Seagrasses as sources of mosquito Nano-Larvicides? Toxicity and uptake of Halodule uninervis-biofabricated silver nanoparticles in Dengue and Zika Virus vector Aedes aegypti

Mosquitoes (Diptera: Culicidae) act as vectors for devastating pathogens and parasites. Zika virus, an Aedes mosquito-borne flavivirus, is becoming a worldwide public health concern following its suspected association with over 4000 recent cases of microcephaly in the infants of some women who were pregnant when they contracted the disease. There are no specific treatments for Zika virus, thus the eco-friendly and effective control of mosquito vectors is crucial. This research proposed a novel method of seagrass-mediated synthesis of silver nanoparticles (AgNP) using Halodule uninervis as a reducing and capping agent. UV–Vis spectroscopy, FTIR spectroscopy, SEM, EDX spectroscopy, XRD and Raman analysis confirmed the rapid and cheap synthesis of AgNP. LC50of H. uninervis extract against Aedes aegypti was 295.629 ppm and LC50of H. uninervis-synthesized AgNP was 12.554 ppm. Microscopy analysis pointed out the uptake of H. uninervis-fabricated AgNP in the midgut of mosquito larvae. In MIC assays, low doses of the AgNP inhibited the growth of Bacillus subtilis, Klebsiella pneumoniae and Salmonella typhi. Overall, this research shed light on the mosquitocidal potential of H. uninervis, as a bio-resource for the cheap and effective nanosynthesis of mosquitocidal biopesticides.