Photos from the 2003 East Tennessee Collegiate Division Meeting of the Tennessee Academy of Science held at Pellissippi State Technical Community College
4/11/2003
Catherine Webb, Maryville College
ABSTRACT
The Effects of Malathion on Growth and Development of Xenopus laevis
Amphibian declines have been occurring for decades, and much of this decline is attributed to environmental contaminants. One such chemical is malathion, an organophosphate insecticide that is widely used for the control of mosquitoes and other insects. Developing amphibians are often found in areas where malathion is used, and are thus often exposed to the chemical during metamorphosis. Two-week-old Xenopus laevis tadpoles were divided into four groups: control (water), 1.0 ng/L malathion, 1.0 ug/L malathion, and 1.0 mg/L malathion. During their 36-day exposure to malathion, the highest concentration displayed bent tails, unusual swimming behavior, and a higher mortality rate than the other three groups (p<0.0001). The smaller tadpoles tended to die first, so by the end of the experiment, in the high concentration, only the large tadpoles were alive. Because of this phenomenon, tadpoles in the control group were significantly larger than the low and medium concentrations (p=0.002 for weight and p=0.036 for length), but they were not different from the high concentration. However, control tadpoles were significantly more developed (p=0.004) than all three other groups. Malathion, at 1.0 mg/L, was found to cause bent tails, abnormal swimming behavior, and a high mortality rate in developing tadpoles.
