خسارت کرم برگخوار چغندرقند Spodoptera littoralis (Boisduval) در تاریخ کشتهای مختلف در شهرستان‌های شمالی خوزستان

The beet armyworm, Spodoptera littoralis, is a significant pest of sugar beet, particularly during the early stages of plant growth, and can cause considerable damage to the crop. This study aims to investigate the effect of planting dates on the extent of damage caused by this pest in the major sugar beet cultivation areas of northern Khuzestan Province (Shush, Dezful, and Andimeshk counties). Population assessment was conducted by installing pheromone traps at a density of 2 per hectare and performing weekly sampling. The pheromone traps were installed concurrently with planting, and damage assessment was carried out by counting the damaged plants within one square meter frames and determining the damage percentage for each plant. Damage was monitored from planting time until the weather cooled in early December (when the pest population declined) over two cropping seasons (2022-2024). The results showed that in the Sorkheh area of Shush County, with sandy soil and a planting date of October 22, the adult population attracted to the traps was 4 adults per week, the larval count was 0.28 ± 0.01 larvae per plant, and the damage rate was 3%. In Dezful, with a planting date of September 22, the average adult population attracted to the traps was 10 adults per week, the larval count was 1.35 ± 0.02 larvae per plant, and the damage rate was 12%. Conversely, the Azadi area of Andimeshk County, with a planting date of September 29, had 15 adults per trap, Hoor Riahi with a planting date of October 2 had 14 adults per trap, and Bon Mala with a planting date of October 7 and sandy clay soil had 17 adults per trap, with damage rates ranging from 15-20%. It appears that the planting date does not directly affect the extent of damage, and other environmental factors significantly influence the severity of damage.