Plant-Synthesized Nanoparticles: An Eco-Friendly Tool Against Mosquito Vectors?

Abstract

Mosquitoes (Diptera: Culicidae) are a key threat for millions of people worldwide, since they act as vectors for devastating parasites and pathogens. In this scenario, vector control is crucial. Mosquito larvae are usually targeted using organophosphates and insect growth regulators. Indoors residual spraying and insecticide-treated bed nets are also employed. However, these chemicals have strong negative effects on human health and the environment, and induce resistance in a number of vectors. Newer and safer tools have been recently implemented to enhance control of mosquitoes. Here I focus on characterization, effectiveness and non-target effects of mosquitocidal nanoparticles synthesized using botanical products (MNP). Currently, the majority of plant-fabricated MNP are silver ones; the biosynthesis exploits the reducing and stabilizing potential of extracts and metabolites from plants. The successful synthesis of MNP is usually confirmed by UV-visualization spectroscopy, followed by scanning electron microscopy (SEM) or transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDX), Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction studies (XRD). Interestingly, many plant-synthesized metal nanoparticles have been reported as effective larvicidals, pupicidals, adulticidals and oviposition deterrents against different mosquito species of medical and veterinary importance. Few parts per million of different MNP are highly toxic against the malaria vector Anopheles stephensi, the dengue vector Aedes aegypti and the filariasis mosquito Culex quiquefasciatus. However, despite the growing number of evidences about the effectiveness of MNP, little efforts have been carried out to shed light on their possible non-target effects against mosquito natural enemies and other aquatic organisms. In the final section, particular attention was dedicated to this issue. A number of hot areas that need further research and cooperation among parasitologists, entomologists and behavioral ecologists are highlighted.