Population fluctuation and determination of infestation rate of cotton bollworm [Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae)] in second crop cotton fields in Söke Plain

The cotton bollworm [Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae)] is one of the most important pests of cotton and causes significant crop losses in cotton, especially generative organs, by doing damage. This study was carried out in three neighborhoods of Söke district in second-crop cotton fields where delta-type sexual attractant traps were set in order to determine the adult population fluctuation and infestation rate of the cotton bollworm in 2023 and 2024. For this purpose, three second-crop cotton fields were determined in the Akçakonak, Doğanbey, and Güllübahçe neighborhoods, and the adult individuals in the traps were counted regularly. In addition, the infestation rate of cotton bollworm was determined by checking 100 squaers, 100 flowers, and 100 bolls. Cotton plants with pest eggs, larvae, and/or larval damage on squares, flowers, and bolls are recorded as infected. The infection rate was calculated as a percentage using the numerical data obtained. The number of adult individuals in the traps set to determine the population fluctuation of cotton bollworm reached the highest level in September 2023 in the Akçakonak neighborhood and in July in the Doğanbey and Güllübahçe neighborhoods. In 2024, the number of adult individuals reached the highest level in September in the Akçakonak, Doğanbey, and Güllübahçe neighborhoods. The infection rate was recorded as 57, 61, and 45% in the Akçakonak, Doğanbey, and Güllübahçe neighborhoods in 2023, respectively, and 12, 16, and 16% in 2024, respectively. In the cotton fields where the population of the cotton bollworm was monitored, the number of adult individuals caught in traps in 2023 was found to be higher than in 2024. In parallel with this, the rate of infestation caused by the pest in cotton squaers, flowers and bolls was observed to be higher in 2023. In conclusion, in this study conducted to determine the population fluctuation and infestation rate of the cotton bollworm, it was concluded that monitoring the adult individuals with delta-type sexual attractant traps is important in determining the time of control and in deciding on the control.