ORIGINAL RESEARCH PAPER EFFICACY OF BIMETALLIC COPPER-ZINC NANOPARTICLES AGAINST LARVAE OF MICROFILARIAE VECTOR IN LABORATORY Savy P. Minal Environmental and Advanced Parasitology and Vector Control Biotechnology Laboratory, Department of Zoology, Faculty of Science, Dayalbagh Educational Institute, Dayalbagh, Agra, India Soam Prakash Environmental and Advanced Parasitology and Vector Control Biotechnology Laboratory, Department of Zoology, Faculty of Science, Dayalbagh Educational Institute, Dayalbagh, Agra, India*Corresponding Author INTRODUCTION Female mosquito Culex quinquefasciatus serves as the mechanical vector for many pathogenic agents responsible for disquieting diseases like Japanese encephalitis, Lymphatic filariasis, and West Nile fever [1]. Filariasis is one of the neglected tropical diseases (NTD), according to WHO over 1.23 billion people in 58 countries worldwide are threatened by the disease [2]. According to National Vector Borne Disease Control Programme (NVBDCP, India), Lymphatic filariasis is still a major public health problem in India after malaria and the indigenous cases have been reported from about 250 districts in 20 states/Union Territories. The two main parasites responsible for this disease in India are Wuchereria bancrofti and Brugia malayi [3]. Some of the basic strategies to control mosquito population employ primarily the use of synthetic chemical insecticides and secondary measures such as environmental management and biological control methods [4-6]. The use of synthetic chemical insecticides is potentially detrimental to public health and environment, as it affects non-target organisms which are responsible for biological control of mosquito resulting in the reappearance of insecticide-resistant vector population [7, 8]. Many insecticide resistant mosquito species were reported from 53 countries between the year 2010 and 2015, these mosquitoes were resistant to at least one class of synthetic chemical insecticide, therefore, threatening efficient vector control strategies through the chemical method and hampering the lowered mortality rate maintained by chemical control through the establishment of resistant species [9, 10]. New strategies to tackle the resurgence in vector-borne disease and thereby overall mortality rate in susceptible countries, led to an appeal for development of new tools to efficiently control vector population among these tools the use of nanoparticles is one [11-13]. Extensive research to check efficacies of different metal nanoparticles against insect vectors revealed the potency of nanoparticles in vector control. Several nanoparticles such as silver, gold, palladium, copper, zinc, silica and carbon nanoparticles, exemplified to be the best candidate for mosquito control [14-20]. Nanoparticles can be synthesized with the help of natural reducing and capping agents of biological nature, such as phytochemical extracts and other metabolites obtained from plants, fungi, algae, and microbes thus providing ecological soundness unlike synthetic chemicals [21-24]. New properties can also be studied with the induced changes in the geometry of nanoparticles with the help of LASER lights during synthesis [25]. Synthesis of a new class of material over the monometallic nanoparticles i.e. bimetallic nanoparticles may have unique catalytic properties over their monometallic forms [26-28]. The best combination of bimetallic nanoparticle formulation can effectively control mosquito vector population. In our study, we are reporting the efficacy of bimetallic copper-zinc nanoparticles against Culex quinquefasciatus mosquito larvae taking a step towards efficient vector control strategy for filariasis in tropical countries. MATERIAL AND METHODS Material Fresh leaves of Azardirachta indica (Neem) were collected from the botanical garden of Dayalbagh Educational Institute, Agra, India. Zinc Nitrate Hexahydrate Purified was purchased from LOBA chemie and Copper (II) sulphate pentahydrate Pure (cupric sulphate) was purchased from Merk. Larvae of Culex quinquefasciatus were collected from the local water body in Dayalbagh location, Agra, India, and identified by an insect taxonomist in the department of zoology, D.E.I., Agra. Triple deionized water was used in the preparation of nanoparticles. Preparation of Aqueous Extract Fresh leaves of Azardirachta indica, were washed and air dried. These leaves were then finely chopped and 15 g were transferred in 250-ml flask containing 100 ml of triple deionized water to make 15% solution. The preparation was heated on the hot plate at 70C for 1h, and the resulting crude leaf extract was filtered using whatman-1 filter paper and the final filtrate was then stored at 4C. Synthesis of Nanoparticles Bimetallic nanoparticle solution was synthesized by mixing Copper Sulphate (20 mM) and Zinc Nitrate (20 mM) in a 250-ml flask containing 90 ml of triple deionized water, to this molar solution 10 ml of prepared aqueous extract of Azardirachta indica was added, to make the volume up to 100 ml in 9:1 ratio. Monometallic nanoparticles were synthesized in a similar manner with Copper Sulphate (40 mM) and Zinc Nitrate (40 mM). After adding leaf extract these preparations were left at room temperature in dark for overnight. Characterization of Nanoparticles Absorption spectra were recorded using Microscan reader spectrophotometer model no. Microscan MS5608A. Plant extract, INTERNATIONAL JOURNAL OF SCIENTIFIC RESEARCH Zoology Volume-8 | Issue-2 | February-2019 | ISSN No 2277 - 8179 | IF : 4.758 | IC Value : 93.98 International Journal of Scientific Research 1 ABSTRACT The present study was conducted to test the larvicidal efficacy of Azardirachta indica (Neem) leaf extract mediated synthesis of bimetallic nanoparticles. It is to control the mosquito vector population. The quantity of both precursor agents to synthesize bimetallic nanoparticles was assigned half in amount as designated for the synthesis of each monometallic nanoparticles forms. Characterization was performed via Microscan spectrophotometer and photomicrographs were obtained through TEM. Efficacy was conducted on 3rd instar larvae of filariasis vector Culex quinquefasciatus (Say). Characterization results supported the formation of nanoparticles in the solution. Lethal concentration (LC50) was recorded and found effective against selected mosquito larvae. For copper nanoparticles the LC50 for 3rd instar larvae after 24h was recorded at 7% of the test concentration, after 48h it was at 3.5% and after 72h it was at 2%. However, the selected concentration of prepared zinc nanoparticles was not found effective against the selected larvae. For copper-zinc bimetallic nanoparticles the LC50 for 3rd instar larvae after 24h was recorded at 7%, after 48h it was at 5% and after 72h it was at 4%. Conclusively, the efficacy of bimetallic nanoparticles showed drastic improvement over monometallic forms, no potential larvicidal activity of zinc nanoparticle test concentrations was observed at selected concentration range, but in combination with copper nanoparticles in an equal proportion i.e. half of the monometallic forms, were found efficient in larvicidal activity when compared with the activity of copper nanoparticles. This could be a possible new strategy to control filariasis in tropical countries where filariasis is abundant. KEYWORDS Efficacy; Culex quinquefasciatus; Bimetallic nanoparticles; Vector control; Filariasis