Defensive Strategies of Puerto Rican Dwarf Geckos (Sphaerodactylus macrolepis) Against Invasive Fire Ants

Invasive species present challenges to native organisms and offer unique opportunities to examine adaptations to novel stressors. We studied behavioral responses to invasive Red Imported Fire Ants (Solenopsis invicta) in native Puerto Rican Dwarf Geckos (Sphaerodactylus macrolepis) on Guana Island, British Virgin Islands. Geckos were exposed to no fire ants, few fire ants, or many fire ants. Solenopsis invicta was aggressive toward the geckos and the foraging ants frequently stung Dwarf Geckos, even when far from the mound. Dwarf Geckos displayed an array of anti-ant behaviors including consuming fire ants, flicking ants away with their limbs and/or tail, and rapidly fleeing attacking ants. These behaviors were elicited more frequently when more fire ants were encountered. Despite being stung often and by as many as nine fire ants, none of the tiny geckos died. Future research could usefully explore potentially delayed effects of fire ant envenomation and the impacts of fire ants on these geckos via egg predation or competition for invertebrate prey.