Acute toxicity and synergistic and antagonistic effects of the aromatic compounds of some essential oils against Culex quinquefasciatus Say larvae

Abstract

The efficacy of 30 aromatic compounds and their mutual binary combinations was assessed for acute toxicity against the larvae Culex quinquefasciatus. Based on comparison of the lethal doses, thymol and p-cymene were selected as the most effective (LD50 = 18 and 21 mg L(-1), respectively, and LD90 = 25 and 30 mg L(-1), respectively). Although the LD50 for terpinolene and trans-anethole was also estimated at 21 mg L(-1), their LD90 was significantly higher compared to the substances above (245 and 34 mg L(-1), respectively). In total, 435 binary combinations were tested, of which 249 combinations showed a significant synergistic effect, while 74 combinations showed a significant antagonistic effect on mortality. Only nine substances were identified as being able to create a synergistic effect with more than 20 substances: limonene, trans-anethole, 4-allylanisole, carvacrol, isoeugenol, menthone, carvone, borneol, and camphor. The highest synergistic effect on larval mortality was achieved for the combinations: eugenol and isoeugenol, carvone and carvacrol, carvone and 4-allylanisole, carvone and α-terpineol, carvone and menthone, limonene and trans-anethole, limonene and menthone, α-pinene and menthone, β-citronellol and menthone, carvacrol and 4-allylanisole, carvacrol and terpineol, α-terpinene and trans-anethole, camphor and menthone, camphene and menthone, and 4-allylanisole and menthone. Significant differences between achieved mortality and the mutual mixing ratio were found for the five selected binary mixtures that had shown the most significant synergistic effect in the previous tests. The mixture of limonene and trans-anethole showed the highest mortality, with the mixing ratio 1:1; the mixture of eugenol and isoeugenol caused 90.2% mortality, with the mixing ratio 1:3. One hundred percent mortality was achieved if carvacrol was contained in a mixture with carvone in a ratio >2. After a comparison of all our results, based on our experiments, we can choose two pairs that caused mortality higher than 90% in concentrations lower than 20 mg L(-1): limonene and trans-anethole (with the mixing ratio 1:1), and carvone and carvacrol (with the mixing ratio 1:2-3). The information gained can thus be used in the development of new botanical insecticides based on essential oils (EOs) and particularly in the creation of formulations.

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

“…Screening botanicals for their mosquitocidal potential may offer effective and eco-friendly tools in the fight against mosquitoes (Pavela 2015b;Benelli 2016c;Benelli and Mehlhorn 2016). In this study, the EO extracted from the medicinal plant O. scabrum was analyzed by GC-MS and evaluated for its mosquitocidal and repellent potential towards A. stephensi, A. aegypti, C. quinquefasciatus, and C. tritaeniorhynchus.…”

“…Plant-borne insecticides, as well as essential oils (EOs), are encouraging since they are effective at reduced doses, environmental-friendly, biodegradable, and often economical (Benelli 2015b;Pavela 2015a;Govindarajan and Benelli 2016a, b, c;Govindarajan et al 2011Govindarajan et al , 2013a. Thus, recent research focused on plant EOs and extracts as possible sources of arthropod ovicidal, larvicidal, adulticidal, and repellent compounds (e.g., Cheng et al 2003Cheng et al , 2004Govindarajan 2010a;Govindarajan et al 2011;Dinesh et al 2015;Madhiyazhagan et al 2015;Murugan et al 2015a, b, c;Pavela 2015b;Suresh et al 2015;Benelli et al 2016b;Jaganathan et al 2016;Panneerselvam et al 2016).…”

Antifeedant effects of common terpenes from Mediterranean aromatic plants on Leptinotarsa decemlineata

“…Culex quinquefasciatus Say has also been observed (Pavela, 2015). Consequently, these aspects should be considered by agrochemical industry when developing commercial biopesticides.…”

Effects of Artemisia herba-alba essential oils on survival stored cereal pests: Tribolium castaneum (Herbst) (Coleoptera, Tenebrionidae) and Trogoderma granarium (Everst) (Coleoptera, Dermestidae)

“…Chemical control using conventional insecticides with serious drawbacks are considered as unfriendly to the environment. These problems lead to increasingly stringent environmental regulation of pesticides [5,6]. The essential oils are being assessed as potential candidates for pests and disease management.…”