Determinación de resistencia inducida en especies de zanahoria blanca (Arracacia xanthorrhiza BANCR) al ataque de Tetranychus urticae Koch (Acari: Tetranychidae)

Abstract

The two-spotted mite (Tetranychus urticae Koch) is an important pest in different crops, including the white carrot (Arracacia xanthorrhiza), however little is known about this plant-herbivore association. To determine the presence of possible mechanisms of resistance, the effect of feeding different densities of the mite (0, 2, 4, 6 and 8 mites / plant) on the activity of polyphenol oxidase (PO) and peroxidase (POX) was evaluated. ) at 24, 48 and 72 h after the infestation on white carrot plants of the five-month-old Quinchicoto and Baños cultivars, as well as the possible morphological barriers for feeding the mite. Additionally, the duration of the biological cycle of T. urticae in these materials was studied, using breeding units. No differences were observed in the different morpho-anatomical variables (cuticle-epidermis, parenchyma depth and trichome length) between the two evaluated materials. In relation to the biological cycle, the development time was significantly shorter in the cultivar Quinchicoto with respect to Baños and the control (strawberry leaves). The concentrations of oxidative enzymes produced by the plants of A. xanthorrhiza were also studied, where it was observed in general that the Quinchicoto cultivar showed the highest PPO values in comparison to the cultivated Baños (P <0.0082, F = 120, 47, gl = 1). Regarding the time after the infestation and density of the mite, the maximum expression values of the PPO were observed in plants infested with 6 and 8 mites / leaf at 48 and 72 hours, respectively in the cultivar Quinchicoto, while in the cultivate Baths, plants infested with 6 and 8 mites / plant showed the highest increases, although it was more evident with the density of 6 mites / plant (P <0.05, F = 66.289, gl = 9), while a behavior different was observed with peroxidase, since the highest values were observed in the cultivar Baños at 24 and 48 h after the infestation with 4 and 8 mites / plant, while the rest of the densities did not provoke a consistent response throughout the evaluation period. In plants of the Quinchicoto cultivar, the response did not show significant differences in the different times and densities evaluated.