Effects of nanoemulsion and essential oil from the leaves of Ocotea elegans against Dysdercus peruvianus

Abstract

The Dysdercus peruvianus Guérin-Méneville is commonly known as the cotton stainer bug. In this study, it was evaluated the insecticide activity and mode of action of the essential oil from leaves of Ocotea elegans Mez and its nanoemulsion against D. peruvianus. Leaves of O. elegans were extracted by hydrodistillation. The essential oil obtained was analyzed by gas chromatography coupled with electron impact mass spectrometry and flame ionization detector. The essential oil toxicity measured by lethal dose 50 (LD50) and survival rate of insects were recorded. Lastly, an assay was carried out to assess the inhibition of the enzyme acetylcholinesterase to determine a possible mechanism of action of insecticidal activity. The sesquiterpene sesquirosefuran was the major compound detected and corresponds to 92% of the components of the essential oil. The nanoemulsion more stable showed hydrophilic lipophilic balance (HLB 11.74), droplet size 92±1.80 nm, and polydispersity index (PDI of 0.215±0.015). After the topical application of the O. elegans essential oil, significant decreases in the survival of D. peruvianus occurred in a dose-response manner with LD50 = 162.18 μg and the survival rate of the nanoemulsion in D. peruvianus was 10.0±5.47, a better value than in pure essential oil. The acetylcholinesterase inhibition presented inhibition concentration (IC50 = 1.37mg/mL) and mixed type of inhibition. This indicates that the essential oil of leaves from O. elegans and its nanoemulsion are promising candidates for use in integrated pest management programs.

Characterization and Inhibitory Effects of Essential Oil and Nanoemulsion from Ocotea indecora (Shott) Mez in Aspergillus Species

“…The essential oil from the leaves of O. indecora showed approximately 86% of sesquirosefuran, corroborating with the O. indecora chemical profile and sesquirosefuran amount (88-92%) described previously by other authors [29,31].…”

“…The sesquirosefuran has few reports about the molecule bioactivity, mainly insecticide activity [29,31], and none related to its antifungal potential. Sesquiterpenes and furanosesquiterpenes, in turn, have several recognized activities, and among them, Marongiu et al [33] demonstrated activity against several Aspergillus sp.…”

“…The main metabolite related to the Ocotea indecora's essential oil from leaves is the furanosesquiterpene sesquirosefuran. Even though most of the reports are about insecticidal effects [29][30][31], furanosesquiterpenes have several activities recognized in the literature as antioxidant, herbicidal, antibacterial, chemo-preventive agents, and principally for this study, antifungal [32,33]. Thus, essential oils and their possible effects are important research proposals for the biotechnological development of sustainable products.…”

Essential oils from Carapebus sandbank plants as natural controllers against insect pests of importance in Brazilian public health and agriculture

“…The nanoemulsion containing the EO from O. indecora were active on D. peruvianus adult, a Hemiptera cotton pest, presenting a LD 50 equal to 162.18 µg/mL, with a sesquirosefuran oil concentration of 92 % (Nascimento et al, 2020). The leaves EO from the species Myrciaria floribunda was also effective against this pest with LC 50 values (µg/insect) equal to 309.64 after one day of treatment, and 94.42 after 22 days of treatment.…”