Synthesis of bimetallic nanoparticles has employed many applications especially as larvicidal agents, these bimetallic nanoparticles therefore need to be produced via a cost-effective and eco-friendly route. Here, green synthesis of Ag-Co hybrid nanoparticles obtained from aqueous root extract of palmyra palm was reported. The hybrid nanoparticles formation was noticed by a colour change from light pink to light brown and further studied using UV-Vis and FT-IR spectrophotometers. The maximum absorption wavelength, λ max as determined by the UV-Visible Spectrophotometer was found to be 420 nm. The FT-IR showed the formation and stabilization of the BMNPs. The nanolarvicidal potency was evaluated by the application of varying concentration ranging from 5 to 50 mg/L against first to fourth instars of larvae and recording the percentage mortality after 24 hours. Probit analysis showed the LC 50 and LC 90 for 1 st instar to be 5.237 mg/L and 49.240 mg/L, 9.310 mg/L and 94.969 mg/L for 2 nd instar, 13.626 mg/L and 105.542 mg/L for 3 rd /4 th instars respectively. This result therefore suggests that the nanoparticles can be used as potential control for larval population growth.

Article History KeywordsGreen synthesis Cu/Ni BMNPs Palmyra palm Fruit extract Larvicidal activity Culex quinquefasciatus.The mixture of Cu 2+ /Ni 2+ solution was reduced to Cu/Ni BMNPs using fruit extract of Palmyra palm as a green reducing agent. The formation of Cu/Ni BMNPs noticed based on the visual change in color of the reaction mixture at room temperature from sky-blue to light blue within 15 min. UV-Visible and Fourier Transform Infra Red spectrophotometers were applied to investigate the Optical properties as well as the interaction between the formed Cu/Ni hybrid nanoparticles and the raw fruit extract respectively. These Cu/Ni BMNPs were evaluated for larvicidal potency against first, second and third instars of Culex quinquefasciatus. The larvicidal studies were carriedout at the concentration range of 5-50 mg/L (Cu/Ni BMNPs) and the %mortality increases with increase in concentration for all the instars. The result showed good activity where the lethal concentration values herein for the three instars were LC50=14.75, LC90=83.96; LC50=18.25, LC90=258.83; LC50=18.50, LC90=331.50 mg/L respectively. Therefore, Cu/Ni BMNPs could be a potential future nanolarvicide for Culex quinquefasciatus. Contribution/Originality:The study is one of a very few studies which have investigated fast green synthesis of Cu/Ni bimetallic nanoparticles and its larvicidal activity against larvae of Culex quinquefasciatus.

Plant mediated nanoparticles have been investigated to possess many applications in many fields such as pharmaceuticals, therapeutics and other commercial products. In this study, Copper/Cobalt bimetallic nanoparticles were synthesized by an eco-friendly and cost effective method using Palmyra palm fruit extract and characterized using various techniques such as UV-visible spectrophotometry and Fourier transform infrared spectrometry. Green synthesis method was used in obtaining the nanoparticles and the agar well diffusion method was used in evaluating the larvicidal activity. The resulting nanoparticles were evaluated to find possible application as nanolarvicide against first, second and third instar of Culex quinquefasciatus larvae in terms of percentage mortality. The lethal concentration values were LC50=12.036, LC90=143.316; LC50=14.774, LC90=263,456; LC50=16.076, LC90=296.758 ppm for the first, second, and third instars respectively implying moderate activity of this copper/cobalt nanoparticles. It could be concluded that copper-cobalt bimetallic nanoparticles synthesized using fruit extract of palmyra palm could be a potential nanolarvicide for mosquito larvae management. Contribution/Originality: This study contributes to the existing literature on Copper/Cobalt biological activity for control of mosquitoes in our environment.

Aims: Nanoparticles are gradually gaining wide scientific interest due to their various applications in catalysis, magnetism, medicine, optics, as antibacterial and nanolarvicidal agents. This research aimed at evaluating the larvicidal activity of green synthesized Ag/Ni BMNPs from the aqueous root extract of Borassus aethiopum as the stabilizing agent as well as their spectroscopic investigation using UV-Visible and FT-IR spectroscopy. Place and Duration of Study: The study was conducted in Gombe State University between August and December, 2019. Methodology: In this study, Ag/Ni hybrid bimetallic nanoparticles was synthesized using an eco-friendly method from the secondary metabolites of Borassus aethiopum acting as the reducing agent. Results: Optical measurements using UV-Vis showed the maximum absorption wavelength at 410nm while the FT-IR result for the root extract showed peaks at 3443.26cm-1, 2929.48 cm-1, 1651.28 cm-1, and 1080.12 cm-1 corresponding to OH stretch, sp3 C-H stretch, C=C stretch and C-O-C stretching respectively. These were replaced in the spectra of the BMNPs with the absence and appearance of some others indicating that they were involved in the capping process. The lethal concentration (LC50) was found to be 5.730, 13.585 and 15.735 mg/L for 1st, 2nd and 3rd/4th instars respectively. Also, the lethal concentration (LC90) was found to be 88.444, 195.689 and 236.889 mg/L for 1st, 2nd and 3rd/4th instars respectively. Conclusion: The larvicidal bioassay result showed a dose-dependent mortality rates against Culex quinquefasciatus larvae which suggest they can be developed to control the insect population.

One of the objectives of nanotechnology is to synthesize effective nanoinsecticides in a bid to reduce the prevalence of the numerous diseases caused by mosquitoes. This synthesis is even more vital in cases where phytochemicals from plants extracts are used as reducing agents. In this study, phytochemical screening of aqueous sprout extract of Palmyra palm (Borassus aethiopum) was performed, in accordance with some established methods and the results confirmed the presence of alkaloids, flavonoids, saponins, coumarins, glycosides, tannins, phenols as well as quinines, however, sterols, steroids and terpenoids were not detected. Subsequently, the sprout extract was used as a reducing agent in the synthesis of silver nanoparticles (AgNPs). Characterization with Fourier transform infrared and Ultraviolet-visible spectrometry was then carried out to confirm the synthesis. In addition, the AgNPs were further analyzed for larvicidal potency against 1st, 2nd 3rd and 4th instars Culex quinquefasciatus mosquito larvae, at interval concentrations of 5, 10, 20, 25 and 50 ppm. The LC50 and LC90 values discovered to be 9.103 ppm and 134.463 ppm with a correlation of 0.815, as well as 10.316 ppm and 118.810 ppm with a correlation of 0.801, for the 1st and 2nd instars, respectively. Meanwhile, the 3rd and 4th instars had LC50 and LC90 values of 17.585 ppm and 179.052 ppm, respectively, with a correlation of 0.807. This study provides a basis for extracting and analyzing the reduction potential of the phytochemicals present in the sprout extract, as well as the application of AgNPs, in controlling mosquito larvae population.