Changes in the concentrations of metabolites in haemolymph during and after diapause in female Colorado potato beetle, Leptinotarsa decemlineata

Abstract

Haemolymph concentrations of proline and other free amino acids, glucose, total lipids and total proteins, including the typical diapause proteins and vitellogenins, were measured at various stages in the diapause of adult Colorado potato beetles. The concentration of the various metabolites is much higher in the haemolymph of diapausing females than in that of non-diapause females. The specific haemolymph composition of diapausing Leptinotarsa decemlineata (Say) displays similarities with that of other insect species diapausing as larvae or pupae. The change from diapause development (3 months) to post-diapause quiescence is reflected in alterations in the levels of total haemolymph proteins. Results show that most of the reserves accumulated during the pre-diapause period are used for resumption of activity and start of reproduction. Thus the ‘diapause proteins’ seem to have no diapause-specific function but may have a role in post-diapause development. Comparison with results obtained from females diapausing at a higher temperature indicates that specific metabolic changes arise in response to cold in diapausing beetles. Diapausing beetles are better able to resist sub-zero temperatures than non-diapause active adults. Haemolymph may play a role in enhanced cold tolerance as reflected by its higher osmolarity during diapause at low temperature. Finally, proline appears to have a cryoprotective function, rather than an energetic one, during diapause.