Hatching of Echinostoma trivolvis miracidia in response to snail host and non-host chemical cues.

Environmental cues are used by many organisms to time life history transitions and can be important for trematode host location. However, while much is understood about how larval trematodes locate hosts, much less is known about the potential role of host cues in the timing of trematode egg development and hatching. We addressed the potential role of host chemical cues in mediating hatching of Echinostoma trivolvis miracidia by comparing hatching in response to cues from the first intermediate host (the snail Planorbella trivolvis), a non-host snail (the snail Goniobasis proxima), and a non-host invertebrate (earthworm, Lumbricus terrestris).

Tadpole size, cholinesterase activity, and swim speed in four frog species after exposure to sub-lethal concentrations of chlorpyrifos.

While physiological biomarkers exist to verify exposure of amphibians in natural populations to agricultural chemicals, the ecological relevance of changes in these parameters is often difficult to determine. We compare the relationship between tadpole cholinesterase (ChE; a common enzymatic biomarker of exposure to OP pesticides) and measures of size and swim speed in four native North American species of anurans (Hyla chrysoscelis, Rana sphenocephala, Acris crepitans, and Gastrophryne olivacea). We used four environmentally realistic levels (1, 10, 100 and 200microg/l) of a commonly used organophosphate pesticide (OP), chlorpyrifos, and examined tadpole response at the conclusion of 4 days of exposure.

Cholinesterase activity and behavior in chlorpyrifos-exposed Rana sphenocephala tadpoles.

Recent studies have found a correlation between organophosphate (OP) pesticide exposure and declines in amphibian populations. We evaluated the hypothesis that this relationship is driven by behavioral changes in developing larvae. Specifically, we examined how exposure to a common OP pesticide, chlorpyrifos, influenced cholinesterase (ChE) activity, mass, and swim speed in Rana sphenocephala tadpoles.