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

The objective of this study was to compare development of 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 larval period, pupal period, larval viability, and pupal viability of P. xylostella on kale and rocket leaves for 3 generations. We observed some significant differences in development among the generations and between the two crucifer varieties. The larval period differed significantly between the varieties only in the second and third generations, with means 10.3 and 11.3 days (2nd generation), and 7.6 and 6.8 days (3th generation) for kale and rocket, respectively. The larval viability differed significantly between the varieties only in the first generation, with means of 70.0 and 71.0% for kale and rocket, respectively. The pupal period was similar to the third generation. The pupal viability differed significantly between the varieties only in the first generation, with means of 80.0 and 59.0% for kale and rocket, respectively.  Generally, P. xylostella showed similar development of kale and rocket leaves to the third generation.