Abstract
Botanical metabolites are increasingly realized as potential replacements to chemical insecticides. In the present study, Acacia nilotica seed essential oil and seed pod solvent extracts were tested for bioefficacy against three important types of mosquitoes. Mortality was recorded 24 h post-treatment, while smoke toxicity of adult mosquitoes was recorded at 10 min intervals for 40 min. Seed pod powder was extracted with different solvents and hydrodistilled seed oil chemical constituents were determined by using Gas chromatography mass spectroscopy (GC-MS) -. Larvicidal and adulticidal efficacy of seed hydrodistilled essential oil and solvent extracts were tested against larval and adult mosquitoes. The seed hydrodistilled oil provided strong larvicidal activity against Anopheles stephensi, (LC50 (lethal concentration that kills 50% of the exposed larvae) = 5.239, LC90 (lethal concentration that kills 90% of the exposed larvae) = 9.713 mg/L); Aedes aegypti, (LC50 = 3.174, LC90 = 11.739 mg/L); and Culex quinquefasciatus, (LC50 = 4.112, LC90 = 12.325 mg/L). Smoke toxicities were 82% in Cx. quinquefasciatus, 90% in Ae. aegypti, and 80% mortality in An. stephensi adults, whereas 100% mortality was recorded for commercial mosquito coil. The GC-MS profile of seed essential oil from A. nilotica showed the presence of hexadecane (18.440%) and heptacosane (15.914%), which are the main and active compounds, and which may be involved in insecticidal activity. Overall findings suggest that the seed oil showed strong mosquitocidal activity against mosquito vectors and therefore may provide an ecofriendly replacement to chemical insecticides.
Highlights
Mosquitoes are vectors of many tropical and subtropical pathogens that may cause severe health problems in countries where they are endemic [1]
The greatest larvicidal activity was observed in seed essential oil against An. stephensi, Ae. aegypti, and Cx. quinquefasciatus, with LC50 and LC90 values of 5.239–9.713, 3.174–11.739, and 4.112–12.325 mg/L, respectively (Tables 1–3)
Botanical oils isolated from several different species have shown strong larvicidal activities, for example, oils obtained from Ocimum gratissimum showed high larvicidal activity against An. stephensi (LC50 values 60 to 538 mg/L), and Lippie sidoides leaf extract showed notably high larvicidal activity against Ae. aegypti (LC50 : 67 mg/L) [40]
Summary
Mosquitoes are vectors of many tropical and subtropical pathogens that may cause severe health problems in countries where they are endemic [1]. Aedes aegypti and Ae. albopictus are primary carriers for viruses that cause dengue fever, dengue hemorrhagic fever, chikungunya fever, yellow fever, and Zika [2,3]. A vector of lymphatic filariasis, is widely distributed in tropical regions [4]. Lymphatic filariasis is possibly the most rapidly spreading mosquito vector-borne disease to humans in many part of the world and, worldwide, 146 million people suffer from lymphatic filariasis transmitted by. Res. Public Health 2018, 15, 388; doi:10.3390/ijerph15020388 www.mdpi.com/journal/ijerph
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