Chemistry matters: biological activity of Eucalyptus essential oils on mosquito larval mortality

Abstract

The mosquito Aedes aegypti L. (Diptera: Culicidae) is a vector of arboviral diseases such as dengue fever. Currently, the main approach to mosquito control is the application of synthetic insecticides, which can lead to negative environmental impacts and insecticide resistance in mosquito populations. As such, there has been increased interest in developing alternative methods for control of vector populations such as utilizing plant compounds that act as larvicides. The aim of this work is to evaluate the effectiveness of Eucalyptus sp. (Myrtaceae) essential oils for control of Ae. aegypti larvae. The essential oils of seven Eucalyptus species and hybrids were extracted by hydrodistillation and analyzed by gas chromatography coupled to mass spectrometry. The essential oils were further diluted in water with acetone (0.40%) at the following concentrations: 100, 50, 25, and 10 lg ml À1 . Mortality trials were conducted in plastic containers with a solution of ultrapure water and 200 ll of diluted oil for a total volume of 50 ml per treatment. The experiments for each Eucalyptus species/hybrid and concentration were performed in triplicate, using a control containing only water and acetone. Twenty larvae were added to each container and mortality was recorded at 1, 2, 4, and 24 h. The Eucalyptus essential oils showed larvicidal activity in most of the evaluated concentrations, mainly at 50 and 100 lg ml À1 . Eucalyptus benthamii Maiden & Cambage and the hybrid Urograndis displayed the highest larvicidal potential (100% at 24 h) in the 100 lg ml À1 treatment. Larval mortality of Ae. aegypti showed a positive correlation with the compounds c-, o-cymol, o-cymene, terpineol, 3-dodecylfuran-2,5-dione, a-pinene, globulol, and ledol. The most abundant compounds identified in the essential oils were 1,8-cineole and a-pinene. These results highlight the potential of using Eucalyptus essential oils for the isolation of natural larvicidal products.

The Effect of Scale Insects on Growth Parameters of cv. Chardonnay and cv. Sauvignon Blanc Grapevines Grown in a Greenhouse

“…Globulol has been reported from Eucalyptus sp. and has been reported to have insecticidal activity against mosquito larvae [ 33 ]. The next three compounds in importance by VIP scores (phenol, 2-methoxy-3-(2-propenyl)-, 1-nonanol and benzyl alcohol) either changed the sign of the ratio between the two cultivars (first two) or had a much greater absolute value between the two cultivars (benzyl alcohol).…”

Land-use effects on aquatic macroinvertebrate diversity in subtropical highland grasslands streams

“…This finding may be related to the higher litter input of silvi-culture systems compared to grasslands (Table S1). However, silviculture areas may possess high toxicity due to the release of secondary compounds during leaf litter decomposition, thereby simplifying the food web (Carvalho et al, 2019;Gallon et al, 2020;Rezende et al, 2021). Therefore, high α diversity in silviculture systems compared to grasslands can lead to the inference that system litter input was more relevant than secondary compounds released by litter decomposition, because of the fast leaching of allelopathic compounds in leaves (Rezende et al, 2014a).…”

Herbal oils in healthcare: a review

“…Still regarding the Myrtaceae family, it is worth mentioning the studies about the Eucalyptus genus. In short, Gallon et al (2020) aims in their study to evaluate the efficacy of EOs of species of this genus in the control of larvae of Aedes aegypti, in which it can be concluded that the species demonstrated larvicidal activity in most of the evaluated concentrations, highlighting the species Eucalyptus benthamii and the hybrid species urograndis presented higher potential larvicide. Gallon et al (2020) also pointed out that the compound α-pinene was the protagonist responsible for the larval mortality, therefore the compounds present in the eucalyptus EOs have competence to be used as a natural insecticide resource, thus being able to supplement or replace synthetic chemicals in mosquito control programs and exhibiting a formidable potential in the pharmaceutical, medical and mosquito vector control industry.…”