Larvicidal and antifungal efficacy of Lasiodiplodia theobromae ethanolic extract against Aedes aegypti larvae and Colletotrichum spp. strains

The larvicidal and fungicidal properties of a crude ethanolic extract from Lasiodiplodia theobromae (Botryosphaeriaceae) were evaluated in vitro against Aedes aegypti larvae and three phytopathogenic Colletotrichum species ( C. brevisporum , C. chrysophyllum , and C. siamense ). Fungi are known to produce bioactive metabolites useful for pest and disease management, offering alternatives to synthetic chemicals. L. theobromae was isolated from limestone quarries in San Francisco de Campeche, Mexico. Mycelial biomass was obtained via submerged fermentation, and metabolites were extracted using ultrasound-assisted ethanol extraction. Larvicidal activity was assessed on second-instar A. aegypti larvae by measuring mortality and the Relative Growth Index (RGI), while fungicidal activity was tested against Colletotrichum strains. Chemical characterization using Gas Chromatography–Mass Spectrometry (GC-MS) identified alkaloids, phenolic compounds, terpenes, and flavonoids. Complete larval mortality (100%) was observed at 72 h, with LC₅₀ and LC₉₀ values of 487.59 ppm and 598.15 ppm. Concentrations above 600 ppm reduced RGI to zero, indicating inhibition of larval growth. Fungicidal activity was observed at 5,000–20,000 ppm against all tested species. These results support L. theobromae as a source of bioactive metabolites for vector and pathogen management.