Tarbiat Modares University Journal of Agricultural Science and Technology 1680-7073 27 4 2025 07 01 Annual Population Dynamics and Daily Activity Rhythm of Adult Oriental Hornets (Vespa orientalis), an Important Pest of Iranian Honeybee in Ahvaz, Iran 751 762 17047 10.22034/JAST.27.4.751 EN Narges Karam Kiani Department of Plant Protection, College of Agriculture, Shahid Chamran University of Ahvaz, Ahvaz, Islamic Republic of Iran. Arash Rasekh Department of Plant Protection, College of Agriculture, Shahid Chamran University of Ahvaz, Ahvaz, Islamic Republic of Iran. Parviz Shisheh Bor Department of Plant Protection, College of Agriculture, Shahid Chamran University of Ahvaz, Ahvaz, Islamic Republic of Iran. Gholamhosein Tahmasbi Department of Honeybee, Agricultural Research, Education and Extension Organization (AREEO), Animal Science Research Institute of Iran, Karaj, Islamic Republic of Iran. Journal Article <span>The Oriental hornet, Vespa orientalis L. (Hymenoptera: Vespidae), is one of the most important and serious enemies of honeybees. In this study, the annual population dynamics and daily activity rhythm of Oriental hornet were examined, based on the number of adults trapped in an apiary located in Ahvaz (southwest of Iran) during a period of two years (January 2021 to December 2022). Samplings were performed using the box traps available in the market. The bait used in the traps was fresh chicken liver, with the traps checked daily in four time periods. The results revealed that the first overwintering queens (gynes) emerged in March and two population peaks of newly emerged hornet workers occurred during the year, one in July and the other in October. </span><span>In late November and early December, no adult hornet was trapped. The daily activity rhythm of adult hornets was observed mostly during </span><span>9 – 12 hr, almost twice as much as in the afternoon period (12 – 15 hr). The lowest </span><span>activity </span><span>was recorded in the evening period and night (6 pm - 9 am). During both sampling years, the seasonal abundance of adult hornets displayed a significant positive correlation with air temperature and a significant negative correlation with relative humidity. By comparing the results of our findings with other studies performed in the same and different climate zones, it can be hoped to present effective methods to control the population of </span><span>V.</span><span> orientalis</span><span>, especially in areas that have extensive beekeeping.</span> https://jast.modares.ac.ir/article_17047_d118d975f3cdf403187a078f3a06f866.pdf