Limb regeneration is blastema dependent in a ladybird beetle, Cheilomenes sexmaculata (Fabricius)

Abstract

Holometabolous insects undergoes metamorphosis which involves an intercalated pupal stage between larva and adult. The body plan of the adult is established during pupal stage and larval systems are de-differentiated and reorganized in insects undergoing complete metamorphosis. In ladybird beetles, limbs amputated in larval stages are regenerated in adults. This occurs during pupation. Given that changes in pupa are akin to embryogenesis, does the lost limbs are redeveloped as a part of metamorphosis or has some pre-patterning initiated prior pupation? To study this we hypothesised that limb regeneration in a holometabolous ladybird beetles, Cheilomenes sexmaculata is the result of the recapitulation of the embryonic gene programs in the pupa. To test this, we exposed third larval stages of C. sexmaculata to amputation and prior to amputation the tissues on the amputated site was scraped off every 24hrs. It was found that limb regeneration does not occur in the treatment where scrapping was done. Assuming that these epidermal cells correspond to blastema, for limb regeneration in ladybird beetles blastema is essential and does not occur in its absence.