Biocidal efficacy of olefinic N-alkylamides against Aedes aegypti and Culex quinquefasciatus larvae

Abstract

Mosquito-borne diseases are a major public-health concern worldwide. The development of resistance in mosquitoes to the existing larvicides and the associated-risks necessitates the exploration of novel molecules to control vector-borne pathogens. This study demonstrates that N-alkylamides [2E,4E-N-isobutyl-undeca-2,4-diene-8,10-diynamide (1) and 2E,4E,8Z,10E-N-isobutyl-dodeca-2,4,8,10-tetraenamide (2)] of Acmella ciliata exhibit biocidal action against Aedes aegypti and Culex quinquefasciatus larvae. The LC₅₀ for 1 and 2 were 44.19 and 18.28 ppm against Aedes larvae, and 30.89 and 11.75 ppm against Culex larvae, respectively. We further observed that the chain length, degree of unsaturation, and terminal methylation influence the larvicidal efficacy of N-alkylamides. HPLC-assisted quantification revealed that the content of both 1 (19.01 mg/g) and 2 (68.55 mg/g) was maximum in the flowers of A. ciliata. Thus, this study concludes that N-alkylamides are promising alternatives to control mosquito larvae and can be used as standard for quantitation in test samples.

Graphical Abstract

Keywords:

• Acmella
• Aedes aegypti
• Culex quinquefasciatus
• Larvicide
• N-alkylamide
• Spilanthes

Acknowledgements

RS & NA are grateful to the DST-FIST (Govt. of India), the Department of Biotechnology (Pondicherry University, PU), Department of Chemistry (PU) and the Central Instrumentation Facility (PU) for infrastructure and instrumentation facilities. RS acknowledges the Council of Scientific and Industrial Research (CSIR), New Delhi for JRF/SRF research fellowship [File No: 09/559(0129)/2019-EMR-I].

Disclosure statement

No potential conflict of interest was reported by the authors.

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Funding

The author(s) reported there is no funding associated with the work featured in this article.