Thursday, 3 August 2006 - 7:00 PM
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Unicoloniality in the little fire ant Wasmannia auropunctata in Israel

Merav Vonshak, Tamar Dayan, and Abraham Hefetz. Department of Zoology, Tel Aviv University, Tel Aviv, 69978, Israel

Unicoloniality is thought to be one of the major attributes that make invasive ants so successful. Ants from different nests mix freely and lack intraspecific aggression, while maintaining high interspecific aggression. The little fire ant (Wasmannia auropunctata) was recently discovered in Israel, the first record of its invasion to the Middle East. We believe that the ants were imported from Gabon (where they are invasive as well) 5-8 years ago to the Jordan Valley region in the north of Israel, on imported logs. It is not yet known whether a single or several importations account for their establishment. A preliminary survey showed that the village to which the logs were imported is the center of infestation, from which they dispersed to the neighboring villages.

 

In order to test whether the ants form supercolonies we sampled colonies from various localities and measured their intra-and interspecific aggression as well as intra-colony variations in cuticular hydrocarbon profiles. Preliminary chemical analyses followed by principle components analysis showed that nests from different localities possess distinctive profiles. However, using a group encounter paradigm for assessing the ants’ aggression, the ants didn’t show intraspecific aggression even when nests from extremes of their local distribution were tested. Interspecific aggression was ubiquitously high and generally culminated in the heterospecific ants’ death. It is still not clear whether W. auropunctata form supercolonies in Israel, as it is known to form in other countries of its invasive range. Preliminary observations suggest that where the little fire ant density is high, no other ant species are present, while in areas of low density or no fire ants, up to 15 other ant species occur; we are currently analyzing ant community structure in a gradient of little fire ant densities.

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