Acute toxicity and repellent activity of the Origanum scabrum Boiss. & Heldr. (Lamiaceae) essential oil against four mosquito vectors of public health importance and its biosafety on non-target aquatic organisms

Abstract

The recent outbreaks of dengue, chikungunya, and Zika virus highlighted the pivotal importance of mosquito vector control in tropical and subtropical areas worldwide. However, mosquito control is facing hot challenges, mainly due to the rapid development of pesticide resistance in Culicidae and the limited success of biocontrol programs on Aedes mosquitoes. In this framework, screening botanicals for their mosquitocidal potential may offer effective and ecofriendly tools in the fight against mosquitoes. In the present study, the essential oil (EO) obtained from the medicinal plant Origanum scabrum was analyzed by GC-MS and evaluated for its mosquitocidal and repellent activities towards Anopheles stephensi, Aedes aegypti, Culex quinquefasciatus, and Culex tritaeniorhynchus. GC-MS analysis showed a total of 28 compounds, representing 97.1 % of the EO. The major constituents were carvacrol (48.2 %) and thymol (16.6 %). The EO was toxic effect to the A. stephensi, A. aegypti, C. quinquefasciatus, and C. tritaeniorhynchus larvae, with LC 50 of 61.65, 67.13, 72.45, and 78.87 μg/ml, respectively.Complete ovicidal activity was observed at 160, 200, 240, and 280 μg/ml, respectively. Against adult mosquitoes, LD 50 were 122.38, 134.39, 144.53, and 158.87 μg/ml, respectively. In repellency assays, the EOs tested at 1.0, 2.5, and 5.0 mg/cm 2 concentration of O. scabrum gave 100 % protection from mosquito bites up to 210, 180, 150, and 120 min, respectively. From an eco-toxicological point of view, the EO was tested on three non-target mosquito predators, Gambusia affinis, Diplonychus indicus, and Anisops bouvieri, with LC 50 ranging from 4162 to 12,425 μg/ml. Overall, the EO from O. scabrum may be considered as a low-cost and eco-friendly source of phytochemicals to develop novel repellents against Culicidae.

Chemical composition and insecticidal potential of different Origanum spp. (Lamiaceae) essential oils against four stored product pests

“…Different activities of Origanum spp. such as antioxidant (Dutra et al, 2019), cytotoxic (Coccimiglio et al, 2016), antimicrobial (Lesjak et al, 2016;Reyes-Jurado et al, 2019), anti-acetylcholinesterase (Abou-Taleb et al, 2016;Hajlaoui et al, 2016;López et al, 2018), antibacterial (da Cunha et al, 2018;Wijesundara & Rupasinghe, 2018), repellent (Govindarajan et al, 2016;La Pergola et al, 2017;Giatropoulos et al, 2018), antifungal (Vinciguerra et al, 2018), allelopathic (Boukaew et al, 2017), phytotoxic (Ibáñez & Blázquez, 2018;Grul'ová et al, 2019) insecticidal (Kim et al, 2016;Szczepanik et al, 2018;Benelli et al, 2019) have been determined in a number of studies.…”

Larvicidal Activity of Essential Oils From Piper Species Against Strains of Aedes aegypti (Diptera: Culicidae) Resistant to Pyrethroids

“…Studies focusing on the investigation of EOs from plants from the perspective of discovering new ovicides, larvicides, adulticides and repellents have been an important strategy for controlling agricultural pests, vectors of medical-veterinary importance or urban viruses (Santos et al, 2012;Phukerd and Soonwera, 2014;Govindarajan et al, 2016;Benelli et al, 2017;Muturi et al, 2017;Luz et al, 2020a). Regarding the urban diseases in tropical regions, A. aegypti is considered one of the main targets since it has great dispersal capacity, is the vector of DENV, ZIKV, CHIKV viruses, and has developed a remarkable resistance to commercially available insecticides (Smith et al, 2016).…”

Prevention and Control Strategies to Counter Zika Virus, a Special Focus on Intervention Approaches against Vector Mosquitoes—Current Updates

“…quinquefasciatus (LC 50 of 72.45 ppm), and Cx. tritaeniorhynchus (LC 50 of 78.87 ppm) (Govindarajan et al, 2016a ). Similarly, the essential oil also had ovicidal activity against An.…”

“…tritaeniorhynchus up to 210, 180, 150, and 120 min, respectively. This essential oil was found less toxic to non-mosquito predators like Anisops bouvieri, Gambusia affinis , and Diplonychus indicus with LC 50 range of 4,162 to 12,425 ppm (Govindarajan et al, 2016a ). Essential oils from other herbs, such as Heracleum sprengelianum , have also been studied for their larvicidal activity, revealing effectiveness against Ae.…”