Lethal Effects of Insecticides on Copepod Cyclops sp.
Brianna Ferrullo-Szakacs
Insecticides are widely used for the control of insects on both crops and yards. After application, these insecticides can end up in waterways via runoff, which can occur due to rain and watering. When these insecticides end up in waterways, they have extremely toxic effects on aquatic organisms, including mortality, changes in behavior, size reduction, difficulty avoiding predators, and a lower tolerance for temperature changes. This experiment aims to investigate some of the toxic effects insecticides can have on aquatic systems. We tested the lethal effects of household insecticides on Cyclops sp., a common freshwater copepod. The copepods were exposed to the insecticides Home Defense, Triazicide, and Amdro Quick Kill containing the active ingredients Bifenthrin, Gamma-Cyhalothrin, and Zeta-Cypermethrin respectively, at concentrations of 0, 1, 5, 10, 25, and 50 parts per billion. All three active ingredients are pyrethroids which are sodium channel modulators. Both Zeta-Cypermethrin and Gamma-Cyhalothrin are type II pyrethroids and Bifentrhin is a type I. Previous studies have found that Type II pyrethroids are lethal at lower concentrations due to them having a greater effect on sodium channels. Therefore, we predicted that Triazicide and Amdro would be more lethal than Home Defense. We calculated the LC50 using the AAT Bioquest LC50 calculator. At high concentrations, complete mortality was seen with all three insecticides, however, Amdro and Triazicide were found to be more toxic than Home Defense. Triazicide was determined to be the most toxic with an LC50 value of 1.06 ppb. Amdro and Home Defense were found to be less toxic with LC50 values of 8.06 ppb and 15.58 ppb respectively. Our findings further highlight the dangers of insecticides because at this relatively low concentrations, valuable organisms are being removed from waterways.
Brianna is a senior biology major with a minor in photography. She is a member of Lander’s Honor College, Gamma Phi Beta sorority and is the current president of Order of Omega honor society. She will graduate in May 2023, after which she will attend graduate school at the University of South Carolina for a masters in secondary education.