Effects of Hormone Mimetid Insecticide Tebufenozide on Aquatic Organisms

The effects of the non-steroidal ecdysteroid agonist tebufenozide on larvae of C. faviplumus and C. riparius were tested in the laboratory. In the most treatments it reached a statistically significant difference from the control condition. As the concentration of tebufenozide was increased, a relatively larger proportion of the observed mortality was associated with the metamorphosis and molting process. Also, the larval mortality of the first larvae was higher than the fourth-instar larvae in C. riparius. In terms of development, the effects of tebufenozide were delayed growth stage in relatively lower concentration such as 10 $\mu\textrm{g}$/L treatments. Based on the mortality, the susceptibility followed the first-instar C. riparius > the fourth-instar C. flaviplumus > the fourth-instal C. riparius. The morphological effects showed that the first and second segments of body of exposed larvae with tebufenozide expanded slowly and not made a complete cephalothorax of pupae during long times or days. And the head capsule slipped down and forward, revealing a fragile and non-pigmented, unsclerotized new head capsule. There was obvious significant difference in the male/female ratio in contaminated fourth larvae of C. riparius. Also, due to the different emergence periods of male/female in low insecticide concentrations, mating chances or opportunities of insects should be decreased. Accordingly, ecological strategies for keeping of sustainable populations should be disrupted.