Ovicidal, pupicidal, adulticidal, and repellent activity of Helicteres velutina K. Schum against Aedes aegypti L. (Diptera: Culicidae)

Abstract

Aedes aegypti is a vector of emerging and neglected diseases, such as dengue, chikungunya, and Zika. Helicteres velutina, known as "pitó" in Brazil, is traditionally used as an insect repellent, and several studies have demonstrated its larvicidal activity. The aim of this study was to investigate this species and evaluate its potential ovicidal, pupicidal, adulticidal, and repellent activity. The viability of the eggs was evaluated using different concentrations of the test substances for 25 days. The hexane fraction killed 72.7% of the eggs, while dichloromethane killed 67.7%. The survival of the pupae and adults was verified after 72 h and 48 h, respectively. The LC 50 for the hexane and dichloromethane fractions was 0.12 mg/mL and 8.85 mg/mL for pupae, 8.01 mg/mL and 0.74 mg/mL for adults (tarsal test), and 0.05 mg/mL and 0.23 mg/mL for adults (body test), respectively. Repellency was assessed for 240 min using neonatal Wistar rats on a Y-tube olfactometer. The hexane fraction attracted mosquitoes to the test chamber, while the dichloromethane fraction had a repellent action. The 7,4'-di-O-methyl-8-O-sulfate flavone provides greater repellency, and this finding is similar to the results of the in silico studies that have shown the potential of this substance against adult mosquitoes. This suggests that 7,4'-di-O-methyl-8-O-sulfate flavone may be one of the substances present in the extract from aerial parts of H. velutina that is responsible for the repellent activity mentioned in traditional medicine. These findings provide a better understanding of the insecticidal and repellent activity of the extract, fraction, and compounds isolated from H. velutina against Ae. aegypti, thereby revealing its potential in the development of a more effective botanical insecticide.

Enhanced Antimicrobial, Cytotoxicity, Larvicidal, and Repellence Activities of Brown Algae, Cystoseira crinita-Mediated Green Synthesis of Magnesium Oxide Nanoparticles

“…Repellents are chemicals that prohibit arthropods from landing on the skin and thus prevent bites and the resulting disease transmission ( Tavares et al, 2018 ). Although synthetic insecticides and repellents are easy to use and fast-acting, their continued use disrupts the ecological balance and the consequent damage to nontarget organisms, as well as the development of insect resistance, in addition to the cost of these chemicals limiting their use in low-income countries ( Fernandes et al, 2021 ). As research continues to create economical and environmentally safe alternatives that have insecticidal properties, in this research, we explored the properties of phyco-synthesized MgO-NPs as insect repellent.…”

Extratos aquosos de Psychotria sp. interferem na biologia de Plutella xylostella

“…Os extratos botânicos com propriedades inseticidas buscam minimizar esses problemas, pois não são letais para uma variedade de indivíduos não-alvo. Dependendo da concentração utilizada e do método de extração, certos extratos podem provocar diversas reações sobre os insetos-daninhos, como inibição da alimentação e da oviposição (Prakash & Rao, 1997;Miresmailli & Isman, 2014), redução da fecundidade (Peres et al 2017;Ferreira et al 2020), repelência (Boiça Jr. 2013, alterações morfológicas e fisiológicas (Ribeiro et al 2016;Peres et al 2017), toxicidade sobre larvas, pupas e ovos (Risco et al, 2012;Liu et al, 2019;Fernandes et al, 2021) e infertilidade em adultos (Santiago et al, 2008).…”