Effects of Low Temperature on the Survival of the Alfalfa Weevil from Alberta and Utah1

Publisher Website
Google Scholar
Abstract
Alfalfa weevils, Hypera postica (Gyll.), were collected from Alberta and Utah in the spring of 1957. Their progenies were reared for one generation under indentical conditions in the laboratory and the adults of the two populations were compared for mortality at low temperatures. The two groups did not differ in their undercooling points, which averaged about - 18° C. After 72 days of exposure to -10° C. there was no difference in mortality between the Alberta and Utah weevils. However, when moved to 10° C. after 11 days at -10° C. the Utah weevils became active much sooner than the Alberta weevils. Alberta and Utah weevils were compared for mortality in the field during the winter of 1957-58 in southern Alberta. In one experiment the weevils were allowed to select their own habitat. In a second experiment they were restricted to four positions. In both experiments there were no significant differences in mortality between the two groups of weevils. It was concluded that the establishment of the alfalfa weevil in more northerly regions did not arise through development of increased cold resistance but, perhaps, through a selection of those individuals that possess slower responses to rising temperatures.

This publication has 2 references indexed in Scilit: