Preference of Plutella xylostella to different cruciferous vegetables across 18 generations

Host location has been extensively studied in both imaginal and pre-imaginal diamondback moth (DBM) Plutella xylostella (L.) (Lepidoptera: Plutellidae) by using oviposition preference in immature and adult females exposed to various types of learning experiences. However, no evidence of pre-imaginal conditioning that influenced the behavior of the imago was observed. The aim of the present study was to evaluate the preference of 18 generations of DBMs to different cruciferous vegetables, namely, Brassica oleracea var. acephala (HS-20 kale), B. oleracea var. italica (Piracicaba broccoli), and B. oleracea var. capitata (Bobcat cabbage). Three populations of DBMs were examined using the variables feeding and oviposition substrate during rearing on kale, broccoli, and cabbage. The DBMs derived from each rearing substrate were separated every three generations and subjected to multiple-choice tests (i.e., preference for feeding and oviposition). In generation F18, insects that emerged from larvae reared on broccoli showed oviposition preference on broccoli sprouts (43.1%). Insects that emerged from kale-reared larvae preferred to lay their eggs on broccoli (41.7%) and cabbage (34.9%), whereas insects that emerged from larvae reared on cabbage showed oviposition preference on cabbage (43.2%). In this generation, the DBMs showed no feeding preference using the three cruciferous vegetables. Until the 18^th generation, the DBMs were influenced by nutritional factors related to the host’s choices of substrate to feeding on, which did not influence oviposition behavior. DBMs conditioned to feed and lay eggs on different substrates for generations did not affect the pre-imaginal or imaginal preference of the insects.