A Global Systematic Review on the Potential of Metal-Based Nanoparticles in the Fight Against Mosquito Vectors

Background: Mosquito-borne diseases, such as malaria, filariasis, dengue, chikungunya, Zika, and other viral infections, pose significant public health challenges worldwide. For many years, chemical insecticides were used in the form of indoor residual spraying (IRS) and insecticide-treated nets (ITNs). However, these methods have encountered several limitations such as the development of resistance, environmental impact, and nontarget effects. In recent years, metal-based nanoparticles (MNPs) have emerged as a promising alternative in the fight against mosquito vectors. This systematic review aimed to explore the potential application of MNPs in combating medically significant vectors. Methods: Global databases such as PubMed, Scopus, Web of Science, and ProQuest were used to search for relevant articles published from 2011 to 2021. The data search was conducted between July 30 and August 15, 2022. Keywords such as "Metal-based nanoparticles," "Nanoparticles toxicity," "Mosquito control," "Larvicidal," "Nanomaterials in mosquito control," and "biosynthesized" were used both individually and in combination to find pertinent studies. Only original articles published in English that offered comprehensive information on the effects of biosynthesized MNPs on mosquitoes were included in the study. These articles were selected based on the presence of key details such as the type and source of nanoparticles (NPs), size range (1-100 nm), and the mosquito larval species tested, exposure duration, and corresponding lethal concentration (LC) levels. Studies lacking sufficient data or with unavailable full texts were excluded from the analysis. The quality of each original article was evaluated using a standardized quality assessment tool adapted from the Joanna Briggs Institute (JBI) Critical Appraisal Checklist. Data were extracted from texts, tables, and figures of the included articles, and their validity was assessed using standardized tools. Result: A total of 65 articles were included, covering laboratory and field findings on NPs such as silver (Ag), gold (Au), palladium (Pd), cobalt (Co), titanium dioxide (TiO₂), nickel (Ni), copper (Cu), cadmium (Cd), selenium (Se), zinc (Zn), magnesium oxide (MgO), iron and iron oxide (Fe and Fe₂O₃), and aluminum oxide (Al₂O₃). Among these, AgNPs and CuNPs were the most extensively tested and found effective against various larval instars, pupae, and adults of Aedes aegypti, Ae. albopictus, Anopheles stephensi, An. subpictus, Culex quinquefasciatus, and Cx. pipiens, with satisfactory 50% and 90% LC values. Conclusions: The study highlighted the promising potential of MNPs as effective agents for controlling mosquito vectors, particularly at various developmental stages of Anopheles, Culex, and Aedes species. Most studies focused on AgNPs and AuNPs, with some attention given to other MNPs. Notably, NPs synthesized from plant extracts such as Azadirachta indica and microorganisms demonstrated strong larvicidal activity, especially against Culex, Anopheles, and Aedes larvae. Efficacy varied across developmental stages, with first-, third-, and fourth-instar larvae being most susceptible. These findings underscore the potential of MNPs as an environmentally friendly alternative to conventional mosquito control methods. Implications of Key Findings: MNPs, especially Ag and AuNPs, are effective larvicides targeting the early developmental stages of mosquitoes. These NPs, derived from plants and microorganisms, demonstrate an environmentally friendly, cost-effective insecticidal effect and could serve as alternatives to chemical insecticides. However, further research is needed to optimize their synthesis, application, and scalability for large-scale use. Additionally, the varying efficacy of different mosquito species and life stages requires a more targeted, species-specific use of NPs, along with ongoing environmental assessments to ensure their long-term safety and effectiveness.