Larvicidal potential of ether extract, and its derivatives fatty acids, and fatty acid methyl esters from Tecoma stans seeds: Bioprospecting for an effective insecticide

In the work, the larvicidal potential of ether extract (EE), and its hydrolyzed products enriched with fatty acids (FA), and fatty acid methyl esters (FAME) obtained from Tecoma stans seeds was evaluated. EE, and FAME were analyzed by Gas Chromatography-Mass Spectrometry (GC-MS) and three samples were evaluated in a preliminary screen for larvicidal activity against Culex quinquefasciatus at concentrations of 31.25, 62.5, 125, 250, 500, and 1000 μg/mL. The larvicidal efficacy of all samples was assessed at 24, 48, and 144 h post-treatment, detecting the movement of each larva. The data obtained were subjected to probit analysis to determine the lethal concentrations that killed 50 % and 90 % (LC₅₀ and LC₉₀) of the treated larvae. In EE, the phytosterol γ-sitostenone was characterized as the predominant component (30.40 %), while in FAME the presence of methyl palmitate (25.01 %), and methyl stearate (22.14 %) stood out. Notable larvicidal activity was detected after 24 h of treatment. EE exhibited moderate toxicity against C. quinquefasciatus (LC₅₀ = 193.34 μg/mL), while FAME was slightly toxic (LC₅₀ = 269.43 μg/mL), and FA, the most promising product, presented an LC₅₀ = 20.06 μg/mL. The results together demonstrate that extracts, and hydrolyzed products from T. stans seeds may be useful as eco-friendly, economical, and effective larvicidal agents. However, additional studies are needed to search for bioactive compounds of plant extracts, and their derivatives that exhibit larvicidal activity, and their modes of action.