Researchers worldwide have been looking forward to using novel ways to purify fresh water containing pollutants and disease vectors.

The spread of many infectious diseases by vectors is a globally severe issue. Climate change and the increase of vector resistance are the primary sources of rising mosquito populations. Therefore, advanced approaches are needed to prevent the dispersal of life-threatening diseases. Herein, Mn2O3 NPs and MnCoO nanocomposites were presented as mosquitocidal agents. The synthesized samples were prepared by a co-precipitation route and characterized using different techniques indicating the change of host Mn2O3 structure to 2D MnCoO nanoflakes with Co3+ integration. The thermal decomposition of the nanoparticles was examined by TGA analysis, showing high stability. The energy gap () of Mn2O3 was estimated within the visible spectrum of the value 2.95 eV, which reduced to 2.80 eV with doping support. The impact of Mn2O3 and MnCoO on immature stages was investigated by semithin photomicrographs exhibiting significant changes in the midgut, fat tissue and muscles of the third larval instar. Moreover, the external deformations in pupae were examined using scanning electron microscopy (SEM).

The present work aims to investigate the ultrastructural changes in the fat body of fifth instar nymphs Schistocerca gregaria (Orthoptera: Acrididae) treated with zinc chromium oxide (ZnCrO). The nanoparticles (NPs) were prepared by co-precipitation route and characterized using X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDX), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The ZnCrO NPs exhibited polycrystalline hexagonal structure, composed of spherical–hexagonal shapes with an average size ~ 25 nm. Besides, the UV–Vis spectrophotometer (Jasco-V-570) was utilized for optical measurements. The energy gap $$\left( {{\text{E}}_{{\text{g}}} } \right)$$ E g was estimated from the transmittance (T%) and reflectance (R%) spectra through the range of 3.307–3.840 eV. In biological sections, S. gregaria 5th instar nymphs, TEM images demonstrated that the fat body was strongly impacted with the concentration 2 mg NPs result in great agglomeration of chromatin in the nucleus as well as haemoglobin cells (HGCs) pierced with malformed trachea (Tr) at 5th and 7th days post treatment. The obtained results indicated a positive action of the prepared nanomaterial on Schistocerca gregaria fat body organelles. Graphical Abstract

Herein, we report the synthesis of spinel cobalt oxide nanorods (Co3O4 NRs) by a modified co-precipitation approach and examine their larvicidal activity against Culex pipiens. The structure and morphology of the as-prepared Co3O4 NRs were emphasized using X-ray diffraction (XRD), Raman spectroscopy, energy dispersive X-ray spectroscopy (EDAX), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). It was found that Co3O4 nanostructures have a face-centered spinel cubic crystal structure with a mean crystallite size of 38 nm. These nanostructures have a rod like shape with a mean diameter of 30 nm and an average length of 60 nm. The TGA measurements revealed the high stability of the formed spinel cubic structure at 400 °C. The optical behavior indicates the direct transition of electrons through an optical band gap in the range of 2.92 eV–3.08 eV. These unique chemical and physical properties of Co3O4 NRs enabled them to be employed as a strong agent for killing the C. pipiens. A comparison study was employed between the as-prepared Co3O4 and the entomopathogenic fungus Metarhizium brunneum as a control agent of C. pipiens larvae. The results revealed that the as-prepared nanorods have higher mortality against C. pipiens larvae compared with the well-known M. brunneum.

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The current work aims to improve the metal oxide characteristics for mosquito control. Un-doped and Y-doped CuO have been synthesized by simple chemical route. Structural, composition, and morphological properties were characterized by XRD, Raman spectra, EDX, SEM, and TEM techniques. The obtained results revealed that CuO was strongly affected by Y3+ support, in which the crystallite size decreased, and the surface area increased. Larvicidal performance was assessed against Culex pipiens suggesting that the nanocomposite CuO/Y of higher efficiency (LC50 = 7.67 mg /l, R2 = 0.977) compared with pure CuO. Light microscopy and SEM images exhibited larvae malformations owing to using the fabricated nanomaterials.

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Background The present work aims to investigate the ultrastructural changes in the fat body of fifth nymphal instars Schistocerca gregaria (Orthoptera: Acrididae) treated with zinc chromium oxide (ZnCrO). Methodology: The nanoparticles (NPs) were prepared by a coprecipitation approach. X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDX), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) were employed to investigate the structural, composition, and morphological properties. Results and discussion The ZnCrO NPs exhibited a hexagonal polycrystalline structure. SEM and TEM micrographs described the surface nature of the nanoparticles composed of spherical and hexagonal shapes with an average size of ~25 nm. The energy gap (Eg)of the Cr-doped ZnO thin film was estimated from the transmittance and reflectance spectra to be 3.307 and 3.840 eV. In biological sections, TEM images demonstrated that the fat body strongly impacted with the concentrations 2mg of the treated nanoparticles caused great agglomerated chromatin in the nucleus as well as haemoglobin cells (HGCs) pierced with malformed trachea. In addition, the same effect was observed at 1mg on the 7th day post treatment Conclusion The results indicate a positive impact of ZnCrO on Schistocerca gregaria leads to malformed of fat body organelles.