POTENTIAL OF ICE-NUCLEATING ACTIVE BACTERIA FOR MANAGEMENT OF THE REDIMPORTED FIRE ANT (HYMENOPTERA, FORMICIDAE)

Overwintering strategies are important in the survival of insects, and one such strategy involves tile regulation of temperatures at which t hey freeze. Although all insects exhibit some degree of cold tolerance , they can generally be classified as either freeze tolerant or intole rant. Many freeze-intolerant insects seasonally depress their supercoo ling points, thereby increasing their cold-hardiness in preparation fo r winter This study was conducted to assess the influence of cold accl imation on the supercooling ability of the red imported fire ant, Sole nopsis invicta Buren. Colonies were consecutively exposed for 7 d each to decreasing temperatures of 10, 5, and 0 degrees C. At the end of e ach 7-d interval, a thermocouple probe was used to determine whole bod y supercooling points of randomly selected worker ants from each colon y. Analysis of variance indicated a significant difference among super cooling points and acclimation temperatures. In the 1970s, ice-nucleat ing active bacteria, a new category of biological ice-nucleators, were discovered among other epiphytic bacteria living on the surface of pl ants. These ice-nucleating bacteria have the capacity to catalyze ice formation at -1 to -2 degrees C. Mie investigated the effects of topic al mist application of the ice-nucleating active bacteria Pseudomonas syringae on the freezing point of minor and media worker ants. Treatme nt with P. syringae increased the temperature at which the red importe d fire ant froze, thus decreasing its supercooling ability.