Background: Mosquito-borne pathogens constitute a major health problem worldwide. The extermination of the mosquito remains a significant issue in public health. Chemical insecticides have been used to control mosquitoes for decades. However, resistance has become a limiting factor for their control. The anthranilic diamide insecticides possess excellent insecticidal activities against Lepidoptera and its resistant strains by draining internal calcium stores on activating insect ryanodine receptors. However, the reports on the effect on mosquitoes are scarce and hence a series of novel anthranilic diamides comprising acyl thiourea substructure were synthesized and their insecticidal activities against three vector mosquito larvae namely, Culex quinquefasciatus, Aedes aegypti and Anopheles stephensi were evaluated as per WHO protocol. Also investigated the morphological observations of treated larvae.
Results: Novel anthranilic diamides containing an acyl thiourea substructure were synthesized and structures were established by 1 H nuclear magnetic resonance (NMR), 13 C NMR, Fourier transform infrared (FTIR) and high-resolution mass spectrometry (HR-MS). Mosquito larvicidal activity of the title compounds 6-a-s revealed that compound 6-l exhibited marked larvicidal activities against C. quinquefasciatus and A. aegypti 3rd instar larvae with median lethal concentrations (LC50 ) values of 0.0044 mm and 0.0070 mm, respectively, for 48 hours of treatment. Compound 6-g exhibited larvicidal activity against An. stephensi with LC50 value of 0.0085 mm. Peculiar morphological alterations in the body of the treated larvae leading to death were observed on microscopic examination.
Conclusion: Novel anthranilic diamides containing an acyl thiourea substructure were designed, synthesized and characterized. Their bioassay results demonstrated significant mosquito larvicidal activity with striking morphological alterations in the body, which should ensure forthcoming designs of highly active diamide derivatives as mosquito larvicides. © 2022 Society of Chemical Industry.
Keywords: WHO protocol; acyl thiourea; anthranilic diamides; mosquito larvicides; vector-borne disease.
© 2022 Society of Chemical Industry.