Efficacy of some insecticides on field populations of Culex pipiens (Linnaeus) from Egypt

The efficacy of the most used insecticides belonging to different groups (organophosphate, carbamate, synthetic pyrethroid and insect growth regulator) was tested against four different field populations of Culex pipiens. Results obtained showed that the laboratory colony showed higher susceptibility to the tested insecticides than the mosquito populations collected from Sharkia and Assiut Governorates. Field populations of Cx. pipiens from Sharkia were chosen to study the development of resistance (resistant strain) in Cx. pipiens to chlorpyrifos toxicity. After 15 generations of selection pressure using chlorpyrifos against the 3rd instar larvae of Cx. pipiens, resistance increased by 24.56-fold in the resistant strain as compared with the control. Fractionation of total soluble proteins using SDS–PAGE revealed some differences in the laboratory colony, field populations and resistant strain. Results may indicate that alkaline phosphatase and non-specific esterases were probably responsible for the detoxification of chlorpyrifos in field populations

Variations in heavy metal concentrations among trophic levels of the food webs in two agroecosystems

Excessive accumulation of trace metal in soil represents a growing environmental problem posing severe risks to biota, humans and ecosystems. concentrations of cd, Pb, cu and Zn were determined in soil, as well as in representatives of some trophic levels in the terrestrial food webs in two Egyptian agroecosystems; El-Manzala (a rural area located in the northeast of the River Nile delta) and El-tebbin (an industrial area located in South cairo). Representatives of trophic levels included arthropods, amphibians, reptiles, birds and small mammals. Metal concentrations were determined in the leaves of wild plants, bodies of arthropods and livers of vertebrates. Levels of metals in the soil, plants and most animal species were higher in El-tebbin than El-Manzala. Minimal concentrations of metals were detected more often in plants and in the cattle egret, whereas maximum values were common in the soil, amphibians and a mantid. Accumulation of metals was more frequent in arthropods and other taxa at lower trophic levels of food webs, suggesting that the transfer of metals along the vertebrate food web may be of relatively minor importance. However, of all the metals examined, only Pb was bioaccumulated to any appreciable extent in some of the higher trophic levels. A significant increase in liver mass and relative liver mass of the Norway rat from the polluted site was observed.keywords: environmental problems, liver, plant, soil, trace elements, wild animal

Molecular phylogeny and identification of the Egyptian wasps (Hymenoptera: Vespidae) based on COI mitochondrial gene sequences

Abstract The Hymenoptera is one of the vital and biggest insect orders comprising the bees, wasps, sawflies, and ants. Wasps are important to natural and biological pest control because they are predators or parasitoids of pest arthropods. This study investigated the genetic diversity among the three wasps, Vespa orientalis Linnaeus, Polistes bucharensis Erichson, and Polistes mongolicus du Buysson, collected from three different governorates in Egypt, using cytochrome oxidase subunit I (COI) DNA barcoding. PCR was performed to amplify COI fragment. The amplified COI regions (710 bp) were sequenced and analyzed. All novel nucleotide sequences of COI gene were deposited into the GenBank database. The genetic distances were estimated using Kimura two-parameter model. In spite of the wide geographical range, minor genetic diversity was observed between some populations of the three wasp species, revealing unrestricted gene flow between them. Phylogenetic relationship analysis was performed, using maximum likelihood (ML) method. The results of the phylogenetic analyses recovered P. bucharensis more closely related to P. dominula and P. gallicus. P. mongolicus collected from Menofia Governorate formed a distinct branch with 99% support. V. orientalis was sister to the yellowjacket Dolichovespula adulterine, with 84% support. It can be concluded that DNA barcode is a powerful tool for rapid and accurate identification of Egyptian wasp species

The antiviral activities of Egyptian ethanolic propolis extract and honey bee venom against honey bees infected with multiple viruses in vitro

The demand for using natural compounds as control methods for honey bee viruses have increased in recent decades. In this study, a chemical profile of honey bee venom (HBV) has been determined by FTIR spectroscopy and Egyptian ethanolic propolis (EP) extract by GC-MS and HPLC. Also, the enzymatic activities of HBV were determined. HBV and EP were tested for antiviral activity. The cytotoxicity and cell viability were evaluated using the MTT assay. The results revealed the first identification of methyl gallate and phthalic acid using GC-MS and HPLC. HBV and EP showed antiviral activity against honey bee cell lines infected with deformed wing virus, black queen cell virus, Varroa destructor virus-1 and Kakugo virus. Also, cell proliferation was determined after incubating with HBV and EP, cells were produced with no evidence of cell death up to 1 g/L for HBV and 5 g/L for EP, despite cytotoxicity that was determined at higher doses of both treatments. The data demonstrated that EP and HBV exhibited a significant reduction of all identified viruses in the cultured cell. These findings suggest that HBV and EP in low concentrations could be used as potential supplements and antiviral drugs in honey bee apiaries.</p