Comparative evaluation of the toxicity of lambda cyhalothrin and spinosad on the insect pests and auxiliary fauna in an orange orchard of the central Mitidja (Blidean Atlas, Algeria)
Authors: 1Allal-Benfekih L., 1Aoudia B., 1Mostefaoui H. & 2Belguendouz R
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Impact of phytosanitary treatments on time variation in the abundance and diversity of the insect fauna was evaluated on an orange orchard in Central Mitidja. The ecotoxicity of Lambda-cyhalothrin and spinosad applied to the approved dose and half-dose were evaluated through the abundance and availability of pest populations and associated auxiliary procession after a period of 16 days exposure. Our results showed that Lambda-cyhalothrin has a toxic effect on the aphid residual population during 12 days after treatment, which is moderately toxic from the 13th to the 16th day, while spinosad has a neutral effect during the hole exposure period. Community of the insect fauna harvested during the 16 days of observation after treatment consists of 12 species of phytophagous, 11 parasits and 13 predators. Under the effect of the approved dose of Lambda-cyhalothrin, temporal fluctuation pest shows a slight increase in the first 12 days with a significant difference compared to control (23.30% in 12 days). The Aphididae, Phyllocnistis citrella and Ceratitis capitata are the most influenced unlike Coccidae, Aleurodidae and Tetranychus sp. The similarity analysis to one factor shows very highly significant differences between two types of treatments and between each treatment group and the controls. These differences may be due to variations in the relative abundance of different taxa or species composition of communities. Lowest contribution differences are recorded in parasitoïds and Chrysopidae. Key words: pesticides, ecotoxicology, beneficial ennemis, pests, crops, auxiliary fauna assemblages.