TY - JOUR
T1 - Low temperature acclimated populations of the grain aphid Sitobion avenae retain ability to rapidly cold harden with enhanced fitness
AU - Powell, SJ
AU - Bale, Jeffrey
PY - 2005/1/1
Y1 - 2005/1/1
N2 - contrast to previous studies of rapid cold-hardening (RCH), which have investigated the responses of insects maintained under 'summer conditions' (20 degrees to 25 degrees C), this study focuses on the ability of low-temperature acclimated insects to undergo RCH. When the grain aphid Sitobion avenae Fabricus was low-temperature acclimated by rearing for three generations at 10 degrees C, the discriminating temperatures (temperature that results in approximately 20% survival after direct transfer from the rearing temperature to a sub-zero temperature for a period of 3 h), of first instar nymphs and adult aphids were -11.5 degrees and -12 degrees C, respectively. Maximum rapid cold-hardening was induced by cooling aphids at 0 degrees C for 2 h (nymphs) or 30 min (adults), resulting in survival at the respective discriminating temperatures increasing from 26% to 96% (nymphs) and 22% to 70% (adults). Cooling from 10 degrees to 0 degrees C at 1 degrees, 0.1 degrees and 0.05 degrees C min(-1) significantly increased survival of nymphs at the discriminating temperature, but not of adults. There were no 'ecological costs' associated with rapid cold-hardening at 0 degrees C, or with exposure of rapidly cold-hardened aphids to the discriminating temperatures; fecundity and longevity, in both nymphs and adults were either similar to control aphids or significantly increased. The study demonstrates that rapid cold-hardening ability is retained in aphids that have already undergone cold-acclimation, as would be the case in overwintering aphids. Both rapid cold-hardening and subsequent exposure at previously lethal temperatures can enhance fitness in surviving individuals.
AB - contrast to previous studies of rapid cold-hardening (RCH), which have investigated the responses of insects maintained under 'summer conditions' (20 degrees to 25 degrees C), this study focuses on the ability of low-temperature acclimated insects to undergo RCH. When the grain aphid Sitobion avenae Fabricus was low-temperature acclimated by rearing for three generations at 10 degrees C, the discriminating temperatures (temperature that results in approximately 20% survival after direct transfer from the rearing temperature to a sub-zero temperature for a period of 3 h), of first instar nymphs and adult aphids were -11.5 degrees and -12 degrees C, respectively. Maximum rapid cold-hardening was induced by cooling aphids at 0 degrees C for 2 h (nymphs) or 30 min (adults), resulting in survival at the respective discriminating temperatures increasing from 26% to 96% (nymphs) and 22% to 70% (adults). Cooling from 10 degrees to 0 degrees C at 1 degrees, 0.1 degrees and 0.05 degrees C min(-1) significantly increased survival of nymphs at the discriminating temperature, but not of adults. There were no 'ecological costs' associated with rapid cold-hardening at 0 degrees C, or with exposure of rapidly cold-hardened aphids to the discriminating temperatures; fecundity and longevity, in both nymphs and adults were either similar to control aphids or significantly increased. The study demonstrates that rapid cold-hardening ability is retained in aphids that have already undergone cold-acclimation, as would be the case in overwintering aphids. Both rapid cold-hardening and subsequent exposure at previously lethal temperatures can enhance fitness in surviving individuals.
KW - aphid
KW - fitness
KW - Sitobion avenae
KW - seasonal acclimation
KW - rapid cold-hardening
UR - http://www.scopus.com/inward/record.url?scp=23144431969&partnerID=8YFLogxK
U2 - 10.1242/jeb.01685
DO - 10.1242/jeb.01685
M3 - Article
C2 - 15961747
VL - 208
SP - 2615
EP - 2620
JO - Journal of Experimental Biology
JF - Journal of Experimental Biology
IS - 13
ER -