Biochemistry and physiology of aestivo-hibernation in the adult apple blossom weevil, Anthonomus pomorum (Coleoptera: Curculionidae)
1996
Kostal, V. | Simek, P.
Changes in supercooling capacity, cold hardiness (survival of subzero temperatures), water content, dry weight, and content of low molecular weight sugars and alcohols in the course of aestivo-hibernation are described in the apple blossom weevil, Anthonomus pomorum. The supercooling point (SCP) was high (-11 degrees C) in feeding beetles, dropped to about-20 degrees C after the transition to aestivo-hibernation and remained stable until the start of feeding in the next spring. A high capacity to survive very low temperatures (-18 degrees C) for a short time (1 day) developed concomitantly with the transition from summer feeding to aestivo-hibernation. The capacity to survive very low temperatures for a longer time (5 days) developed later, after the onset of low temperatures during autumn. Transfer of aestivating beetles to low temperatures for 14 days resulted in cold acclimation and increased cold hardiness. The seasonal dynamics of trehalose content [peaking on 15.0 +/- 6.4 microgram/mg dry weight (mean +/- SD) during December] and cold hardiness showed similar courses. Cold-acclimated beetles had elevated content of trehalose too. Aestivating beetles had a very low capacity to tolerate desiccating conditions. Low relative air humidity and inaccessibility of water for drinking led to rapid depletion of body water and high mortality. Those beetles which survived in desiccating experiments had higher initial dry weight and higher initial (and/or elevated) content of trehalose.
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