TOXICITE COMPAREE DES HUILES ESSENTIELLES BRUTES FOLIAIRES DE TROIS PLANTES SPONTANEES RECOLTEES AU SAHARA ALGERIEN SUR LES LARVES ET LES IMAGOS DE Schistocerca gregaria (FORSKÅL, 1775) (ORTHOPTERA-CYRTACANTHACRIDINAE)

Abstract

The study of the directly contact toxicity of crude leaf essential oils of Peganum harmala L. (Zygophyllaceae), Cleome arabica L. (Capparidaceae) and Cymbopogon schoenanthus L. (Poaceae) collected in the Algerian Sahara, on the fifth stage larvae (L5) and adults of desert locusts, reveals their toxicity in this locust. For crude essential oils of P. harmala, a mortality rate of 100% is reached after 8 mn 30', in L5 larvae treated. It is 12 mn 10' for C. Arabica and 35 mn 11' for C. schoenanthus. A 100% mortality is reached in imago treated after 30 mn 18', 128 mn 40', 63 mn 19 et for P. harmala, C. arabica and C. schoenanthus respectively. No deaths recorded at the level of L5 larvae and adult forms of the control groups. L5 larvae appear to be more sensitive to the raw leaf essential oils of these plants acridifuges tested compared to adult individuals. Examination of the lethal time 50 (LT50) for L5 larvae shows that the shortest time is obtained with the raw leaf essential oils of P. harmala (6 mn 12') and C. arabica (9 mn 17') and