Synthesis and Insecticidal Evaluation of Novel N-Pyridylpyrazolecarboxamides Containing an Amino Acid Methyl Ester and Their Analogues

On the basis of the commercial insecticide chlorantraniliprole, a series of novel N-pyridylpyrazolecarboxamides containing an amino acid methyl ester and their analogues were designed and synthesized. Their chemical structures were established on the basis of corresponding H-1 NMR spectroscopy, C-13 NMR spectroscopy, elemental analysis, and single-crystal X-ray diffraction analysis. The insecticidal activities of the new compounds against oriental armyworm (Mythimna separata) and diamondback moth (Plutella xylostella) were evaluated. The results of bioassays indicated that most of the compounds showed moderate to high activities at the tested concentration, of which the compounds 6 containing a methyl acrylate substructure had excellent larvicidal activity; for example, 6a displayed 100% larvicidal activity against P. xylostella at the concentration of 0.005 mg/L, whereas the activities of both compounds 6g and 6h against M. separata were 100% at 2.5 mg/L. The calcium imaging technique experiment results showed that novel compound 6 could elevate the calcium concentration in the cytoplasm. Furthermore, this study also provided evidence that compound 6h activates inositol 1,4,5-trisphosphate (IP3) sensitive intracellular calcium release channels in the endoplasmic reticulum of Spodoptera exigua third-instar larva neurons.