Effects of Dietary Selenium and Mercury on House Crickets (Acheta domesticus L.): Implications of Environmental Co-exposures
CARLA R. RALSTON, J. LLOYD BLACKWELL, III, AND NICHOLAS V.C. RALSTON
Energy & Environmental Research Center, University of North Dakota, Grand
Forks, North Dakota, USA
Department of Economics, University of North Dakota, Grand Forks, North Dakota, USA
Selenium (Se) availability is an indicator of susceptibility to mercury (Hg) bioaccumulation and toxicity, but the mechanisms and extents of these effects are not well characterized. Although the mechanism remains undefined, reducing MeHg accumulation in insects at the base of the food web may contribute to the effect. This study investigated interactive effects of dietary selenium (0.1, 0.3, 1.0, 3.0, and 10 m mol Se/kg) with either 0 or 50 m mol MeHg on growth and survival of house crickets (Acheta domesticus L.), an easily manipulated insect model. Poor survival and slower growth and development were seen in crickets fed high levels of MeHg with low selenium. Increased dietary selenium resulted in improved survival and increased weight gains in crickets fed MeHg. On the basis of biomass at the end of the 5 week study, the optimum selenium intake was 3 m mol Se/kg. Signs of selenium deficiency were evident from diminished biomass in groups fed lower concentrations. Meanwhile selenium toxicity was apparent in the group fed 10 m mol Se/kg. Selenium’s protective effects against MeHg toxicity have been demonstrated in all investigated species, but this is the first study to investigate the effect in insects. This study demonstrates that environmental selenium availability should also be considered when evaluating risks of environmental MeHg exposure.
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