Biological efficiency of Ocimum basilicum L. hydroalcoholic formulations against whitefly, Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae) on tomatoes and their effects on a ferruginous soil microorganisms, in Burkina Faso

Résumé

AbstractA biological efficiency study of different doses of Ocimum basilicum L. hydroalcoholic formulations against whitefly, Bemisia tabaci which causes big damage to tomato has been done at the Kou Valley, in Burkina Faso. The experimentation was a randomized block design of five treatments: untreated control, K-optimal (Lambda-cyhalothrin (15 g/L) + Acetamiprid (20 g/L)) at 1 L/ha; O. basilicum at 78.12 L/ha; O. basilicum at 156.25 L/ha and O. basilicum at 260, 42 L/ha in four replications. The biological efficiency coefficients of the hydro-alcoholic formulations were determined by Afanaseva and al. (1983) formula. The soil microorganism’s number was evaluated on agar media culture (Tepper and al., 1987). Between the different rates of O. basilicum formulations, the rate of 260.42 L/ha resulted in a similar mortality to K-optimal at 1 L/ha. Its efficiency coefficients varied from 3.25 to 75.70 in comparison with the untreated control. The efficiency coefficients of 156.25 L/ha varied from 2. 36 to 69.76 and those of the 78.12 L/ha varied from 1.46 to 64.76. However, if the O. basilicum formulation at 260.42 L/ha inhibited the number of ammonifying bacteria by 78.80%, on the other hand it stimulated the nitrifying bacteria by 234.41% in comparison with the untreated control at this stage. All of these factors allowed to obtain for O. basilicum at 260.42 L/ha formulation a yield increase of 17.53% in comparison with the untreated controlKeywords: Ocimum basilicum, Bemisia tabaci, tomato, soil microorganisms, Burkina Faso.