Ovicidal and Insecticidal Activities of Pyriproxyfen Derivatives with an Oxime Ester Group.

Based on the structural framework of a pyriproxyfen metabolite, nineteen oxime ester derivatives were synthesized via reaction of the carboxylic acids with 4-(2-(2-pyridinyloxy)ethoxy)benzaldehyde oxime. The corresponding structures were comprehensively characterized by ¹H-nuclear magnetic resonance (NMR), ¹³ C-NMR, and electrospray ionization high-resolution mass spectrometry (ESI-HRMS). All of the compounds were screened for their insecticidal activities against Plutella xylostella and Myzus persicae , and for their ovicidal activities against Helicoverpa armigera eggs. The results obtained show that most of the oxime ester derivatives displayed moderate to high insecticidal activities and ovicidal activities at a concentration of 600 ug/mL. In particular, the ovicidal activity of compounds 5j , 5o , 5p , 5q , and 5s was determined to be 100%. Importantly, some of the compounds presented even higher biological activities than the reference compound pyriproxyfen. For example, compound 5 j displayed an insecticidal activity value of 87.5% against Myzus persicae , whereas the activity value of pyriproxyfen was 68.3% at a concentration of 600 ug/mL. Among the synthesized compounds 5 j and 5 s exhibited broad biological activity spectra.
Competing Interests: All authors declare no conflicts of interest.