An Experimental Evaluation of Toxicity Effects of Sodium Chloride on Oviposition, Hatching and Larval Development of Aedes albopictus

Abstract

Dengue virus, one of the most important mosquito-borne viruses, has shown a sharp upward trend, spreading around the world in recent years. Control of vectors Aedes aegypti and Ae. albopictus remains crucial for blocking dengue transmission. The lethal ovitrap (LO) is one of the cost-effective traps based on the classic “lure and kill” strategy, and finding a proper long-lasting effective toxin is key to achieving the desired effect. The concentration of inorganic salts of habitat environment plays a strong role in affecting oviposition, hatching, and development of mosquitoes, but the potential insecticide activity of Sodium Chloride (NaCl) in habitat water as well as LO still lacks research. In this study, we carried out laboratory experiments to systematically explore the effects of different concentrations of NaCl solutions on oviposition, egg hatching, and larval development of Ae. albopictus. Consequently, Ae. albopictus was found to prefer freshwater to lay eggs; whereas 48.8 ± 2.6% eggs were laid in freshwater and 20% in ≥1.0% brackish water, few eggs were laid in 3.0% NaCl solution. Compared with egg hatching, larval development of Ae. albopictus presented a higher sensibility to NaCl concentration. The mortality of the 3rd–4th larvae in 1.0% NaCl solution was 83.8 ± 8.7%, while in 3.0% it reached 100%. Considering the cumulative effect of NaCl, when NaCl concentration was ≥1.0%, no eggs could successfully develop into adults. These data suggested that NaCl solutions with a concentration ≥1.0% can be used as an effective cheap insecticide for Ae. albopictus in subtropical inland aquatic habitats, and also as the “kill” toxin in LOs. Meanwhile, the concentration range from 0 to 2.0% of NaCl solution has the potential to be used as the “lure” in LOs. The technological processes of how to use NaCl as insecticide or in LOs still needs further in-depth exploration.

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

“…The acute toxicity of sodium chloride to rst and fourth instar Aedes albopictus larvae and concluded that Ae. albopictus rst instar larvae were more susceptible to NaCl than fourth instar(Jinguji et al 2021) but our results indicated that the 3rd-4th instar larvae could be more susceptible to NaCl concentrations, possibly as a result of cumulative toxicity brought on by prolonged exposure to the Sodium Chloride solution which is at par with the recent studies conducted at China(Guo et al 2022). Our experiments showed that in 24 hours, LC50 and LC90 of NaCl concentration on 3rd-4th instar larvae was 2.27 and 1.32% respectively which is similar to previous studies(Jinguji et al 2021).…”

“…Plethora of scienti c reports has shown that concentration of inorganic salts in an environmental habitat has a signi cant impact on oviposition, hatching and development of mosquitoes which in turn in uence their abundance and distribution (Guo et al 2022). In this regard, most common inorganic salt i.e., Sodium Chloride (NaCl) in aquatic habitats is worth being explored.…”