MP2 Toxicity of Mixtures
255 Portland Ballroom
1:20 PM - 4:40 PM, Monday
() Selenium and Mercury mixtures: Toxicological and Developmental Effects on Two Insects at the Bottom of the Food Web.
Jensen, P.1, Trumble, J.1, 1 University of California at Riverside, Riverside, California, USA
ABSTRACT- Selenium and mercury are significant anthropogenic pollutants in the western United States. We investigated the individual effects of the most prominent forms of these pollutants on the bottom of the food web in two representative ecosystems. The primary test organisms were Megaselia scalaris, a terrestrial detritivore, and Culex quinquefasciatis, an aquatic filter feeder. For M. scalaris, we found an LC50 value of 258 
g/g (wet weight) for selenate. We also found that larval development time was significantly increased with exposure to selenate at 100 g/g and above, and that it affected the developmental rates differently in males and females. The LC50 value for methyl mercury was much lower for M. scalaris at 14 g/g. Larval development time was significantly increased at only 10 g/g, and puparial development time was also significantly increased at 20 g/g. However, methyl mercury did not affect the developmental rate of the sexes differently. For C. quinquefasciatis, we found an LC50 value of 11.8 g/g for selenate in addition to delays in development, with a significantly different Growth Index value at the lowest level tested (2 g/g). Methyl mercury affected C. quinquefasciatis at a much lower concentration, with an LC50 value of 46.42 g/kg, but did not cause any significant delays in developmental time. In addition to these results, joint toxicity data for the two toxicants are discussed.
Key words: mercury, selenium, insect, mixture