FREEZE TOLERANCE IN HERMIT FLOWER BEETLE (OSMODERMA-EREMICOLA) LARVAE

Larvae of Osmoderma eremicola (Knoch)(Coleoptera: Scarabaeidae) were f ound to be freeze tolerant. Early (1-2.5 cm) and late (3-5 cm) larval stages survived freezing to -8.3-degrees-C for 96 h with 64% of body w ater as ice. Glycogen phosphorylase activity in the fat body was incre ased 6-7-fold during freezing, and glycogen stores were depleted in fa t body (from 237 +/- 1 to 57 +/- 7 mumol/g fresh weight) and body wall (89 +/- 4 to 40 +/- 1 mumol/g fresh weight). However, no glycogen der ived cryoprotectants (glycerol, sorbitol, glucose, fructose) were foun d to accumulate in tissues or haemolymph during freezing or acclimatio n at 9, 0 and -5-degrees-C. Osmolality (approximately 450 mOsmol) of h aemolymph was constant during freezing and acclimation from 9 to -5-de grees-C, also suggesting the absence of low molecular weight cryoprote ctants. Haemolymph trehalose levels never rose above 2.7 mM as detecte d by NMR. Total protein levels in fat body and body wall remained unch anged during acclimation. HPLC analysis showed increases in amino acid levels by 10-15 mumol/g fresh weight in the body wall of both early a nd late instar larvae during freezing to -8.3-degrees-C for 96 h, with consistent increases in glycine (7.4-8.7 mumol/g fresh weight), alani ne (4.2-5.8 mumol/g fresh weight), glutamate (2.4 mumol/g fresh weight ), and valine (0.8-1.6 mumol/g fresh weight). Smaller increases in glu tamic acid (by 1 mumol/g fresh weight) and alanine (by 3.5 mumol/g fre sh weight) were also seen in late instar fat body, whereas glycine lev els remained unchanged and valine decreased slightly (by 1.4 mumol/g f resh weight) in this tissue. Proline levels, detected by NMR, ranged f rom 10 to 18 mumol/g fresh weight in fat body and 40-70 mumol/g fresh weight in haemolymph, making it the most abundant amino acid in fat bo dy.