PT11 Contaminant Bioavailability
Exhibit Hall
8:00 AM - Tuesday, 11 November 2003
(PT182) Developmental effects and toxicity of four selenium species to a terrestrial insect detritivore.
Jensen, P.1, Rivas, M.1, Trumble, J.1, 1 University of California, Riverside, CA, USA
ABSTRACT- Megaselia scalaris (Loew)(Diptera: Phoridae) is a ubiquitous terrestrial detritivore that consumes both animal and plant material. Because both plants and animals convert selenium pollutants into various forms, the relative toxicities of ecologically relevant concentrations (0.5 
g/g up to 800 g/g) of sodium selenate, sodium selenite, seleno-L-methionine, and Se-(Methyl) selenocysteine hydrochloride to larvae were assessed in diet bioassays. In addition, ovipositional preferences of female adults and developmental effects on the eggs and larvae were measured. Selenocysteine was the most toxic of the selenium species to the larvae, followed by seleno-L-methionine, selenate, and selenite. Indicating a lack of avoidance behavior, ovipositing females did not discriminate between the highest treatment concentrations of any of the pollutants as compared to the controls. Larval development time was significantly increased with exposure to each of the forms of selenium. Pupal development was not affected by any of the selenium treatments. Significant differences between male and female adult eclosion times were observed, with females eclosing later than males as selenium concentrations increased. All four compounds also caused significant decreases in larval survival relative to controls. The population level implications of lack of avoidance of contaminated food, and the potential effects of increased development times, reduced survivorship, and non-synchronized male and female emergence are addressed.
Key words: insect, Megaselia scalaris, seleno-L-methionine, selenocysteine