Prey species restrict limb regenerative growth in a ladybird beetle, Cheilomenes sexmaculata: allocation costs of regeneration?

Abstract

ABSTRACT In aphidophagous ladybird beetles, amputation of limbs in the larval stage leads to limb regeneration in adults. Regeneration is an energetically expensive phenomenon, and altering prey species may have profound consequences on this process. Therefore, we hypothesised that the quality of prey species will impact the ability to regenerate the lost limbs in Cheilomenes sexmaculata. For this experiment, we reared the larvae of C. sexmaculata on two aphid prey species: Aphis craccivora, which is the most preferred good-quality aphid, and A. nerii, which is the least preferred, poor-quality aphid. Although regeneration occurred in both dietary regimes, the extent of regeneration was higher in the beetles fed on A. craccivora. The length of the regenerated legs was shorter than the control/unamputated beetles, and it was further reduced when the prey species was of poor-quality indicating additional utilisation of resources for tissue repair and regeneration. Regeneration delayed pupal duration, post-amputation developmental duration and relative growth rate (RGR). Poor diet negatively affected developmental durations and RGR. Our results indicate prey dependency on regeneration and highlight energetic demands of regeneration and its associated developmental allocation costs.