An Experimental evaluation of acute toxicity of Sodium Chloride against Aedes aegypti (Linnaeus) larvae

Abstract

The prevalence of dengue, one of the most important mosquito-borne diseases, has increased more than eight-fold during the past two decades. The primary and most prevalent mosquito vector, Aedes aegypti L., is responsible for spreading viruses that cause dengue and other harmful diseases. Control of vectors is of particular concern to block dengue transmission. Different chemical measures used for vector control caused various environmental issues, mosquito resistance, resurgence, harmful impacts on non-target organisms increased attention towards cost-effective and environment-friendly control measures. Hence, the present study aimed to check the larvicidal potential of Sodium Chloride (NaCl) and examined its acute toxicity against 4th instar larvae of Ae. aegypti.Acute toxicity tests were conducted as per WHO guidelines. Different NaCl concentrations i.e., 0.5%, 1.0%, 1.5%, 2.0%, 2.5% and 3.0% were prepared using pure NaCl along with distilled water. Larvicidal activity was assessed and toxicity values were computed using Log-Probit Method. Several morphological and behavioral alterations in treated Ae. aegypti larvae were also observed. Sixty percent larvae of Ae. aegypti died after exposing to 1.5% NaCl concentrations within 48 hours and larval mortality significantly increased up to ninety-seven and hundred percent after treatment with more than 2% NaCl solution within 24 and 48 hours respectively. Various ruptures were observed in abdomen and anal papillae along with abnormal behaviour in the treated larvae. Our study concluded that Sodium Chloride can be used as an effective and safe intervention in mosquito control programmes due to its easy availability and less toxicity.