Toxicity of fenvalerate to caddisfly larvae: chronic effects of 1- vs 10-h pulse-exposure with constant doses.
Episodic pollution events such as runoff or spraydrift can lead to a short-term (few hours) contamination of aquatic ecosystems with pesticides. So far, different short-term exposures with respect to long-term effects have not been studied. In the present study, caddisfly larvae, typical for agricultural streams (Limnephilus lunatus Curtis, 2nd and 3rd instar) were exposed for 1- vs 10-h to three different equivalent doses (microg h) of fenvalerate. After transfer into an artificial stream microcosm with pesticide-free water, chronic effects were observed over 240 days. Comparison of 1- and 10-h exposure revealed that 1-h contamination leads to stronger effects. The differences were significant for the sublethal endpoints emergence pattern and dry weight of adults (ANOVA, Fisher's PLSD; P < 0.05). In terms of exposure dose, the difference between 1- and 10-h exposure equals a factor of 6 as a mean of all endpoints studied. The following significant effect levels for the 1-h exposure were obtained for the different endpoints investigated: reduced emergence success and production at 0.1 microg l(-1), temporal pattern of emergence at 0.001 microg l(-1), dry weight of adults at 0.01 microg l(-1).
Schulz
R
R
Zoological Institute, Technical University, Braunschweig, Germany. R.Schulz@tu-bs.de
Liess
M
M
D000818:Animals; D007313:Insecta / Q000187:drug effects* / Q000254:growth & development; D007306:Insecticides / Q000633:toxicity*; D007814:Larva / Q000187:drug effects*; D009570:Nitriles; D011722:Pyrethrins / Q000008:administration & dosage / Q000633:toxicity*; D013997:Time Factors; D014131:Trace Elements / Q000032:analysis; D014867:Water / Q000032:analysis; D014873:Water Pollutants / Q000633:toxicity*
D007306:Insecticides; D009570:Nitriles; D011722:Pyrethrins; D014131:Trace Elements; D014873:Water Pollutants; D014867:Water; C017690:fenvalerate