Detection of Apoptosis in Early Life Stages as a Tool to Evaluate Chemical Control of Invasive Species
ENGINEER RESEARCH AND DEVELOPMENT CENTER VICKSBURG MS
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Traditionally, the efficacy of chemical control strategies for aquatic nuisance species ANS has been assessed using indices of acute mortality. However, such lethality endpoints may be overly conservative estimates of control. Lower doses of chemicals may significantly compromise organisms at the cellular level and eventually lead to mortality or suspension ion of development. These effects are likely to occur prior to any observable mortality. The use of cell integrity assays may help to further optimize control strategies for ANS by assessing chemical sensitivity at substantially lower concentrations than traditional acute toxicity studies revealed in a companion technical note, Application of life stage sensitivity data in chemical control strategies for invasive animal species Millward et al. 2007. This technical note focuses on one particularly sensitive assay that may provide an alternate measure of efficacy to acute lethality. While it is intuitive that chemical control strategies designed for the more sensitive life stages might require lower treatment doses, absolute mortality may not be required for effective population control of a target species. Many benefits, including lowered cost, reduced risk for nontarget species, and increased effectiveness of control strategies could be realized by understanding how lethality is induced. In addition, detecting sublethal concentrations that may impact or inhibit reproduction, recruitment to the population, and the continuation of the life cycle could further enhance our understanding of control efficacy. For these studies, sensitivity at different life stages was assayed by a suite of cell bioassays that convey information regarding the health and vitality of individual cells in embryos and larval stages and the developmental competence of early life stages.