The objectives of the present study were (1) to compare the frequency of Proterometra macrostoma (Faust) strains and the number of single vs. multiple strain infections in snails, Elimia semicarinata, collected from North Elkhorn Creek during June 2000, 2004, and 2007, (2) to measure selected cercarial strain egg loads and swimming distance under red and white light, and (3) to determine the developmental rate (based on egg stages) of strain I and III adult worms in the bluegill, Lepomis macrochirus. The frequencies of strains I (11.1–28.6%) and III (21.3–35.7%) were the highest, while strains II (4.2–8.8%) and VI (0–1.4%) have been relatively uncommon at North Elkhorn Creek over the last seven years. The majority (76.2–94.3%) of infected snails had multiple strain infections. No significant difference was found between the average egg number (strains I, II, III, IV, V, VII, and VIII) or mean swimming distance (strains I, III, and VIII) of cercariae under red or white light. Similarly, no significant difference was found between the average number of stage I, II, and III eggs, respectively, found in strain I and III adult worms on days 12 and 20 postinfection in experimentally infected bluegill.

The objectives of this study were to describe the (1) location of Proterometra macrostoma rediae in the snail intermediate host, Elimia semicarinata, and (2) daily emergence of cercariae from individual snails over 3 weeks. Decalcification and histological sections of infected snails revealed rediae restricted to the bottom whorl within the mantle cavity in close association with the host gills. A continuous, low-level emergence of cercariae (0.25–0.833 larvae/snail/day) was observed over 21 days. Both moderately frequent (7–12 days) and infrequent (2–6 days) shedding of cercariae were observed (i.e., mean ± SE = 7.3 ± 0.4 days; range = 2–12 days), but no consistent pattern was apparent. The average ± SE number of rediae was significantly smaller in snails shedding only 2–6 days (11.9 ± 2.9) than snails shedding between 7–12 days (35.2 ± 8.5) at the termination of the experiment.

The objectives of this study were to describe the effect of light wavelength and osmolality on the vertical swimming distance of the cercaria of Proterometra macrostoma. Significant differences were found in the average swimming distances and electrical burst activity in the tail of cercariae exposed to red vs. blue, green or white light, but no difference was observed when the last three colors were compared to one another with one exception. Cercarial swimming decreased slightly after 12 hr PE (post-exposure) in artificial pond water (15 mOsm) and artificial snail water (102 mOsm). By contrast, a significant reduction in swimming distance was observed in distilled water (0 mOsm) and artificial snail water with two different concentrations of mannitol (180 and 267 mOsm).