ESQUIVEL, J.*; TUBERTY, S.R.; MOORE, J.A.; DUUS, M.; CAMPANY, C.; JONES, M.; Appalachian State University, Boone, NC.: Ecdysteroid titer and characterization during the first instar intermolt of the scorpion, Centruroides vittatus.

Ecdysteroids (Ec) play a crucial role as the regulatory steroid molting hormone in arthropods and have been isolated from many insect and crustacean species, but only a few arachnids (e.g., ticks). Quantification and characterization of Ec in arachnids such as scorpions will increase our understanding of basal arthropod endocrinology and may aid assessment of detrimental effects of xenobiotics in the environment. Conjugated Ec have been characterized and reportedly function as storage (apolar) or in the excretion (polar) of Ec. Separation of conjugates from free Ec during isolation and quantification is necessary in order to determine functional patterns during ecdysis. Centruroides vittatus scorpions belong to the family Buthidae which is the most widely distributed group of scorpions, occurring in both old world and new world populations. C. vittatus embryos develop inside the female and receive nutrients and Ec from yolk reserves that last through parturition and the first instar. Following parturition, young climb onto the carapace where they spend the duration of their first instar, dispersing from the female a few days after their first molt. First instars were subsampled from parturition to first molt, Ec were extracted, conjugates were enzymatically hydrolyzed, and resulting free Ec was quantified with an EIA for 20-hydroxyecdysone. Further characterization of free and conjugated ecdysteroids is currently underway. Apolar Ec levels were high early and late in the molt cycle, free Ec peaked shortly before molt, and polar Ec were negligible throughout ecdysis. Scorpions have several adaptations for reducing water loss, therefore we hypothesize that hydrophobic apolar Ec used in excretion pathways are adaptive for desert arthropods.