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Mosquitoes are responsible for the transmission of many pathogens and parasites, which cause serious diseases in humans and animals. Currently, botanical products have been suggested as alternative tools in the fight against arthropod vectors. In this study, the essential oil (EO) extracted from Zingiber cernuum was tested as larvicide and oviposition deterrent on six mosquito species of public health relevance, including malaria and Zika virus vectors. The EO showed high toxicity on third instar larvae of Anopheles stephensi (LC50 = 41.34 μg/ml), Aedes aegypti (LC50 = 44.88 μg/ml), Culex quinquefasciatus (LC50 = 48.44 μg/ml), Anopheles subpictus (LC50 = 51.42 μg/ml), Aedes albopictus (LC50 = 55.84 μg/ml), and Culex tritaeniorhynchus (LC50 = 60.20 μg/ml). In addition, low doses of Z. cernuum EO reduced oviposition rates in six mosquito species. The acute toxicity of Z. cernuum EO on four mosquito predators was scarce; LC50 ranged from 3119 to 11,233 μg/ml. Overall, our results revealed that the Z. cernuum EO can be considered for the development of effective and environmental-friendly mosquito larvicides and oviposition deterrents. [ABSTRACT FROM AUTHOR]

A wide number of studies dealing with mosquito control focus on toxicity screenings of whole plant essential oils, while limited efforts shed light on main molecules responsible of toxicity, as well as their mechanisms of action on non-target organisms. In this study, GC-MS shed light on main essential oil components extracted from leaves of the Suriname cherry Eugenia uniflora, i.e., curzerene (35.7%), trans-β-elemenone (11.5%), and γ-elemene (13.6%), testing them on Anopheles subpictus, Aedes albopictus, and Culex tritaeniorhynchus larvae. Non-target toxicity experiments were carried out on four species of aquatic larvivorous organisms, including fishes, backswimmers, and waterbugs. The essential oil from E. uniflora leaves tested on An. subpictus, Ae. Albopictus, and Cx. tritaeniorhynchus showed LC50 of 31.08, 33.50, and 36.35 μg/ml, respectively. Curzerene, trans-β-elemenone, and γ-elemene were extremely toxic to An. subpictus (LC50 = 4.14, 6.13, and 10.53 μg/ml), Ae. albopictus (LC50 = 4.57, 6.74, and 11.29 μg/ml), and Cx. tritaeniorhynchus (LC50 = 5.01, 7.32, and 12.18 μg/ml). The essential oil from E. uniflora leaves, curzerene, trans-β-elemenone, and γ-elemene showed low toxicity to larvivorous fishes, backswimmers, and waterbugs, with LC50 ranging from 303.77 to 6765.56 μg/ml. Predator safety factor (PSF) ranged from 55.72 to 273.45. Overall, we believe that curzerene isolated from the essential oil from E. uniflora leaves can represent an ideal molecule to formulate novel mosquito larvicides, due to its extremely low LC50 on all tested mosquito vectors (4.14-5.01 μg/ml), which far encompasses most of the botanical pesticides tested till now. Notably, the above-mentioned LC50 did not damage the four aquatic predators tested in this study. [ABSTRACT FROM AUTHOR]

The use of synthetic pesticides to control vector populations is detrimental to human health and the environment and may lead to the development of resistant strains. Plants can be alternative sources of safer compounds effective on mosquito vectors. In this study, the mosquito larvicidal activity of Boswellia ovalifoliolata leaf essential oil (EO) was evaluated against Anopheles stephensi, Anopheles subpictus, Aedes aegypti, Aedes albopictus, Culex quinquefasciatus, and Culex tritaeniorhynchus. GC-MS revealed that the B. ovalifoliolata EO contained at least 20 compounds. The main constituents were β-pinene, α-terpineol, and caryophyllene. In acute toxicity assays, the EO was toxic to larvae of An. stephensi, Ae. aegypti, Cx. quinquefasciatus, An. subpictus, Ae. albopictus, and Cx. tritaeniorhynchus with LC50 values of 61.84, 66.24, 72.47, 82.26, 89.80, and 97.95 μg/ml, respectively. B. ovalifoliolata EO was scarcely toxic to mosquito fishes, backswimmers, and water bugs predating mosquito larvae with LC50 from 4186 to 14,783 μg/ml. Overall, these results contribute to develop effective and affordable instruments to magnify the reliability of Culicidae control programs. [ABSTRACT FROM AUTHOR]

Essential oils (EOs) from plants may be alternative sources of molecules toxic against mosquito vectors of public health relevance. Most of researches in this field focused on EOs as larvicides or ovicides, while limited efforts focused on the exploitation of EOs as oviposition deterrents. In the present study, the larvicidal and oviposition deterrent activity of Syzygium lanceolatum leaf EO was evaluated against six mosquito species, Anopheles stephensi, An. subpictus, Aedes aegypti, Ae. albopictus, Culex quinquefasciatus, and Cx. tritaeniorhynchus. The chemical composition of the S. lanceolatum EO was analyzed by GC-MS analysis, showing the presence of phenyl propanal, β-caryophyllene, α-humulene, and caryophyllene oxide as major constituents. S. lanceolatum EO showed high acute toxicity on An. stephensi (LC50 = 51.20 μg/ml), Ae. aegypti (LC50 = 55.11 μg/ml), Cx. quinquefasciatus (LC50 = 60.01 μg/ml), An. subpictus (LC50 = 61.34 μg/ml), Ae. albopictus (LC50 = 66.71 μg/ml), and Cx. tritaeniorhynchus (LC50 = 72.24 μg/ml) larvae. Furthermore, the EO was effective as oviposition deterrent against the six tested mosquito species, with OAI on An. stephensi, An. subpictus, Ae. aegypti, Ae. albopictus, Cx. quinquefasciatus, and Cx. tritaeniorhynchus reaching −0.83, −0.81, −0.84, −0.83, −0.84, and −0.86, respectively. The toxicity of S. lanceolatum EO against several biological control agents of mosquitoes, including water bugs (Anisops bouvieri and Diplonychus indicus) and fishes (Gambusia affinis and Poecilia reticulata), was extremely low, with LC50 ranging between 4148 and 15,762 μg/ml. Overall, our results pointed out the promising potential of the S. lanceolatum leaf EO as a source of environmental-friendly oviposition deterrents and larvicides effective against a wide number of mosquito species of importance for parasitology. [ABSTRACT FROM AUTHOR]