PARENT SESSION
WP9 - Immunotoxicity
Chair: Rice, Charles¹, ¹ Clemson University, Pendleton, SC
2:10 PM to 5:30 PM - Wednesday, 20 November 2002
Room Ballroom E

(639) Effects of subchronic dietary deltamethrin exposure on the immune system of tiger salamanders.

Froese, Jennifer^*,1, Smits, Judit¹, Forsyth, Doug², Wickstrom, Mark¹, ¹ University of Saskatchewan, Saskatoon, Saskatchewan, Canada² Canadian Wildlife Service, Saskatoon, Saskatchewan, Canada

ABSTRACT- One of the theories to explain recent global declines in amphibian populations involves contaminant-induced immune alteration, with subsequent increases in infectious diseases. The objective of this study was to determine whether deltamethrin, a pyrethroid insecticide with widespread agricultural use, affects the immune system of tiger salamanders (Ambystoma tigrinum), a widely distributed species whose range encompasses the Canadian prairie agricultural region. Wild-caught tiger salamanders were divided among four treatment groups (vehicle control, or deltamethrin at 4, 40, or 400 g/kg/day), and were dosed via the diet three times per week for four weeks. The potential effects of pesticide exposure on immune function were evaluated by examining mass and histopathology of immune system organs, haematological variables, and assays of lymphoblastic transformation, functional phagocytosis, and oxidative burst. Dietary deltamethrin exposure significantly affected liver mass and packed cell volume, but kidney mass, spleen mass, plasma protein and circulating leukocyte populations were unaffected. In addition, there were no statistically significant differences between treatment groups with regard to lymphoblastic transformation, phagocytosis, or oxidative burst. The results of this study suggest that deltamethrin is not immunotoxic to tiger salamanders, and it is unlikely that exposure to environmentally relevant concentrations of deltamethrin has contributed to the recent emergence of iridovirus outbreaks in tiger salamander populations.

Key words: immunotoxicity, amphibian, pesticide, deltamethrin