Variación intraespecífica de Tetranychus urticae Koch (Acari: Tetranychidae) en fresa (Fragaria sp.)

Abstract

Tetranychus urticae is an important phytophagous mite in agriculture due to its economic impact on different crops, including strawberries. This species, like several species of Tetranychidae, shows a wide phenotypic variability that makes their correct identification difficult. Thus, in this study the intraspecific variability of Tetranychus urticae Koch in strawberry (Fragaria sp.) was studied. Mites were collected from strawberry leaves showing characteristic symptoms of tetranychid feeding in municipalities of Ambato, Tisaleo, and Pelileo in the province of Tungurahua. In each female specimen, the lengths of the idiosomal dorsal setae (ve, sci, sce, c1, c2, d1, d2, e1, e2, f1, f2, h1, IC1, c3, c4) and ventral (h2, h3) and the distance between them and subjected to Principal Component Analysis (PCA). According to the results, the PCA of the lengthof the idiosomal setae showed that 93.14% of the morphometric variation of T. urticae was explained in 10 components. The morphometric variables that showed the greatest weight in component 1 were the length of the setae c1, c2, c3, d2, e2, f2 and h3, while incomponent 2, the variables with the greatest weight were the length of the seta Sc1, d1, e1, f1 and f2. Regarding the distance between setae, it was also found that the first 10 components explained 94.67% of the variability, of which in the first component most ofthe variables (v2-v2, sc1-sc1, c3-c3 , d1-d1, d2-d2, ee2-e2, f1-f1, h2-h2 and h3-h3) showed the highest specific weights to explain the variation of the populations, while in the second quadrant the distances sc2-sc2 , c1-c1, c2-c2 reached the highest values and finally in the third component only the distance sc2-sc2 was relevant. With these results, the importance of these morphometric variables for the characterization of the species was evidenced and allowed to separate the population of T. urticae from Pelileo, while the populations of Ambato and Tisaleo were not clearly separated.