Abstract
Lutzomyia longipalpis is the main vector of visceral leishmaniasis in Brazil. The objective was to evaluate the effect of oil from (Azadirachta indica) neem seeds on eggs, larvae and adults of the vector. The insects were captured in the field and kept in the laboratory at +/- 27 °C and 80% relative humidity. Five treatments with different concentrations were performed using two negative controls (distilled water and Tween 80) and a positive control. The eggs were sprayed with the oil at different concentrations and the number of hatched larvae evaluated for 10 days. Mortality of larvae was observed to pupation and adult mortality was observed after 24, 48, and 72 hours. Statistical analysis was performed by Tukey test at 5% probability. The highest oil concentration of eggs obtained 65.16 +/- 3.24% efficacy for reducing egg hatching. The test with larvae showed 67.75 +/- 2.21% efficacy at a concentration of 100 mg.mL⁻¹. In adults, the efficacy of the 100 mg.mL⁻¹ concentration was 96.64 +/- 4.11% after 24 hours. The phytochemical analysis revealed the presence of triterpenes. These results demonstrate the potential use of this oil in the control of this vector.
Highlights
Com a expansão da área de abrangência da doença e o aumento significativo do número de casos, a Leishmaniose Visceral (LV) passou a ser considerada pela Organização Mundial de Saúde uma das prioridades dentre as doenças tropicais (GONTIJO; MELO, 2004)
As estratégias de controle das doenças transmissíveis por vetores biológicos são complexas, principalmente quando associadas à existência de reservatórios domésticos e silvestres e aos aspectos ambientais
Na agricultura, muitas pesquisas têm sido realizadas, especialmente nas regiões tropicais, utilizando metabólitos secundários de plantas com a finalidade de proteger a colheita e armazenamento de grãos dos insetos
Summary
Os testes fitoquímicos do óleo para fenóis, taninos, esteroides, triterpenoides e alcaloides foram realizados seguindo a metodologia descrita por Matos (1997), que investigaram os tipos de metabólitos secundários presentes nos extratos de plantas. Estes se baseiam na adição de determinados reagentes à solução hidroalcoólica do óleo da planta e a observação das mudanças de cor e formação de precipitados. No teste para esteroides e triterpenóides (Lieberman-Burchard), foi adicionado 1 mL de anidrido acético e, em seguida, com agitação, três gotas de ácido sulfúrico (H2SO4) concentrado à solução de diclorometano do óleo. Coloração azul evanescente seguida de verde permanente é indicativa da presença de esteróides. Coloração parda até vermelha indica a presença de triterpenoides
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