Proterometra macrostoma (Faust) (Trematoda: Azygiidae): Further Studies on Strains at North Elkhorn Creek, Scott County, Kentucky

Abstract

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.