Leaf consumption by Plutella xylostella (L.) (Lepidoptera: Plutellidae) on kale and rocket

The objective of this study was to compare leaf consumption by Plutella xylostella feeding on 2 varieties of crucifers, kale ‘HS20’ (Brassica oleracea var. acephala) and rocket ‘folha larga’ (Eruca sativa) for 3 generations in the laboratory. The insects used in this study were obtained from P. xylostella reared on kale leaves. We performed 10 replicates for each variety; each replicate was an 8-cm-diameter leaf disc placed in a Petri dish containing 10 newly hatched larvae. Subsequently, the dishes were sealed with plastic film to prevent the insects escaping. Larvae were maintained in dishes with leaves until the pupal stage. We evaluated the consumption of P. xylostella larvae on kale and rocket leaves until the pupal stage for 3 generations. We observed some significant differences in leaf consumption among the generations and between the two crucifer varieties. In the first generation, leaf consumption did not differ significantly between the varieties, with means of 37.1 and 45.9 cm² for kale and rocket, respectively. In the second generation, the leaf consumption was higher on the leaves of rocket (27.9 cm²) than on kale (17.2 cm²). In the third generation, the leaf consumption of larvae was again similar between the varieties, with means of 31.5 and 33.7 cm² for kale and rocket, respectively. Generally, P. xylostella consumed similar amounts of kale and rocket leaves. Therefore, care is needed when planting these 2 varieties in neighboring areas, since this will hinder the control of this pest, which can migrate from one area to another.