Feeding impairs chill coma recovery in the migratory locust (Locusta migratoria).
Low temperature causes loss of neuromuscular function in a wide range of insects, such that the animals enter a state known as chill coma. The ability to recover from chill coma (chill coma recovery time) is often a popular phenotype to characterise chill tolerance in insects. Chill coma in insects has been shown to be associated with a decrease in haemolymph volume and a marked increase in [K(+)], causing dissipation of K(+) equilibrium potential and resting membrane potential. High potassium diet (wheat) has also previously been shown to increase haemolymph [K(+)] in Locusta migratoria leading to sluggish behaviour. The present study combined these two independent stressors of ion and water homeostasis, in order to investigate the role of K(+)- and water-balance during recovery from chill coma, in the chill sensitive insect L. migratoria. We confirmed that cold shock elicits a fast increase in haemolymph [K(+)] which is likely caused by a water shift from the haemolymph to the muscles and other tissues. Recovery of haemolymph [K(+)] is however not only reliant on recovery of haemolymph volume, as the recovery of water and K(+) is decoupled. Chill coma recovery time, after 2h at -4 °C, differed significantly between fasted animals and those fed on high K(+) diet. This difference was not associated with an increased disturbance of haemolymph [K(+)] in the fed animals, instead it was associated with a slowed recovery of muscle [K(+)], muslce water, haemolymph [Na(+)] and K(+)equilibrium potential in the fed animals.
Zoophysiology, Department of Bioscience, Aarhus University, C.F. Møllers Alle 3, Building 1131, DK-8000 Aarhus C, Denmark. Electronic address: jonas.andersen@biology.au.dk.
Jonas Lembcke
JL
Andersen
Anders
A
Findsen
Johannes
J
Overgaard
D000818:Animals; D003080:Cold Temperature; D058639:Cold-Shock Response; D004032:Diet; D005260:Female; D006458:Hemolymph / Q000378:metabolism*; D048188:Locusta migratoria / Q000502:physiology*; D008297:Male; D011188:Potassium / Q000378:metabolism*; D014882:Water-Electrolyte Balance
D011188:Potassium
Cold coma; Cold tolerance; Ion transport; Nernst potential; Sodium balance; Stress resistance