Meeting Abstract

70.5  Friday, Jan. 6  Significance of snails as habitat patches for their concomitant parasites in novel environments. TOLLEY-JORDAN, L. R.*; CHADWICK, M. A.; Jacksonville State University; Kings College London ljordan@jsu.edu

Melanoides tuberculata and Thiara granifera (Caenogastropoda: Thiaridae), snails native to Asia, were introduced to the Comal springs, Texas, USA in the 1960s. Subsequently, the introduction of invasive, trematode parasites, Centrocestus formosanus and Haplorchis pumilio (Heterophyidae) infected M. tuberculata and Philophthalmus gralli (Philophthalmidae) infected both snail species. We determined 1) infection rates among parasites within a snail population and 2) if host selection of M. tuberculata or T. granifera was related to snail abundance and snail size. Snails were sampled from October 2001 to April 2002 from a range of habitats. Snail lengths (mm) and parasites found in snail tissues were recorded. Differences in infection rates between host species and among parasites within each host population were tested by comparing 95% confidence intervals estimated by bootstrapping numbers and lengths of collected snails. In total, 841 M. tuberculata ranging from 6-56 mm and 1,978 T. granifera ranging from 1-31mm were collected. Infection rates in both snail populations ranged from 0.1 -2.0%. No snails smaller than 20 mm (70% of M. tuberculata and 95% of T. granifera) were found infected. No significant differences in P. gralli infection between M. tuberculata and T. granifera occurred. In M. tuberculata, C. formosanus was the dominant parasite. Thus, as larger snails occurred infrequently in the springs, available patch size for parasites was reduced. The limited availability of suitable snail hosts may have led to the dominance of C. formosanus infecting M. tuberculata and low levels of infection of P. gralli in both snail species.