Discovery of Pyrido[1,2-<i>a</i>]pyrimidine Mesoionic Compounds Containing Benzo[<i>b</i>]thiophene Moiety as Potential Pesticide Candidates

Abstract

The increasing evolution of insect resistance has made it challenging for traditional insecticides to control the bean aphid (<i>Aphis craccivora</i> Koch). To address this pending issue, a range of pyrido[1,2-<i>a</i>]pyrimidine mesoionic compounds containing benzo[<i>b</i>]thiophene were designed and synthesized. The biological activity test results of the target compounds indicated that they had moderate to outstanding insecticidal activity against the bean aphid (<i>Aphis craccivora</i>) and moderate insecticidal activity against the white-backed planthopper (<i>Sogatella furcifera</i>). Compound <b>L14</b> exhibited significant insecticidal activity against <i>A. craccivora</i>, with an LC₅₀ value of 1.82 μg/mL, which was superior to triflumezopyrim (LC₅₀ = 4.76 μg/mL). The results of enzyme activity assay showed that compound <b>L14</b> had a definite inhibitory effect on ATPase. Moreover, the proteomics and docking findings of compound <b>L14</b> suggested that it may act on the central nervous system of aphids and interact with nicotinic acetylcholine receptors. Therefore, compound <b>L14</b> is a potentially novel insecticide candidate for further utilization.