From the Sea to Mosquito Control: The Potential of Halymenia dilatata Marine Alga as an Eco-Friendly Mosquitocidal Agent

Abstract

A marine-derived red alga, along with their active constituents, were actively screened for their biocontrol potential against major insect pests. The current study explored the larvicidal activity of crude methanolic extracts of the red alga Halymenia dilatata (Mx-Hd) against Aedes aegypti (Linn.), and their enzyme inhibition, repellent activity, and non-target toxicity was screened against non-target species. The toxicity of Mx-Hd to exposed larvae was dose-dependent, and it was significant at the maximum concentration of 100 ppm (parts per million) across the second, third, and fourth instars of Ae. aegypti. The LC50 and LC90 Mx-Hd concentrations for second-instar larvae were 37 and 93 ppm, respectively. Moreover, the level of major detoxifying enzymes was altered in response to the Mx-Hd treatment. The repellent activity of Mx-Hd showed maximum repellent protection at 100 ppm dosage for up to 210 min. The toxicity against non-target species showed that Mx-Hd was safe or less toxic at the prominent dosage (1000 ppm). The photomicrography results provided a prominent damage rate in fourth-instar midgut cells and tissues treated with Mx-Hd. Overall, the present study delivered an insect toxicological screening study of bioactive red alga extracts against a dengue mosquito vector, as well as a baseline for better commercialization of bioactive insecticides. Also, the bioeconomy of algal-based pesticides in managing mosquito larvae presents an exciting avenue for sustainable and eco-friendly pest control.