Department of Biology
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Item Toxicity and perturbation of the metabolite contents by a chitin synthesis inhibitor in the mosquito larvae of Culiseta longiareolata(2011-01-01) Bouaziz, A; Boudjelida, H; Soltani, NNovaluron is an IGR of the benzoyl urea family, acting as a chitin synthesis inhibitor. The activity of a commercial formulation of Novaluron (10% EC) was tested, at different concentrations, ranging between 0.2 and 1.6 µg/l, against third and fourth-instar larvae of Culiseta longiareolata. (Diptera: Culicidae). The technical material showed a high level of activity with mortality recorded for both treated and following stages and happened after incomplete development. The LC50 values were 0.51 and 0.91 µg/l active ingredient for third and fourth instar larvae; and LC90 values were 2.32 and 4.30 µg/l respectively. In other experiments the compound was applied at LC50 and LC90 against the fourth instars larvae and its effects investigated on biochemical composition of larval body. Metabolite analyzes showed that novaluron affected significantly the amount of carbohydrates, lipids and proteins of fourth instars larvae starting from the day three following treatment. The carbohydrate and lipid amounts increased significantly whereas those of proteins decreased as compared with control series. For the same treated series a significant decrease was also recorded in the body weight with a decrease in development time. In the presence of chitin synthesis inhibitors, the last step of the chitin biosynthesis pathway is inhibited and the precursor is not converted in to chitin. It may either act on the hormonal level in the haemolymph to announce the synthesis, degradation or the inhibition of the metabolites. Than carbohydrates, lipids, proteins are under endocrine control and the exposure of the larvae to this xenobiotic product can modify the synthesis of these metabolites. The data obtained were discussed according to the mode of action of this insect growth regulator and the metabolism of lipids carbohydrates and proteins.Item Impact of an insect growth regulator on the development and the reproduction potency of mosquito(2017-04-18) Bouaziz, A; Khedidja, A; Djeghader, N.E; Aïssaoui, L; Boudjelida, H.Mosquitoes are medically and veterinary important vectors, responsible for the transmission of many human and animal diseases, such as malaria, yellow fever, dengue and West Nile Fever [1]. The management of disease vectors using conventional neurotoxic pesticides has failed because of the high reproductive ability, development of insecticide resistance of insect species and secondary effects on none target organisms and environment [2]. These reasons are leading the scientists to focus on the search of novel molecules without secondary effects. They proposed the insect growth regulators (I.G.Rs) as new pesticide alternative, that seem to be promising because of their specific mode of action on insects and their lower toxicity against non-target organisms; specially vertebrate, than conventional insecticides [3, 4, 5]. In the last decades, the I.G.Rs compounds have shown promising results in controlling insects of agricultural, medical and veterinary field [6, 7, 8]. Culex pipiens (Diptera, Culicidae) is the most widely distributed mosquito in the world and carries a number of diseases [9]. According to its large distribution, this represents the most interesting mosquito species in Algeria, particularly in urban areas and is generally controlled by conventional insecticides [10]. The disease spread depends directly on insect vector population and consequently, production of eggs by the insect could be a potential target for vector control. Therefore, the purpose of this study was to evaluate in laboratory, the effectiveness of an insect growth regulator, RH-0345, after treatment during the fourth instar larvae of the domestic mosquito Culex pipiens, and to provide better insights in the physiology of its mode of action.