The journal of Toxicology and pest control is one of the series issued twice by the Egyptian Academic Journal of Biological Sciences, and is devoted to publication of original papers related to the interaction between insects and their environment. The goal of the journal is to advance the scientific understanding of mechanisms of toxicity. Emphasis will be placed on toxic effects observed at relevant exposures, which have direct impact on safety evaluation and risk assessment. The journal therefore welcomes papers on biology ranging from molecular and cell biology, biochemistry and physiology to ecology and environment, also systematics, microbiology, toxicology, hydrobiology, radiobiology and biotechnology. www.eajbs.eg.net

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Background: Waste product compound of rice bran and lufenuron are considered safe compounds to the human and to the environment. They can be used to control Schistocerca gregaria. Objective: The aim of the present study is to examine the ultrastructural changes and histopathological alteration in the Schistocerca gregaria embryogenesis induced by selected waste product compound of rice bran (Oryza sativa) and a chitin synthesis inhibitor (lufenuron). Materials and Methods: Histological and ultrastructure study of normal and affected eggs of Schistocerca gregaria were conducted to demonstrate the effects of lufenuron and rice bran extract on the embryogenesis. Cleavages started about 5 hrs post oviposition (pop) and continue to divide until formation of cellular blastodrem by 1 day pop. By 2 days pop germ band is formed, differentiated into ectoderm and mesoderm. At 3 days pop segmentation of germ band into mouthpart and three thoracic segments occur. Antenna was observed at 3 days pop. Fore and midgut were detected by 5 days pop. Hindgut was also observed by 5 days pop. By 4 days pop, eyes and brain appeared. Brain appeared as two ganglionic masses separated by oesophagus, which by 5 days pop appears as 2 large interconnect cerebral lobes enwrapped by neurilemma. Histological section of affected eggs showed great effects on brain, alimentary canals and compound eyes. Results: Ultrastructure study of newly deposited eggs showed that, the chorion consists of several easily distinguishable layers and in 30-hour-old eggs, cleavage nuclei of different shapes could be observed. The nuclei of the blastoderm cell have spindle shape and have condensed chromatin, which attaches to nuclear membrane. Electron micrograph of lufenuron-affected eggs revealed abnormal chorion and cleavage nuclei. In rice bran affected eggs, disintegrated blastoderm that failed to arranged and sever malformed nuclei were seen. Vaculation and lysis of cell components leaving cavities within the ooplasm were detected in both treatments. Conclusion: The tested compounds induced serious changes to the embryos of Schistocerca gregaria as revealed by the histological and ultrastructure studies.

Laboratory experiments evaluated the latent effects of lufenuron and rice bran extract on the newly hatched nymphs of Schistocerca gregaria produced from females who were treated as fifth nymphal instar with LC50 of each lufenuron and rice bran extract. Semithin sections of the newly hatchling showed great histological malformations in the structure of the brain, compound eyes, midgut, and hind leg muscles compared with control, these organs lost their normal structures, shapes, and functions. The tested compounds had serious extended histopathological effects, so they can be used to control S. gregaria as safe alternative agents to toxic synthetic pesticides.