Divergência genética entre cultivares comerciais de repolho quanto á prefer̂ncia do pulgão-da-couve

Abstract

The objective of this work was to evaluate the genetic divergence between cabbage cultivars, concerning the feeding preference of cabbage aphid (Brevicoryne brassicae). The experiment was carried out with 27 cultivars, in greenhouse, where the aphid preference was determined in assays with or without choice. A randomized block design was used with 27 treatments and five replicates. Mahalanobiś generalized distances were estimated and the cultivars were grouped by Tocheŕs method with seven groups formed. 'Chato de Quintal', 'Ryuho', and 'Taishita' were the less preferred cultivars by the aphid. The maximum distance was observed between the cultivars Das 4 Estações and Suki, the minimal distance occurred between 'Chato de Quintal' and 'Astrus Plus'. The number of nymphs is the variable that allows the highest differentiation between cultivars. There is variability between cabbage commercial cultivars as to aphid feeding preference.