M.Sc Thesis

M.Sc StudentFederman Roy
SubjectPotential Distribution and Monitoring of the Invasive
Species "The Little Fire Ant" (Wasmannia
DepartmentDepartment of Civil and Environmental Engineering
Supervisor PROF. Yohay Carmel


The Little Fire Ant (Wasmannia auropunctata) is an invasive species that originates in South and Central America and is among the 100 most damaging invasive species as defined by the IUCN. Over the past century, this species invaded many areas around the world, including Israel. The main objectives of this study are to predict W. auropunctata potential distribution at the global and local scales and to improve the monitoring method of this species. W. auropunctata's potential distribution was predicted using a model for species distribution called MAXENT. Model input included species location records within the native range and climatic variables. Model output is a map of the potential of establishment in each pixel relative to other pixels within the model extent. Invasive records were used to evaluate the performance of the models. Climate variables were obtained from online datasets. These datasets do not account for water input due to irrigation. I corrected this gap by adjusting precipitation data to express actual water input in these areas. This correction improved the performance of the global and local models, demonstrating the importance of water input in determining the distribution of this species. The global model prediction improved in five different geographical regions; a result which demonstrates the importance of irrigation correction for various geographical and climatic regions. The local model predicted high establishment potential in irrigated lands within the Mediterranean zone. Currently, the species does not utilize the full range of its potential niche in Israel, and is expected to further spread, mainly into irrigated lands. This study also sought to improve monitoring within Israel by defining the optimal survey methodology in this region. Current methods, which include bait placement and direct searching, were tested using field observations and experiments. The following parameters were tested: bait density, microclimate conditions at occupied bait locations and optimal weather conditions for performing surveys. In addition, I compared the efficiency of the bait and direct search methods. Direct searching was found the more efficient monitoring method for sites with known infestation. For discovering new infestations, I recommend direct searches in combination with baits placed in locations that humans can not effectively observe, at 1m intervals. By identifying areas of high W. auropunctata establishment potential and improving current monitoring methodologies, this study allows managers to more effectively monitor and prevent the spread of this invasive species.