EFFECTS OF LOW-TEMPERATURE ON THE ARCTIC APHID ACYRTHOSIPHON-BREVICORNE

1. Summer generations of the Arctic aphid Acyrthosiphon brevicorne experience subzero temperatures that would be lethal or cause sub-lethal effects in both summer and winter populations of temperate aphids. 2. The LT50 temperatures for 3 h exposures of nymphs and adults of A. brevicorne (-9 to - 10-degrees-C) are similar to 1 min exposures in temperate species. 3. The sexual morphs (oviparae and males) which occur towards the end of summer are more cold hardy than the viviparae. 4. Cold exposure had no effect on the rate of development of first-instar nymphs that survived -5, -10 or -12.5-degrees-C for 3 h. There was no reduction in daily reproduction, length of reproductive lifetime or total fecundity in viviparae that survived exposure as first-instar nymphs at -5 or -10-degrees-C for 3 h. 5. Daily reproduction and longevity of viviparae cooled as adults were not affected by exposure to -5 or -7-degrees-C for 3 h but at -10-degrees-C there was a significant reduction in reproductive lifetime thus reducing total fecundity. 6. The active stages of the Arctic aphid A. brevicorne are more cold hardy than their temperate counterparts.