Meeting Abstract

P3.160A  Sunday, Jan. 6  Why do grasshopper mice prefer stripe-tailed scorpions over bark scorpions? Testing the “ouch” vs. “super-size me” hypotheses. NIERMANN, C*; TATE, T; ROWE, A; ROWE, M; , ; , ; , ; , ; , ; , ; , ; , ; Sam Houston State; Sam Houston State; Univ. Texas, Austin; Sam Houston State crystal.niermann@gmail.com

Grasshopper mice (Onychomys spp.) are voracious predators on arthropods, including scorpions. While several studies show that grasshopper mice readily attack and consume relatively harmless arachnids, including stripe-tailed scorpions (Vaejovis spp.), our results demonstrate that grasshopper mice are equally voracious in attacking and consuming bark scorpions (Centruroides spp.), a genus possessing extremely painful stings containing potentially lethal, vertebrate-specific neurotoxins. The mice are completely resistant to the lethal components in bark scorpion venom, but only partially resistant to the venom constituents that cause intense pain; thus, it is perhaps not surprising that grasshopper mice preferentially attack a stripe-tailed scorpion when presented simultaneously with a bark scorpion. While we assume this preference is driven by the more painful sting delivered by bark scorpions (the “ouch” hypothesis), this interpretation is confounded by the larger average body mass of stripe-tailed scorpions. In short, grasshopper mice may simply prefer a half-pound hamburger to a quarter-pounder (the “super-size me” hypothesis). To distinguish between these two competing hypotheses, we are repeating our original choice tests with a simple modification; this time, bark scorpions will have their aculeus (stinger) blocked with a small bead of epoxy, preventing stinger penetration of the mouse’s integument and, thus, eliminating envenomation. The “super-size me” hypothesis would be supported over the “ouch” hypothesis if mice still prefer a stripe-tailed scorpion to a bark scorpion even when the latter can no longer inflict a painful sting.