Feeding preference of Plutella xylostella (L.) (Lepidoptera: Plutellidae) on kale and rocket

The objective of this study was to compare the feeding preference of Plutella xylostella on varieties of crucifers. We used 2 varieties of crucifers, kale ‘HS20’ (Brassica oleracea var. acephala) and rocket ‘folha larga’ (Eruca sativa). We performed 5 replicates; each replicate was 1 acrylic cage (12 cm diameter) containing four 2-cm-diameter leaf discs for larval feeding. In each cage, we placed 10 P. xylostella larvae. In order to evaluate feeding preferences, in each acrylic cage, we performed a dual-choice test, using 2 foliar discs of both kale and rocket positioned equidistant from each other. For the feeding preference evaluations, we reared P. xylostella larvae on the leaves of kale or rocket for 4 generations. In the second generation, the larvae reared on kale (51.0% of larvae on kale and 49.0% on rocket) and rocket (41.2% of larvae on kale and 58.8% on rocket) showed no significant feeding preference. In the third generation, the larvae reared on kale (33.3% of larvae on kale and 66.7% on rocket) and rocket (45% of larvae on kale and 55% on rocket) again showed no significant feeding preference. In the fourth generation, the larvae reared on kale (56.5% of larvae on kale and 43.5% on rocket) and rocket (43.8% of larvae on kale and 56.2% on rocket) once again showed no significant feeding preference. Therefore, in the laboratory, larvae of P. xylostella reared on kale and rocket leaves showed no significant preference for either of these 2 crucifers up to the fourth generation.