Behavioral evidence of pheromonal signaling in desert grassland scorpions Paruroctonus utahensis

Abstract Behavioral evidence suggests that, in some scorpion species, females deposit a pheromone that attracts mates. To date, however, no pheromone has been identified. The goal of our study was to isolate a pheromone from female desert grassland scorpions, Paruroctonus utahensis (Williams, 1968) (Scorpiones:Vaejovidae). We took in situ cuticular washes from female P. utahensis in a chloroform-methanol solution; the extract stratified into aqueous and organic layers. In controlled laboratory experiments, most males exposed to female extract (aqueous and organic fractions combined) exhibited pre-courtship behavior, whereas those exposed to the solvent control (2∶1 chloroform-methanol) showed no change in behavior. When extract fractions were separately tested, males initiated pre-courtship behavior when exposed to the organic fraction but not when exposed to the aqueous fraction. These data are the first experimental evidence of a female pheromone in this species and are important early steps toward characterizing any scorpion pheromone.