Abstract
Solenopsis invicta and Solenopsis richteri are two very closely related invasive ant species; however, S. invicta is a much more successful invader. Physiological tolerance to abiotic stress has been hypothesized to be important to the success of an invasive species. In this study, we tested the hypothesis that S. invicta is more tolerant to heat and desiccation stress than S. richteri. The data strongly support our hypothesis. S. invicta was found to be significantly less vulnerable than S. richteri to both heat and desiccation stress. Despite S. richteri having significantly higher body water content, S. invicta was less sensitive to desiccation stress due to its significantly lower water loss rate (higher desiccation resistance). After the cuticular lipid was removed, S. invicta still had a significantly lower water loss rate than S. richteri, indicating that cuticular lipids were not the only factors accounting for difference in the desiccation resistance between these two species. Since multiple biological and/or ecological traits can contribute to the invasion success of a particular species, whether the observed difference in tolerance to heat and desiccation stresses is indeed associated with the variation in invasion success between these two species can only be confirmed by further extensive comparative study.
Highlights
The red imported fire ant, Solenopsis invicta, is one of the most successful invasive ants in the world, and is included in the 100 of the World’s Worst Invasive Alien Species [1].Native to South America, S. invicta has been introduced into many countries and regions, including the United States, Australia, China, Philippines, Thailand, Taiwan, Hong Kong, Macau and etc., [2] and has a great potential to spread further [3]
Mortality Under Heat Stress At 25uC, there was no significant difference in mortality among large red imported fire ant (LR), small red imported fire ants (SR); large black imported fire ant (LB), and small black imported fire ant (SB)
The higher water loss rate might cause S. richteri to survive significantly shorter than S. invicta under the same desiccation stress
Summary
The red imported fire ant, Solenopsis invicta, is one of the most successful invasive ants in the world, and is included in the 100 of the World’s Worst Invasive Alien Species [1].Native to South America, S. invicta has been introduced into many countries and regions, including the United States, Australia, China, Philippines, Thailand, Taiwan, Hong Kong, Macau and etc., [2] and has a great potential to spread further [3]. The red imported fire ant, Solenopsis invicta, is one of the most successful invasive ants in the world, and is included in the 100 of the World’s Worst Invasive Alien Species [1]. The black imported fire ant, Solenopsis richteri, a closely related species to S. invicta [4], is an invasive ant but with much less success. S. richteri has established only in the southern United States outside its native range. Both ants invaded the United States through the same entrance: the port of Mobile, Alabama [5]. S. richteri is confined to a relatively small area along the northern boundary of S. invicta’s distribution range, including northern Alabama, north Mississippi and southern Tennessee [5,7,8]
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