Baseline susceptibility, risk assessment of resistance, changes in insecticides sensitivity and fitness after selection of dimpropyridaz in Aphis gossypii Glover (Hemiptera: Aphididae).

Dimpropyridaz as a novel insecticide is registered for the management of many aphid species and other piercing-sucking insects. For the aim to clarify the susceptibility of natural population and the resistance risk of dimpropyridaz in Aphis gossypii in China, the baseline susceptibility, risk assessment, changes of insecticides sensitivity and fitness after selection of dimpropyridaz in A. gossypii were evaluated in present study. The results showed that dimpropyridaz exhibited high activity against 23 field populations of A. gossypii from cotton planting regions in China with LC values ranging from 0.37 to 8.93 mg/L, which indicating a 24.14-fold natural susceptibility variability between the most sensitive and the most selected populations. Based on the dimpropyridaz susceptibilities of 23 field populations, the sensitivity baseline of A. gossypii to dimpropyridaz was established with the LC value as 1.29 mg/L. Additionally, the resistance risk of A. gossypii to dimpropyridaz was evaluated by continuously selecting both a susceptible laboratory population and a field Tulufan population. After 10 selections with dimpropyridaz, no significant dimpropyridaz resistance increased in both populations, with the realized heritability were estimated as 0.01 and 0.04 for the two populations respectively, and this meant low resistance risk to dimpropyridaz of A. gossypii. In addition, the sensitivities of the dimpropyridaz selected population to imidacloprid, acetamiprid and sulfoxaflor displayed some reduction, whereas no significant changes in sensitivity to afidopyropen, carbosulfan and bifenthrin. However, the dimpropyridaz selected population showed a low fitness, with fitness as 0.73. These results provide important information for development of effective resistance management strategies of dimpropyridaz in A. gossypii.