Accumulation and effects of methyl mercury hydroxide in a terrestrial food chain under laboratory conditions

Abstract

Seedlings of tomato ( Lycopersicon esculentum Mill.), corn ( Zea mays L.) and bean ( Phaseolus vulgaris L.) were grown in complete nutrient solutions containing methyl mercury hydroxide (MMH). Aphids ( Macrosiphum gei Ashmead) and green lacewing larvae ( Chysopa carnea Stephens) were reared on the plants. Experiments were designed to examine the rate of accumulation and sensitivity to MMH. Tomatoes were killed within four to eight days at concentrations of MMH exceeding 0·05 ppm. Growth was inhibited by concentrations of 0·01 ppm for tomatoes and 0·05 ppm for corn and beans. Maximum mercury concentrations were found on the second day of treatment in tomato foliage, on the fourth day in aphids and on the sixth day in lacewings. Tomatoes, grown in 0·006 ppm MMH solutions for two days, concentrated mercury in foliage to 250 times while aphids and lacewings concentrated mercury to 1670 and 4178 times the concentration in treatment solutions, respectively. Significant decrease in fecundity and increase in development time occurred when aphids fed on tomatoes growing in 0·02 ppm MMH.