A comparison of the effects of organophosphate insecticide exposure and temperature stress on fluctuating asymmetry and life history traits in Culex quinquefasciatus

Effects of exposure to a non-chemical (temperature) or chemical (organophos phate insecticide) stressor during larval development were compared in Cule x quinquefasciatus mosquitoes. Stress was measured in two ways: using conve ntional life history traits (survival, development time and a measure of bo dy size) and by calculating the degree of developmental instability from th e departure from bilateral symmetry of wing characters (fluctuating asymmet ry). Increasing insecticide dose, but not temperature, was observed to elev ate wing fluctuating asymmetry in male but not female mosquitoes, Insectici de treatment reduced survival and was associated with a significant reducti on in wing trait sizes in both females and males but did not significantly affect development time. Temperature was associated with a significant redu ction in all life history traits in both sexes. Therefore wing fluctuating asymmetry in C quinquefasciatus cannot be used as a general biomonitor of a ll stress, although it may have potential as a more specific monitor of che mical stress. It needs to be complimented with other measures such as life history and biochemical methods. The significant differences in response be tween sexes may impact on results of short-term larval exposures to insecti cides. (C) 2001 Elsevier Science Ltd. All rights reserved.