, a Potential Microbial Biolarvicide.

Infected mosquitos from the genus have become one of the world's most influential contributors to human morbidity and death. To explore new biopesticides with activity against , , a species related to the subspecies group of , was investigated. Six metabolites, aureothin, allo-aureothin, deoxyaureothin, 4',7-dihydroxy isoflavone, 2-methyl-5-(3-indolyl)oxazole, and 2-ethyl-5-(3-indolyl)oxazole were isolated, and chemical structures, were elucidated based on one- and two-dimensional NMR spectroscopy analyses and HRMS. The larvicidal activity of these compounds was evaluated. Only two isomeric compounds, aureothin and allo-aureothin, showed larvicidal activity against with LC values of 1.5 and 3.1 ppm for 24 h post-treatment, respectively, and 3.8 and 7.4 ppm for 48 h post-treatment, respectively. The crude extract of also demonstrated potent larvicidal activity with LC values of 1.46 and 1.2 ppm for 24 and 48 h post-treatment, respectively. Deoxyaureothin, a furan ring reduced form of aureothin, showed no activity against . The hybrid imported fire ants activity of aureothin was also evaluated, but it did not show any activity at the highest dose of 62.5 μg/g. Described here is the first report on a bioassay-directed investigation of the secondary metabolites of and biological evaluation of isolated compounds aureothin and its isomer and intermediates as potential microbial larvicides. and crude extracts thereof are a promising source of potential microbial biolarvicides.