Invasive species being introduced to a non-native environment is a growing and ongoing concern. The impact of these species can have a wide variety of effects on the native species, including behavioral and physical alterations.
Tylan et al., researchers at Penn State University, explored the impact of the invasive species red imported fire ants (Solenopsis invicta) on native eastern fence lizards (Sceloporus undulatus). This is an especially unique relationship as the fire ants serve as predators of the lizards (the ants can lift the lizard scales and induce death by stinging with poisonous venom) and prey (lizards can use the fire ants as a food source).
In this study, the team wanted to understand if the consumption of fire ants helped to protect the lizards against future fire ant stings. To do this, they collected lizards from a region where fire ants had not invaded and created three control groups; fed, sting, and control. Lizards in the control group were handled similarly to lizards in each group but were fed dead ants or exposed to live ants. The fed group was fed ten dead fire ants 3x per week for three weeks. The sting group was exposed to stings from up to 10 live fire ants 3x per week for three weeks.
The team measured white blood cell ratios, phagocyte respiratory burst activity, lymphocytic cell-mediated immunity, anti-fire ant IGM, natural antibodies, and complement activity to measure the immune response. The team also used the Arbor Assays Corticosterone ELISA Kit (K014-H) to assess stress in the lizards.
In summary, the team found good evidence to support the hypothesis that the consumption of fire ants elicited an immune response that could help protect the lizard against future fire ant stings.