Efecto de extractos acuosos procedentes de hojas de cuatro plantas sobre el ácaro rojo (Tetranychus urticae C.L.Koch) en laboratorio.

Abstract

The present investigation aims to evaluate the effect of aqueous extracts from leaves of four plants on the red mite (Tetranychus urticae C.L.Koch) in the laboratory. Samples of fresh leaves of Basil (Ocimum basilicum L), Lemon verbena (Cymbopogon citratus L), Rosemary (Rosmarinus officinalis L) and Alder (Alnus acuminata L) were collected in the main markets of the city of Riobamba, the aqueous extracts were obtained by steam distillation. This study was carried out using a completely randomized design with extracts of each species in 3 concentrations (25%, 50%, 75%), 6 treatments and three replicates were carried out in 25 ml tubs with 30 individuals per replicate, applying distilled water as a negative control and abamectin in strawberry leaves as a positive control. The percentage of mortality, repellency and residuality of extracts were evaluatedin this investigation, in which a greater number of dead mites was observed in treatmentT6 corresponding to Basil (Ocimum basilicum L) with a concentration of 75%, demonstrating the best acaricidal effect with an average of 27.33 individuals dead in 5 days. In terms of repellence, T2 corresponding to Alder (Alnus acuminata L) with a concentration of 50% showed a greater number of mites repelled with an average of 1.56individuals repelled, and in terms of residuality, chemical composition of the best extractwas carried out thin layer chromatography and the presence of the following compounds was determined: alkaloids, saponins, tannins, flavonoids and sterols. Aqueous basil oil with a concentration of 75% and Aqueous alder extract showed the best acaricidal effect.It is recommended to evaluate in mixtures with other oils extracted from other sources.