (1.3), Neohydatothrips gracilicornis (Williams) (0.09), Microcephalothrips abdominalis (Crawford) (0.08); Phlaeothripidae: Haplothrips reuteri (Karny) (0.1), and H. globiceps Bagnall (0.07). The results of population fluctuation showed that in Cham-Takleh, the highest density of onion thrips and flower thrips was 166.35 ± 4.99 and 16.85 ± 1.38, respectively. In addition, in Dartang the highest density was 159.3 ± 3.61 and 22.6 ± 1.32 on average. Also, in both sites, the highest values of biodiversity indices were observed in the reproductive stage of beans. The highest values of Shannon-Wiener, Simpson, Pielou evenness, and Margalef richness indices in Cham-Takleh were 2.94, 0.93, 0.95, and 2.98, and in Dartang were 2.89, 0.91, 0.94 and 2.74, respectively. In general, the results of this study showed that the population peak of onion thrips and flower thrips was observed in the reproductive and development of pod stages of beans, and their density gradually decreased in the farms. Appropriate management measures can be provided for farmers considering that at this stage of the bean, thrips can cause a lot of damage to the bean crops. Funding Funding was provided by the Department of Plant Protection, Faculty of Agriculture, Lorestan University, Khorramabad, Iran.

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