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Overwintering strategies are important in the survival of insects , and one such strategy involves the regulation of temperatures at which they freeze . Although all insects exhibit some degree of cold tolerance , they can generally be classified as either freeze tolerant or intolerant . Many freeze -intolerant insects seasonally depress their supercooling points , thereby increasing their cold -hardiness in preparation for winter . This study was conducted to assess the influence of cold acclimation on the supercooling ability of the red imported fire ant , Solenopsis invicta Buren . Colonies were consecutively exposed for seven days to decreasing temperatures of 10° , 5° , and O^C (treatments ) . At the end of each seven -day interval , a thermocouple probe was used to determine whole body supercooling points of randomly selected worker ants from each colony . In addition , head capsule widths and whole body weights were measured . Analysis of variance indicated a significant difference among supercooling points and acclimation temperatures (£ < 0 .05 ) .
In the 1970's , ice -nucleating active bacteria , a new category of biological ice -nucleators , were discovered among other epiphytic bacteria living on the surface of plants . These ice -nucleating bacteria have the capacity to catalyze ice formation at - 1° to -2°C . I therefore studied the effects of topical mist application of the ice -nucleating active bacteria Pseudomonas syringae (American Type Culture Collection 39254 ) on the freezing point of minor and media worker ants . My results showed that treatment with P . syringae increased the temperature at which the red imported fire ant froze , thus decreasing its supercooling ability (NOVA ; P < 0 .05 ) . |
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