Fahad Kaoutar, Brhadda Najiba, Ziri Rabea, Benssallem El Hassan, Gmira Najib
Abstract: In an attempt to elaborate a strategy of integrated pest management on citrus fruits in Morocco, the biocide activities of two essential oils on citrus black aphid Toxoptera aurantii infesting citrus and a potential vector of closterovirus, was studied in the laboratory. Both essential oils emulsified in 2 % carboxymethylcellulose sodium water and 12.5 % of saccharose were applied to 10; 5 and 2.5 ml.l-1. With regard to checks, both essential oils significantly affected the survival of the pest, during all the period of the treatment. As to the cedars oil Cedrus atlantica, three concentrations were significantly different from the check. The concentration 10 ml.l-1 caused the mortality of nearly all individuals treated, after one day of exhibition. In the term of the experiment, the concentration 5 ml.l-1, caused mortality estimated in: 50.25; 51; 52; 54.88 and 56.75 %, respectively, for the first, second, third, fourth stage larva and the adult stage; after the same duration, the concentration 2.5 ml.l-1 engendered a low mortality, but significantly different from the check. The values of the CL50 were comparable between the four larval stages. They were estimated at 6.14; 6.13; 6.05 and 6.00 ml.l-1, for the first, second, third and fourth stage larvae. The TL50 of the concentration 5 ml.l-1, was estimated at: 86; 82; 57; 56 and 23 hours, respectively, for the first, second, third, fourth larval stage and the adult. Concerning the efficiency of the Eucalyptuss oil on T. aurantii, it engendered a global average mortality of about 43 + 0.37 %. As to the C. atlanticas oil, the concentration 10ml.l-1 provoked the mortality of most of the adults treated, which were comparable between five target stages. It bordered 93.63 %. The CL50 was estimated at 6.80; 6.62; 5.98; 5.93 and 4.92ml.l-1, successively for the first, second, third, fourth larva stage and the adult. The values of Henrys rights and the CL90, confirm the strong toxicity of Eucalyptuss oil on T. aurantii. The TL50 provoked by 5ml.l-1 concentration was estimated at 72; 69.14; 31.14; 30.20 and 19 hours, for the first, second, third, fourth larval stage and the imago. In spite of the efficiency of this bio-insecticide, all the concentrations applied, provoked the appearance of the reactions of phytotoxicity on the treated leaves.
Keywords: biocide, Toxoptera aurantii, essential oils, Cedrus atlantica, Eucalyptus grandis, management, citrus, Morocco