Ant Wars: Can Native and Invasive Ants Coexist?
Ants are among the most abundant organisms on earth, with a recent estimate placing their number around 20 quadrillion individuals and their biomass around 20% of human biomass. They play key roles in ecosystems around the world, contributing to seed dispersal, soil aeration and nutrient cycling. However, invasive ants such as the Argentine Ant are giving a bad rap to ants in general by invading people's homes and also causing major crop damage. Worse, such invasive ants often create cooperative super-colonies that spread over hundreds of miles, driving out native ant species within their range. Despite well-established evidence that Argentine ants are harming native harvester ant populations across California, here at our Bernard Field Station Argentine ants and native harvester ants seem to be coexisting, even though frequent interactions have been observed. What allows this population of harvester ants to resist Argentine ant invasion?
Project 1: Assessing colony nest defense. We are monitoring the activity of harvester ants around the nest entrance via weekly visits and field cameras programmed to take short videos throughout the day. Do they show defensive or evasive behaviors such as moving the nest entrance, maintaining multiple nest entrances, or changing the daily schedule of opening and closing the nest? How are these behaviors impacted by local climate conditions and the presence of Argentine ants?
Project 2: Testing for chemical eavesdropping. If harvester ant colonies are avoiding Argentine ants, how do they detect them? One possibility is by eavesdropping: detecting the chemicals the Argentine ants use to create their massive trails. To test for this, we have isolated some of the chemicals specific to Argentine ant trails and will present these to individual harvester ants in a small custom-built choice arena.
Such behavioral defenses could explain how our local population of harvester ants has managed to persist despite Argentine ant invasion. This ongoing project will set the stage for a larger collaborative study aimed at predicting how the triple threat of species invasion, climate change, and increasing urbanization will shape the community of native harvester ants and the plants that depend on them across Southern California.
Students working on this project will (1) observe and document native harvester ant colonies at the Bernard Field Station, (2) perform experiments assessing harvester ant response to Argentine ant presence in the field, (3) analyze data and videos from field experiments using a combination of manual and automated methods, and (4) statistically analyze and present the results in visual and written form.
You will be part of a team of students working on an interdisciplinary project, using biology, chemistry, computation and engineering to solve problems of biological and applied conservation interest. You'll also have the opportunity to spend lots of time outdoors, observing nature. The variety of techniques and approaches will give you an opportunity to explore your interests and develop new skills. This is a new project, currently developing collaborations with researchers at nearby universities including UC San Diego and UC Riverside, which could expand your professional network. There may be opportunities to continue the work in a senior thesis, present at a regional or national conference, and/or co-author future publications stemming from ongoing work.