ABSTRACT
Tetranychus urticae is considered one of the most important mite species, attacking several agricultural crops. The aim of this work was to verify, in the greenhouse, the acaricide activity of some plant extracts on a population of T. urticae, infesting bean plants. Each plot consisted of 5 bean plants with 7 to 10 leaves previously infested with 5 T. urticae females each. The plant species used were Allamanda cathartica, Dieffenbachia brasiliensis, Pennisetum purpureum, Annona squamosa, Ruta graveolens, Sonchus oleraceus, Spondias purpurea, Codiaeum variegatum, Impatiens walleriana, Stryphnodendron barbatiman, Solanum melongena, Agave angustifolia and Allium cepa. The vegetable material collected was dried in an oven at 40º C and after that triturated, and the resulting dust was submitted to extraction with distilled water for 14 hours and then filtered. The filtered residues were utilized for tests after a period of 30 to 45 days of infestation, when they were applied on infested plants in doses of 100 mL of extract/L of water utilizing a knapsack sprayer of 5 L. Previously and 7 days after treatment an evaluation was made of the number of live mites (active stages) on 1cm2 of 10 leaves in each plot. The aqueous extracts of D. brasiliensis, R. graveolens, A. cepa, A. angustifolia and A. squamosa promoted a significant reduction of the T. urticae population, showing 86.87%, 83.95%, 80.97%, 76.30 and 75.40% efficiency, respectively.
KEY WORDS
Tetranychus urticae
; natural products; acaricide; control