Larvicidal and oviposition deterrent activity of sesquiterpenes from the red seaweed Laurencia johnstonii against Aedes aegypti

Aedes aegypti is the main disease vector of dengue, chikungunya, and Zika. Pest control efforts to combat these diseases have focused on developing insecticides based on novel active compounds. Laurencia , a genus of red seaweeds, is an important source of brominated compounds, particularly sesquiterpenes, with antifungal, antimalarial, larvicidal, and insect-repellent properties. The objective of the study was to assess larvicidal and oviposition deterrent activity of Laurencia johnstonii against Ae. aegypti . Laurencia johnstonii ethanolic extract and fractions were evaluated against third instar Ae. aegypti larvae (New Orleans strain). All fractions exhibited larvicidal activity. The most active fraction, F2A (LC 50 = 240 μg mL -1 ), was analyzed by GC/MS, and six sesquiterpenes were identified. The major compound, laurinterol, was isolated and identified by NMR analysis. Acetylcholinesterase (AchE) inhibition is an action mechanism employed to identify larvicidal compounds and was identified in the active fraction. Due to the chemical diversity and biological activity of Laurencia species, L. johnstonii is a notable potential source of larvicidal compounds.