Abstract

The acaricidal potential of Melia azedarach, Peganum harmala, Nigella sativa and Trigonella foenum-graecumseeds was investigated on adult Tetranychus urticae under laboratory conditions. After the treatment of foliar discs using dichloromethane and ethanol extracts of these seeds, the statistical analysis of the mortality percentage revealed that N. sativa was the most potent one. In fact, using the dichloromethane extracts, the LC₅₀s were 398.64, 410.48, 73.95 and 520.74 ppm for the four species respectively. Whereas, for ethanol extracts, the LC₅₀s were 994.93, 617.26, 92.96 and 1074.81 ppm respectively. n-Hexane, trichloromethane and ethyl acetate fractions of N. sativa dichloromethane extract used in the same manner showed that n-Hexane fraction was the most toxic with LC₅₀=74.34 ppm followed by trichloromethane fraction with 96.74 ppm then ethyl acetate with 104.27 ppm. The phytochemical analysis of these fractions revealed the presence of some metabolites which could explain their toxicity.

Key words: Acaricidal potentials, extract, fractions, ethanol, dichloromethane, Tetranychus urticae, phytochemical analysis