Toxicity and Behavioral Responses to Commercial Pesticide Formulations and Natural Products in the Arizona Bark Scorpion, Centruroides sculpturatus (Scorpiones: Buthidae)

Arizona bark scorpions (Centruroides sculpturatus, Ewing) are a medically significant species with frequent human interactions. Despite residential pesticide application being common practice in the American Southwest, there are few studies evaluating the effects of common pesticide formulations on scorpion mortality and behavior. We compared three commercial pesticide formulations (pyrethroid, pyrethroid + synergist, pyrethroid + neonicotinoid + synergist) using direct scorpion application. We also investigated behavioral responses associated with cedarwood essential oil, lavender essential oil, and dried chrysanthemums. There was no difference in knockdown between the three pesticides using direct application, with all scorpions incapacitated within 60 min. Crossing of a treated strip increased following exposure to prallethrin + esfenvalerate + synergist and cedarwood oil, whereas fewer crossings occurred with lavender oil exposure. Compounds in lavender may have scorpion-repellent properties, while the greater number of crossings for the prallethrin formulation may reflect insecticide-induced behavioral excito-repellency or irritancy. Further research should determine how these findings translate to scorpion control under field conditions, including the relative contributions of knockdown, mortality and behavioral responses following peridomestic pesticide treatment.