Contact toxicity of ethanolic Syzygium aromaticum flower-bud extract against adult Aedes and Culex mosquitoes as livestock disease vectors: a bottle bioassay

Abstract

Mosquitoes are important vectors of pathogens, whose bites cause significant health and economic burdens. In the livestock sector, these pests significantly reduce animal productivity and transmit critical veterinary pathogens. Chemical-based repellents pose risks, making plant-derived alternatives like clove (Syzygium aromaticum) a promising candidate due to its bioactive compounds. This study evaluated the contact toxicity of ethanolic Syzygium aromaticum flower-bud extract against adult Aedes and Culex mosquitoes using a bottle bioassay. Experimental groups consisted of four treatment concentrations (0.5%, 1%, 3%, and 5%), a positive control, and a negative control. The study employed a completely randomized design with three replicates of 30 mosquitoes each, totaling 540 mosquitoes assessed hourly for seven hours. Results demonstrated that clove extract at 3% concentration achieved 100% knockdown activity within three hours, while 5% concentration induced complete knockdown activity within the first hour of observation. This observed efficacy indicates contact toxicity rather than repellency, suggesting that the extract warrants further investigation for development as a potential botanical contact insecticide.