Brazilian Cerrado biome essential oils to control the arbovirus vectors Aedes aegypti and Culex quinquefasciatus

Abstract

Insecticides have been used not only to control pests in agricultural production, but also in integrated vector management strategies to reduce populations of mosquitoes, and, consequently, decrease transmission of pathogens they carry. The Aedes aegypti mosquito is a vector of dengue, Zika, chikungunya and yellow fever viruses, whereas the common mosquito Culex quinquefasciatus is a vector of human filariasis and the West Nile virus. Natural insecticides constitute effective ecofriendly alternatives to synthetic control agents. Thus, we investigated the larvicidal, adulticidal and repellent activity of six Brazilian Cerrado plant essential oils extracted by hydrodistillation, together with their major components identified by GC/MS: p-cymene, (R)-(+)-limonene, (S)-(-)-limonene and (-)-β-pinene. The species were selected taking into account the fact they are plants commonly found in this biome, easy to be collected and being still poorly studied in terms of their activity in the Ae. aegypti and Cx. quinquefasciatus. These essential oils demonstrated activity against (i) Ae. aegypti larvae (24 h): Xylopia aromatica (LC50 12.1 µg/mL), Myrcia dictyophylla (LC50 17.6 µg/mL) and Campomanesia adamantium (LC50 18.0 µg/mL); and (ii) Ae. aegypti adults (after 4 h exposure) with the highest knockdown values observed for C. adamantium (93.8%), Blepharocalyx salicifolius (93.4%), M. dictyophylla (92.5%) and X. aromatica (87.2%). These natural product mixtures also demonstrated repellency to (i) Ae. aegypti: Eugenia dysenterica leaves: spatial activity index (SAI) 0.737; weighted spatial activity index (wSAI) 20.229, B. salicifolius (SAI 0.611; wSAI 14.804) and M. dictyophylla (SAI 0.586; wSAI 8.798); and (ii) Cx. quinquefasciatus: E. dysenterica - Protection (P) 71%, C. adamantium (P 61%) and B. salicifolius (P 60%). B. salicifolius leaves essential oil showed both insecticidal and repellent activity. Our results support the use of Cerrado plant essential oils at low concentrations as a promising alternative vector control strategy.