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

Margosa oil (Azadirachta indica) extract as biopesticides were examined against Culex pipiens mosquito larvae under laboratory conditions to detect the toxicity of margosa oil extract and study the histopathological alterations in the midgut of treated larvae. The inhibition influence of plant extract was assessed by determining the mortality of larvae post-treatment with LC50 value11.59 ppm. The crude extract of margosa oil recorded 90% mortality for Cx. pipiens at 80 ppm. In contrast, the lowest concentration of extract recorded 30% mortality. Histological analyses showed that treated larvae had cytopathological alterations of the midgut epithelium. The treatment at high concentrations of margosa extract showed more damage in the gizzard and midgut region, leading to death. On the other hand, the treated larvae with low concentration exhibited little changes in the gizzard dendrites. The study provided that margosa oil is promising as a larvicidal agent against Cx. pipiens, naturally revolved biopesticides would be an alternative to chemical insecticides.

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.