Larvicidal Potential of Fusarium oxysporum, Metarhizium anisopliae, and Trichoderma viride Silver Nanoparticles Against Mosquitoes (Diptera: Culicidae)
摘要
Aedes aegypti and Culex pipiens are critical in the epidemiology of various diseases due to their ability to transmit various disease causing pathogens. Fungi-based larvicides are a sustainable approach for controlling mosquitoes at their breeding sites. The present study determined the larvicidal efficacy of the Entomopathogenic fungus (EPF) and mycosynthesized silver nanoparticles (AgNPs) against fourth-instar larvae of Ae. aegypti and Cx. pipiens. These mycosynthesized AgNPs were fabricated by exploiting Fusarium oxysporum, Metarhizium anisopliae, and Trichoderma viride with AgNO3. The characterization of the synthesized dark brown nanoparticles were done by FTIR, SEM, and UV‒vis spectroscopy analysis. The conidial suspensions of the fungi as mentioned earlier were also prepared. Larvicidal bioassays were carried out using three concentrations of each conidial suspension and AgNPs against Ae. aegypti and Cx. pipiens. The results were obtained to ascertain the effectiveness of both treatments against the larvae of both mosquito species. Ae. aegypti and Cx. pipiens have shown gradual increase in mortality with increasing concentrations of mycosynthesized AgNPs. In larvicidal bioassays, some concentrations of mycosynthesized AgNPs resulted in complete mortality and no pupal or adult emergence. At 23 hours postexposure, some larvae became hyperactive and showed erratic swimming and loss of balance. Moribund or dead larvae were found after 510 hours. At the end of 24 hrs, almost all the larvae subsequently died with increasing concentrations of the mycosynthesized AgNPs. Thus, the larvicidal efficacy of three fungal conidial suspensions was comparable to that of their respective mycosynthesized AgNPs against fourthinstar larvae of both mosquito species. According to the LC50s and LC90s, FO- AgNPs are more lethal to Ae. aegypti and Cx. pipiens, respectively, as they show a consistent trend toward a high percentage of mortality. Hence, this eco-friendly strategy to control the Ae. aegypti and Cx. pipiens populations by deploying EPFs with AgNPs will help to control vectors that simultaneously decrease the burden of various diseases and improve environmental sustainability.