Aquatic insects are used extensively to evaluate water quality. Despite their
widespread use as indicator organisms, relatively little is known about the
organismal characteristics that determine sensitivity differences to individual and
multiple stressors. Insects have evolved several respiratory strategies that range
from breathing atmospheric air to utilizing dissolved oxygen in water via exchange
epithelial surfaces. This dissertation examines the role of respiratory attributes in
determining differential accumulation of the insecticide chlorpyrifos, and further
examines how accumulation rates are affected by temperature shifts. In addition,
the relative roles of uptake rates and target site sensitivity differences are examined
among developmental stages of the aquatic midge, C. riparius. Major findings:
Smaller, gill-bearing insects accumulate chiorpyrifos and water at higher rates
than larger, air-breathing insects.
. Chiorpyrifos and water accumulation rates are highly covariant in aquatic
insects.
Temperature increases affect chiorpyrifos accumulation rates in dissolved
oxygen breathers more so than in air-breathers.
. Earlier instars of C. riparius are more sensitive to chiorpyrifos than later
instars.
Sensitivity differences among 2nd4th instar C. riparius are largely due to
differences in chiorpyrifos accumulation rates
