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Temperature Dependence of Boll Weevil, Anthonomus grandis, Host-Free Survival

Dale W. Spurgeon


ABSTRACT

Most studies of boll weevil overwinter survival have focused on the effects of severe winter temperatures. Consequently, little is known regarding the temperature dependence of such survival in locales where sub-freezing temperatures infrequently occur. The temperature dependence of host-free survival of diapausing weevils was examined at four constant temperatures ranging from 12.8 to 29.4ºC. No differences in survival were detected between weevil sexes. Significant influences of temperature on survival were observed, but these relationships changed over the course of the survival period. Survival was consistently lowest at 29.4ºC. Survival rates at 12.8 and 18.3ºC were initially higher than those at 23.9ºC, but after the 20th week survival at 12.8 and 23.9ºC were similar. From week 21 until week 40, when the numbers of live weevils remaining were low for all temperatures, survival at 18.3ºC remained higher than survival at other temperatures. The lower- than-expected survival at 12.8ºC suggests the occurrence of a chronic low-temperature injury not previously recognized. These results provide additional insight into the dynamics of boll weevil overwintering and should be useful in developing models to predict weevil survival in areas where sub-freezing temperatures seldom occur.





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Document last modified May 20, 2002