Fluctuaciones poblacionales de araña roja (Tetranychus urticae) en diferentes cultivares de fresa (Fragaria) en el cantón Cevallos, provincia de Tungurahua

Abstract

Strawberry (Fragaria x ananassa is cultivated worldwide, and, like other crops, yield can be affected by different species of phytopathogens, insects and phytophagous mites, including the two-spotted mite, Tetranychus urticae. In view of the importance of this mite species, the present study evaluated the population fluctuation of T. urticae in strawberry cultivars in Cevallos, province of Tungurahua. Every 15 days strawberry leaves from cultivars Albión and Monterrey showing feeding symptoms caused by tetranychids were collected. Samples were taken to the laboratory and examined under magnification of the stereoscope microscope to count the number of mites and thus estimate the population variation in relation to the intra-plant and temporal distribution of the pest in this crop. An effect of the cultivar on the number of mites was demonstrated with the highest population level on plants of the cultivar Albion. Regarding the intraplant distribution, no differences were observed in the different plant strata in the cultivar Albión, while in Monterrey the highest density of mites was observed in the middle stratum. Finally, the population variations as a function of the sampling time showed wide variations of T. urticae on cultivar Albión, while conversely no significant differences were detected between the sampling dates in the cultivar Monterrey. Differences in mite density, intra-plant distribution and temporal variations in strawberry cultivars could be related to the host plant resistance mechanisms, however, this should be studied, mainly related to the density of leaf glandular trichomes