LABORATORY ADAPTATION AND INBREEDING IN HELICOVERPA-PUNCTIGERA (LEPIDOPTERA, NOCTUIDAE)

Inbreeding in the noctuid moth Helicoverpa punctigera was examined by crossing moths within and between families set up from field-collected females. There were large inbreeding effects for larval viability, and smaller effects for adult size and larval/pupal developmental time. Size and developmental time were compared in two recently collected strains from Western Australia and Victoria, and in two strains from these locations held in the laboratory for eight or 12 generations. In both laboratory-adapted strains, the length of a hindwing vein was reduced and the time spent at the pupal stage was extended. There were also changes in pupal weight but these were inconsistent. Means of F1s from crosses between the strains were intermediate for hindwing length and pupal weight, while F1 means for pupal developmental time were similar to those of recently collected strains. This suggests that some changes in established stocks were due to laboratory adaptation rather than inbreeding. A comparison of lines held for one or four generations in the laboratory indicated changes in hindwing length and pupal developmental time in the same direction as those observed in crosses between established and new laboratory stocks.