Seasonal variations in antifreeze protein activity and haemolymph osmolality in larvae of the beetle Ragium mordax (Coleoptera: Cerambycidae).
Larvae of Rhagium mordax empty their guts in preparation for the winter, which alone may enable the larvae to supercool down to -20 degree C or below. This should be sufficient for the larvae to over winter in Denmark if they can prevent inoculation. Antifreeze proteins (AFP) prevent inoculation in adult Rhagium inquisitor and this is also likely in the larvae of R. mordax, as they are in contact with ice in their hibernacula during the winter. arvae of R. mordax probably produce AFPs in the early autumn, however, in some individuals thermal hysteresis (TH) as high as 5.01 degree C was observed in June. Whether or not these individuals have a constant level of TH in their haemolymph all year or if they produce further antifreeze proteins during the autumn is unknown. The lowest measured in January was 7.49 degree C (the highest during this month was 9.08 degree C) so it is likely that the individuals with the highest TH in June also produce AFPs. Haemolymph osmolality in R. mordax is relatively low compared to other freeze avoiding insects, samples taken in January peak at 741 mOsm (+/-127 mOsm). The results of this study are compared with similar data for the closely related R. inquisitor.
Wilkens
C
C
Department of Science, Systems and Models, Roskilde University, Denmark.
Ramløv
H
H
D000818:Animals; D021301:Antifreeze Proteins / Q000378:metabolism*; D001517:Coleoptera / Q000378:metabolism*; D003718:Denmark; D006458:Hemolymph / Q000378:metabolism*; D007814:Larva / Q000378:metabolism; D009994:Osmolar Concentration; D012621:Seasons; D013696:Temperature
D021301:Antifreeze Proteins