Aversion learning in response to an invasive venomous prey depends on stimulus strength
Learned avoidance can allow animals to survive the introduction of noxious prey. The effectiveness of aversion learning can depend on the intensity of the stimulus. The red imported fire ant, Solenopsis invicta, is a novel prey of the eastern fence lizard, Sceloporus undulatus, but can prove lethal especially to juvenile fence lizards. Thus, avoiding consumption of fire ants would increase survival for juveniles. We tested whether juvenile lizards would exhibit learned aversion of fire ants, and whether aversion would be longer lasting following exposure to greater numbers of fire ants. Lizards were exposed to one of three 8-ant treatments with varying relative proportions of fire ants for 5 days: (1) 100% fire ants, (2) 50% fire ants and 50% native ants, and (3) 0% fire ants (8 native ants). Juveniles in the 100% fire ant treatment showed clear aversion learning, consuming nearly two-thirds fewer fire ants after the first trial day. Juveniles exposed to the 50% fire ant treatment, consumed slightly fewer fire ants after day 1 of the trial, but recovered by day 5. Juveniles that received native ants only did not alter their consumption of ants over time. These results suggest that juveniles show species-specific aversion to fire ants, but this was dependent upon stimulus strength. When presented with both fire ants and native ants, lizards reduced their consumption of both species. Investigating whether exposure to noxious invasive prey alters the consumption of native prey would provide insight into long-term impacts of invasive species.
KeywordsAvoidance Behavior Invasive prey Fire ant Lizard Plasticity
The authors thank K. MacLeod, D. Ensminger, and N. Freidenfelds for their assistance in the field, the Langkilde lab members for feedback on the project, and Joel Martin and the staff of the Solon Dixon Forestry Education Center for logistical support. The Pennsylvania State University Animal Care and Use Committee approved all experimental procedures, and the respective States permitted animal collection. This research was funded in part by the National Science Foundation (IOS 1456655; to TL).
- Brower LP, Brower JVZ (1964) Birds, butterflies and plant poisons: a study in ecological chemistry. Zool N Y 49:137–159Google Scholar
- Buren WF (1972) Revisionary studies on the taxonomy of the imported fire ants. J Ga Entomol Soc 7:1–26Google Scholar
- Davis TS (2005) Pyramid ants. South Carolina State Documents Depository. http://hdl.handle.net/10827/10994. Accessed 25 July 2018
- Freidenfelds NA, Langkilde T (2009) Natural history notes: Sceloporus undulatus (eastern fence lizard) diet. Herpetol Rev 40:439Google Scholar
- Garcia J, Lasiter PS, Bermudez-Rattoni F, Deems DA (1985) A general theory of aversion learning. Ann N Y Acad Sci 443:8–21. https://doi.org/10.1111/j.1749-6632.1985.tb27060.x CrossRefGoogle Scholar
- Holmes RA, Gibson RN (1986) Visual cues determining prey selection by the turbot, Scophthalmus maximus L. J Fish Biol 29:49–58. https://doi.org/10.1111/j.1095-8649.1986.tb04998.x CrossRefGoogle Scholar
- Markin GP, O’Neal J, Dillier J (1975) Foraging tunnels of the red imported fire ant, Solenopsis invicta (Hymenoptera: Formicidae). J Kansas Entomol Soc 1975:83–89Google Scholar
- Rozin P, Zellner D (1985) The role of Pavlovian conditioning in the acquisition of food likes and dislikes. Ann N Y Acad Sci 443:189–202. https://doi.org/10.1111/j.1749-6632.1985.tb27073.x CrossRefGoogle Scholar
- Tingley R, Ward-Fear G, Schwarzkopf L, Greenlees MJ, Phillips BL, Brown G, Strive T (2017) New weapons in the Toad Toolkit: a review of methods to control and mitigate the biodiversity impacts of invasive cane toads (Rhinella marina). Q Rev Biol 92:123–149. https://doi.org/10.1086/692167 CrossRefGoogle Scholar
- Vitousek PM, D’Antonio CM, Loope LL, Westbrooks R (1996) Biological invasions as global environmental change. Am Sci 84:468Google Scholar