Bioactivity of Different Chemotypes of Oregano Essential Oil against the Blowfly Calliphora vomitoria Vector of Foodborne Pathogens

Abstract

Blowflies play a substantial role as vectors of microorganisms, including human pathogens. The control of these insect pests is an important aspect of the prevention of foodborne diseases, which represent a significant public health threat worldwide. Among aromatic plants, spices essential oils (EOs) are the most suitable to protect food from insect pests. In this study, we determined the chemical composition of three oregano EOs and assessed their toxicity and deterrence to oviposition against the blowfly Calliphora vomitoria L. The chemical analyses showed that the EOs belonged to three chemotypes: one with a prevalence of carvacrol, the carvacrol chemotype (CC; carvacrol, 81.5%), and two with a prevalence of thymol, the thymol/p-cymene and thymol/γ-terpinene chemotypes (TCC and TTC; thymol, 43.8, and 36.7%, respectively). The bioassays showed that although all the three EOs chemotypes are able to exert a toxic activity against C. vomitoria adults (LD50 from 0.14 to 0.31 μL insect−1) and eggs (LC50 from 0.008 to 0.038 μL cm−2) as well as deter the oviposition (Oviposition Activity Index, OAI, from 0.40 ± 0.04 to 0.87 ± 0.02), the bioactivity of oregano EOs significantly varies among the chemotypes, with the thymol-rich EOs (TCC and TTC) overall demonstrating more effectiveness than the carvacrol-rich (CC) EO.

Variability of the Chemical Composition of the Essential Oil from the Amazonian Ishpingo Species (Ocotea quixos)

“…The shade level (shading) exerted a marked influence on the percentage of main compounds 15, 18, and 21 [ 15 ]; among all samples (Q11–Q15), a statistically significant difference was determined ( p -value < 0.5). Differentiating main compounds in essential oil samples of the same species results in the so-called essential oil chemotypes [ 16 ]. According to Figure 1 , the different environmental conditions produced two chemotypes in the essential oil of the O. quixos (E)-methyl cinnamate chemotype and trans-Caryophyllene and (E)-cinnamyl acetate chemotype.…”

Systematic Phytochemical Screening of Different Organs of Calotropis procera and the Ovicidal Effect of Their Extracts to the Foodstuff Pest Cadra cautella

“…C. cautella eggs mortalities were reported as a mean ± standard error (ES). Mortality was adjusted for the natural mortality of eggs [49] according to the following formula: Adjusted mortality (%) = 100 × (X−Y)/(100−Y), where X is the percentage mortality of the treated sample, and Y is the percentage mortality of the untreated control sample. Means were compared via one-way ANOVA with the extractant (latex extracts) or plant organ (plant extracts) as fixed factors.…”

Andean Plants Essential Oils: A Scented Alternative to Synthetic Insecticides for the Control of Blowflies

“…A safer and more sustainable alternative to the use of synthetic insecticides for the control of blowflies are essential oils (EOs) [16,[25][26][27][28]. Although the effectiveness of several EOs was widely proven, they are not so widely applied yet, as it would be expected in real life.…”

“…One of the reasons for such limited use is certainly their distinctive odour. In previous works, we tested the susceptibility of Calliphora vomitoria (L.) (Diptera: Calliphoridae) to the toxic activity of several EOs distilled from aromatic plants traditionally used as culinary herbs [25,27,28]. The EO from Allium sativum L. (Amaryllidaceae) was the most effective one, and it was successfully used as a component of an emulsion, which was sprayed as a mist to build an olfactory barrier and discourage blowflies from entering a meat-processing room of a ham-curing factory [27].…”