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Keywords:

  • Small mammals;
  • Feed aversion;
  • Paraquat;
  • Carbofuran;
  • Ecological assessment

Abstract

Behavioral responses to environmental chemicals take various forms that may influence the hazard associated with chemical exposures in the field. From integrated laboratory-field studies that addressed the wildlife hazard associated with two chemicals—paraquat and carbofuran—commonly applied in various agricultural practices, the role of behavioral responses to environmental toxicants may be illustrated. For small mammals, and in particular the cricetid and murid rodents, olfactory and gustatory cues are prominent in influencing the perception of environmental chemicals and eliciting direct or indirect responses to chemical cues. In laboratory studies, subacute dietary exposures were evaluated using microtine rodents; feed aversion and toxicant avoidance appeared the most significant behaviors elicited by feed tainted with either paraquat or carbofuran. Feed aversion was associated with delays in the time-to-first-breeding in carbofuran-exposed females, while a female-biased sex ratio in offspring of paraquat-exposed breeding pairs was not uncommon in these laboratory feeding exposures. Preliminary field investigations that estimated population-level effects (population size and structure), however, suggested that toxicant avoidance, perhaps mediated through responses like feed aversion, may have ameliorated these indirect toxicant effects. While reproductive function and population-level effects in small mammals were not apparent in these preliminary field studies, the laboratory studies suggested that various subtle responses related to altered reproductive function may become apparent in long-term field studies, especially if routes of exposure and chemical bioavailability were altered and different chemical formulations and chemical mixtures were used.