Induction of mouthpart deformities in Chironomus riparius larvae exposed to 4-n-nonylphenol

Chironomid mouthpart deformities have often been associated with sediment c ontamination and are, therefore, currently used to assess sediment quality. Deformities were only occasionally induced in laboratory bioassays. Mouthp art deformities result from a physiological disturbance during larval molti ng. In the past few years it has been shown that some chemicals can exert n egative effects on both vertebrates and invertebrates at the level of endoc rine regulation. As insect molting is hormonally regulated, we wanted to te st the hypothesis that deformities are induced due to a hormonal disruption in the developmental process. The aim of the present study was to test whe ther the endocrine disrupter, Cn-nonylphenol (4NP), induces mouthpart defor mities in chironomids. A laboratory bioassay was performed exposing Chirono mus riparius larvae to 10, 50 and 100 mug l(-1) 4NP. Survival of the larvae was not affected by the tested concentrations, but the frequency of mentum deformities increased significantly (P < 0.01) after exposure to 4NP. (C) 2000 Elsevier Science Ltd. All rights reserved.