Effet insecticide du Melia azedarach sur Thaumetopoea bonjeani Powell du cèdre de l’Atlas cas d’Ouled Yaagoub

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Université Abbes Laghrour -Khenchela-
ABSTRACT The evaluation of the insecticidal potentialities and the larvicidal activity of the aqueous and ethanolic extracts of Melia azedarach regarding the processionary caterpillar of cedar "Thaumetopoea Bonjeani" in stage L4, was carried out by testing 3 doses: 100, 500 and 1000 ppm of each extract under laboratory conditions. The results showed a lethal larvicidal effect of both extracts compared to the results recorded in the controls. On the other hand, the aqueous extract of the leaves seems harmless at low doses on the larvae on L4 stage. Regarding the transformation of larvae into chrysalis, our results have shown that fruit extracts strongly stimulate this transformation. Conversely, what has been observed for the aqueous extract where the results are nil for almost all concentrations and regardless of the treatment time. These results are similar to those of the anti-appetizing activity where the effect is more pronounced for fruit extracts than leaves. The test on the black Ant Formica glacialis showed that ants are sensitive to different extracts and doses of Melia azedarach. The difference in yield of our extracts is probably due to the extraction techniques used, which are totally different and to the chemical composition which differs from one extract to another and also to the duration of the treatment which increases the mortality in the larvae.