The Aedes albopictus mosquito is an arthropod that belongs to the Culicidae family and is known as the Asian tiger mosquito. It is considered the second most important arbovirus vector in the world. For its part, the Aedes albopictus species has a high incidence in Brazil and in recent times France has seen a high level of proliferation of this vector, due to climate change. Prevention therefore depends on vector control and one strategy is the use of larvicides based on essential oils, which have a low resistance rate compared to the chemical insecticides that are currently the main control strategy. The essential oil extracted from the leaves of Lippia gracilis, a species native to the Caatinga and Cerrado, popularly known as rosemary of the serrote or chapada, has a high oil yield, with carvacrol and thymol being the main compounds, both substances having proven larvicidal potential in arbovirus vectors. The aim of this study was to investigate the insecticidal activity of Lippia gracilis' essential oil (EO) on Ae. albopictus, as well as the possible mechanisms involved. For this purpose, larvae from the colony of the Laboratory of Biotechnology Applied to Parasites and Vectors were used. Eggs were used for ovicidal activity (n=30), in larvicidal activity, groups of larvae L3 (n=25) and for pupicidal activity we used pupae (n=25) that were exposed to different concentrations of EO (2.5-80 ppm). Egg hatching was assessed after 15 days and larval and pupal mortality after 24 hours. The tests were carried out in duplicate for larvicidal activity and in triplicate for ovicidal and pupicidal activity. To analyze the larval cell profile and measure nitric oxide (NO) production, hemolymph was collected from larvae exposed to the LC50 obtained after 24 h. The total cell profile was analyzed using a Neubauer chamber. NO was measured using the Griess method in a spectrophotometer (546 nm). The total cell profile was analyzed using a Neubauer chamber Statistical analysis used GraphPad Prism 8.0 (p<0.05). It was observed that the ovicidal activity inhibited (100%) hatching at 60 ppm, larvicidal activity (100%) was obtained from 60 ppm, with this the (LC50 =33.18 ppm) and pupicidal activity had (100%) mortality from 80 ppm. In the NO dosage, an 88% decrease in production was observed in the hemolymph of Ae. albopictus larvae after exposure. EO caused a 51% reduction in total cellularity in Ae. albopictus compared to the control. Therefore, the EO of L. gracilis can be considered an effective method of control against the vectors responsible for transmitting arboviruses such as dengue, chikungunya, zika and yellow fever, as well as being a natural biotechnological product and having high efficiency in obtaining the oil, making the cost low for production, thus helping to reduce the use of chemical and synthetic substances that cause resistance and harm the environment and humans.
Comissão Organizadora
Francisco Mendonça Junior
Pascal Marchand
Teresinha Gonçalves da Silva
Isabelle Orliac-Garnier
Gerd Bruno da Rocha
Comissão Científica
Ricardo Olimpio de Moura
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