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Survival of Boll Weevils Exposed to Freezing Temperatures with and Without Ice Nucleators

Clyde E. Sorenson, Milon George


We assessed the impact of the presence of ice on the survival of over-wintering boll weevils (Anthonomus grandis grandis Bohman) through two sets of experiments. In the first, groups of weevils were exposed to three sub-freezing temperatures (-3.9, -7.0, and -9.4°C) for six hours either with or without free water present. Water was provided by sandwiching the weevils between two layers of wet cotton cloth. Whenever freezing of the water in the cloth took place, boll weevil survival was very low, regardless of tempera-ture. In the second set of experiments, the freezing points of individual weevils were determined with or without free water present. Dry weevils froze at temperatures between -4° and -18°C (mean =14.49°C); wet weevils froze essentially simultaneously with the free water present with them. Weevils that froze expired. No difference between the freezing points of trap-caught and square raised weevils were detected. These observations may help explain the distribution of boll weevils in the Missouri Bootheel.

Reprinted from Proceedings of the 1996 Beltwide Cotton Conferences pp. 969 - 972
©National Cotton Council, Memphis TN

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Document last modified Sunday, Dec 6 1998