Objective The ryanodine receptor (RyR) of Hyphantria cunea was involved in the toxic mechanism of chlorantraniliprole to Hyphantria cunea, and the molecular docking mode of RyR and chlorantraniliprole was explored. The study provided a theoretical basis for analyzing the molecular mechanism of RyR gene of Hyphantria cunea in response to chlorantraniliprole stress.

Method The full-length cDNA of RyR gene was cloned from Hyphantria cunea. The temporal and spatial expression patterns of RyR gene and the expression level of RyR gene in Hyphantria cunea under sublethal concentration of chlorantraniliprole stress were analyzed by real-time fluorescence quantitative RT-PCR. The RyR gene of Hyphantria cunea was silenced by RNAi technology, and the survival rate of silencer under chlorantraniliprole stress was determined to explore the regulation of RyR gene of Hyphantria cunea on chlorantraniliprole resistance. The molecular docking of chlorantraniliprole and RyR was analyzed by Discovery Studio 2019 Client software. The docking situation was analyzed by binding energy and visualization.

Result (1) The median lethal concentration (LC₅₀) and sub-lethal concentration (LC₃₀) of chlorantraniliprole were 21.40 μg/L and 11.13 μg/L for 72 h, respectively, indicating that chlorantraniliprole had high biological activity against the 3rd instar Hyphantria cunea larvae. (2) The relative expression of RyR gene in the 3rd instar Hyphantria cunea larvae increased firstly and then decreased with time under the treatment of chlorantraniliprole LC₃₀ concentration (11.13 μg/L). The relative expression of RyR gene in 48 h and 72 h was 2.6- and 1.5-fold of that in control group, respectively. (3) The survival rate of Hyphantria cunea with RyR gene silencing was 73.33%, while that of control group with GFP gene silencing was 46.66% under LC₃₀ stress of chlorantraniliprole at 72 h. Silencing RyR gene significantly reduced the sensitivity of 3rd instar Hyphantria cunea larvae to chlorantraniliprole. (4) Molecular docking showed that the binding energy of RyR and chlorantraniliprole was −31.35 kJ/mol, and there were hydrogen bonds and van der Waals force between them to make them stable.

Conclusion These results clarify the molecular mechanism of RyR gene in response to chlorantraniliprole stress, and further understand the structure of RyR in Hyphantria cunea and provide a theoretical basis for the development of targeted insecticides.