Anti-dengue potential and mosquitocidal effect of marine green algae-stabilized Mn-doped superparamagnetic iron oxide nanoparticles (Mn-SPIONs): an eco-friendly approach.

Vector-borne diseases pose a significant public health challenge in economically disadvantaged nations. Malaria, dengue fever, chikungunya, Zika, yellow fever, Japanese encephalitis, and lymphatic filariasis are spread by mosquitoes. Consequently, the most effective method of preventing these diseases is to eliminate the mosquito population. Historically, the majority of control programs have depended on chemical pesticides, including organochlorines, organophosphates, carbamates, and pyrethroids. Synthetic insecticides used to eradicate pests have the potential to contaminate groundwater, surface water, beneficial soil organisms, and non-target species. Nanotechnology is an innovative technology that has the potential to be used in insect control with great precision. The goal of this study was to test the in vitro anti-dengue potential and mosquitocidal activity of Chaetomorpha aerea and C. aerea-synthesized Mn-doped superparamagnetic iron oxide nanoparticles (CA-Mn-SPIONs). The synthesis of CA-Mn-SPIONs using C. aerea extract was verified by the observable alteration in the colour of the reaction mixture, transitioning from a pale green colour to a brown. The study of UV-Vis spectra revealed absorbance peaks at approximately 290 nm, which can be attributed to the surface Plasmon resonance of the CA-Mn-SPIONs. The SEM, TEM, EDX, FTIR, vibrating sample magnetometry, and XRD analyses provided evidence that confirmed the presence of CA-Mn-SPIONs. In the present study, results revealed that C. aerea aqueous extract LC50 values against Ae. aegypti ranged from 222.942 (first instar larvae) to 349.877 ppm in bioassays (pupae). CA-Mn-SPIONs had LC50 ranging from 20.199 (first instar larvae) to 26.918 ppm (pupae). After treatment with 40 ppm CA-Mn-SPIONs and 500 ppm C. aerea extract in ovicidal tests, egg hatchability was lowered by 100%. Oviposition deterrence experiments showed that in Ae. aegypti, oviposition rates were lowered by more than 66% by 100 ppm of green algal extract and by more than 71% by 10 ppm of CA-Mn-SPIONs (oviposition activity index values were 0.50 and 0.55, respectively). Moreover, in vitro anti-dengue activity of CA-Mn-SPIONs has good anti-viral property against dengue viral cell lines. In addition, GC-MS analysis showed that 21 intriguing chemicals were discovered. Two significant phytoconstituents in the methanol extract of C. aerea include butanoic acid and palmitic acid. These two substances were examined using an in silico methodology against the NS5 methyltransferase protein and demonstrated good glide scores and binding affinities. Finally, we looked into the morphological damage and fluorescent emission of third instar Ae. aegypti larvae treated with CA-Mn-SPIONs. Fluorescent emission is consistent with ROS formation of CA-Mn-SPIONs against Ae. aegypti larvae. The present study determines that the key variables for the successful development of new insecticidal agents are rooted in the eco-compatibility and the provision of alternative tool for the pesticide manufacturing sector.

Insecticide susceptibility in larval populations of the West Nile vector Culex pipiens L. (Diptera:Culicidae) in Saudi Arabia

Objective: To investigate the susceptibility to some conventional and non-conventional insecticides in laboratory and field larval populations of the West Nile vector Culex pipiens L. (Cx. pipiens), the dominant species in Jeddah Province, Saudi Arabia. Methods: The tested conventional insecticides were Actikil and Pesgard, while the non-conventional ones were Bacilod, Dudim and Baycidal. Probit analysis and photo-microscopical observations were carried out to shed light on acute toxicity in laboratory and field Cx. pipiens strains. Results: Cx. pipiens were more susceptible to Pesgard (LC50: 0.045 and 0.032 mg/L) than Actikil (0.052 and 0.038 mg/L) and Bacilod (0.129 and 0.104 mg/L), for the field and laboratory strains, respectively. Results showed that treatments with the chitin syn-thesis inhibitor Dudim and Baycidal evoked morphological effects similar to those induced by other insect growth regulators. According to IC50 values obtained (concen-tration which to inhibit the emergence of 50%of mosquito adults), the compound Dudim (0.000 3 and 0.000 1 mg/L) was more effective against Cx. pipiens L. mosquitoes than Baycidal (0.000 4 and 0.000 3 mg/L) for both the field and laboratory strains, respectively. Conclusions: Our results provide baseline data to enhance control programs and orient public health decisions on the selection of pesticides against mosquito vectors in Saudi Arabia.