Argentine ants, honeydew, and trees

NSF Fellow: Gabi Welch, College of Coastal Georgia

Mentor: Dr. Josh Gibson

Argentine ants are an invasive species of ant that outcompetes native ants in their territories. Their mutualism with honeydew-producing insects results in negative impacts to agriculture and plants. The hypothesis of this study is that due to the host-tree preferences of honeydew-producing insects, 1) Argentine ants are visiting some genera of trees more than others, and 2) they are collecting honeydew from some genera of trees more than others. The genera of trees I am focusing on are Quercus, Pinus, Acer, Lagerstoemia, and Taxodium. I will visually identify what trees on the Georgia Southern Statesboro campus Argentine ants are visiting. Trees will be scored with the presence or absence of Argentine ants. After establishing which trees the ants are using, I will be taking photographs of the ant trails on the trees and using an image analysis software (ImageJ) to measure the head to gaster ratio of ants moving up and down the tree. I will use a normalized gaster size to show whether ants are bringing honeydew from the tree back to their nest based on the direction they are moving. I will also use normalized gaster size to compare results across tree genera. I predict that I will observe a higher proportion of Argentine ants on some of these five genera than others and that I will observe a larger normalized gaster size in ants moving down trees versus those moving up. This gaster size difference will also vary across tree genera. The data obtained through this study can be used to inform landscaping decisions in order to minimize resources for Argentine ants to help control their population and to curb populations of homopteran pests.