ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 23,76-88 (1992) Toxicity of Lindane to Freshwater Insect Larvae in Compartments of an Experimental Fond S. J. MOUND,* A. PEITHER,~ E. J. TAYLOR,* I. J~TTNER,~ R. BEYERLE-PFNUR,? J. P. LAY,~ AND D. PASCOE* *School of Pure and Applied Biology, University of Wales Cohege of Cardtg P.O. Box 915, Cardtx United Kingdom; and tGSF-Forschungszentrum fir Umwelt und Gesundheit Miinchen, Institut Jiir iikologische Chemie und Bodenokologie, O-8042 Neuherberg, Germany Received March 22, 1991 The acute and chronic toxicities of lindane to larvae of the freshwater insects Chironomus riparius Meigen, Chaoborusflavicans (Meigen), and Sigara striata (L.) were investigated in me- socosm compartments of an experimental pond. The following median lethal concentrations (L&s) were determined: 240~hr LC, of 2.0 pg lindane liter-’ for second instar C. riparius, 72-hr LC5,, of 6.5 gg lindane liter-’ for fourth instar C. riparius, and 96-hr L&s of 4.0 and 3.9 pg lindane liter-’ for fourth instar C. flavicans and fourth or fifth instar S. striata, respectively. Lindane significantly reduced the growth over 10 days of second instar C. riparius compared to that of the control at the treatment concentrations where larvae survived (1.0, 2.5, and 7.0 pg lindane liter-‘). A significant increase in the median emergence time in comparison to that of the control was observed for C. riparius exposed to 0.8 and 2.0 pg lindane liter-‘, with higher con- centrations causing 100% mortality. The findings compare well with previously reported laboratory data on the toxicity of lindane to insects and support the methodology and results of a laboratory growth test for C. riparius. 0 1992 Academic press, Inc. INTRODUCTION Water quality standards for chemicals in freshwater ecosystems are predominantly based on toxicity data from laboratory studies. However, the applicability of these standards to the wide range of physicochemical conditions that prevail in natural aquatic ecosystems has been questioned (Lee and Jones, 1983). It is also known that disparities in such parameters affect laboratory bioassay results (Lee, 1973; Stephenson, 1983; Pascoe and Edwards, 1989). Therefore field investigations are required to validate the methodologies and end points of laboratory bioassays and to verify environmentally acceptable toxicant concentrations. Aquatic mesocosms are suitable for such studies because they incorporate the natural variability of field conditions while allowing some of the experimental manipulation that is possible in the laboratory. Experimental pond mesocosms have been used previously in ecotoxicological studies to determine the effects of various toxicants, including 2,4-D DMA (Boyle, 1980), cypermethrin (Crossland, 1982), synthetic oil (Sayler et al., 1983), coal-derived oil (Giddings et al., 1984; Giddings and France, 1985), atrazine (deNoyelles and Kettle, 1985; Larsen et al., 1986), fluorene (Boyle et al., 1985), 3,sdichloroaniline (Crossland and Hillaby, 1985), pentachlorophenol (Crossland and Wolff, 1985), methyl parathion (Crossland, 1984), 2,4-dichlorophenoxyacetic acid (Stephenson and Mackie, 1986), and cadmium (Sherman et al., 1987). It has been suggested (Lay et al., 1984a) that using separate ponds for each toxicant concentration, even within one experimental plot, may result in considerable biological 0147-6513/92 $3.00 Cop&Id 0 1992 by Academic F?ess, Inc. AU rights of reproduction in any form reserved. 76