Dados do Trabalho

Título

Toxicity of the essential oil from Piper alatipetiolatum (Piperaceae) against Culex quinquefasciatus larvae (Diptera: Culicidae)

Introdução

Culex quinquefasciatus (Culicidae) is the primary vector of lymphatic filariasis, commonly known as elephantiasis, in Brazil. The growing resistance of this mosquito to commercial insecticides presents a significant challenge for both vector and disease control. In response to this issue, essential oils (EOs) extracted from plants have emerged as promising agents against Culex species, providing a viable biotechnological alternative. 

Objetivo (s)

This study aimed to investigate the toxicity and mechanism of action of the EO from P. alatipetiolatum against C. quinquefasciatus larvae, with a particular focus on oxidative stress.

Material e Métodos

The EO was extracted from P. alatipetiolatum leaves (200 g) using hydrodistillation, and subsequently analysed using GC-MS and GC-FID. Larvicidal activity was evaluated at concentrations ranging from 2.5 to 30 µg/mL against C. quinquefasciatus larvae (3rd instar), following WHO guidelines for larvicidal tests. DMSO (1%) and α-cypermethrin (0.14 µg/mL) were used as negative and positive controls, respectively. Reactive oxygen and nitrogen species (RONS), catalase (CAT), glutathione S-transferase (GST), acetylcholinesterase (AChE), and thiol levels were used as indicators of oxidative stress. GC-MS and GC-FID analyses revealed that the EO was rich in sesquiterpenes, with ishwarone being the major compound (78.6%). 

Resultados e Conclusão

Furthermore, the EO demonstrated significant larvicidal activity (CL50 of 4.53 μg/mL), compared to α-cypermethrin (CL50 of 0.14 μg/mL). This activity was accompanied by an increase in RONS production and alterations in CAT, GST, AChE, and thiol levels compared to control groups (p < 0.05), suggesting that the mechanism of action of the EO occurs through the induction of oxidative stress in treated larvae. Thus, the EO from P. alatipetiolatum appears to be a promising larvicidal agent for controlling C. quinquefasciatus larvae.

Palavras Chave

Culex; botanical larvicidal; oxidative stress.