Meeting Abstract
P3.7 Sunday, Jan. 6 Do grasshopper mice actually eat noxious bark scorpions in the field? TATE, T*; JAROSZEWSKI, J; ROWE, A; ROWE, M; , ; , ; , ; , ; , ; , ; , ; , ; Sam Houston State; Appalachian State; Univ. Texas, Austin; Sam Houston State tgt007@shsu.edu
Grasshopper mice (Onychomys spp.) are voracious predators on arthropods, including scorpions, although work-to-date has examined only benign genera such as stripe-tailed scorpions (Vaejovis spp.). In many regions the mice are also sympatric with bark scorpions (Centruroides spp.), a genus possessing extremely painful stings containing potentially lethal, vertebrate-specific neurotoxins. Our studies show that grasshopper mice unhesitatingly attack and consume bark scorpions, protected by structural changes in the mice’s neurons and muscle cells that make them completely resistant to the venom components causing death, but only partially resistant to the venom components causing pain; these results may explain why grasshopper mice prefer to attack and consume a less painful stripe-tailed scorpion when presented simultaneously with a more painful bark scorpion. Here, we examine how the mice’s neurophysiological adaptations to bark scorpion venom may have influenced their predatory behavior in the field. We analyzed the fecal samples of 135 wild-caught grasshopper mice from 5 different populations variously sympatric or allopatric with bark scorpions (stripe-tailed scorpions were present at all 5 sites). Attempts using molecular techniques to identify prey species from scat were unsuccessful, as were efforts to identify prey from the finely masticated pieces deposited in the feces. Thus, we are using a dissecting scope with UV illumination to simply identify the presence or absence of scorpion exoskeleton in the feces of each mouse. When coupled with the geographic mosaic of the mice and scorpions, these data should nonetheless permit us to determine whether grasshopper mice avoid bark scorpions in locations where more palatable species of arachnids are also available.
