Assessment of the Impact of Deltamethrin on the Different Life Stages of Culex pipiens (Diptera: Culicidae)

الملخص

Abstract
The present study aimed to evaluate the effect of the insecticide Deltamethrin on various life stages of the mosquito Culex pipiens. The research was conducted on Culex pipiens in Salah al-Din Governorate, Tikrit District, from early October to the end of November 2023, and again from March to the end of May 2024. Statistical analysis revealed a significant effect of Deltamethrin concentration and exposure duration on egg incubation periods. The 2.00% concentration yielded the highest incubation period after 72 hours (4.00 days), which was not significantly different from the 1.50% concentration. The shortest incubation period (3.02 days) was recorded at 0.50% concentration after 24 hours. A significant impact was also observed on egg hatching rate, with 0.50% concentration achieving the highest hatchability (51.57%), while 2.00% resulted in the lowest (16.39%). The third-instar larval mortality rate showed significant variation based on insecticide concentration and exposure time. The highest mortality (98.97%) was recorded at 2.00% after 72 hours, whereas the lowest (37.04%) was noted at 0.50% after 24 hours. Similarly, fourth-instar larval mortality was significantly affected, with the highest value (93.92%) observed at 2.00% after 72 hours and the lowest (33.19%) at 0.50% after 24 hours.