Froterometra macrostoma Fishes — Rosen et al. 105 



Figure 5. Histopathology of bliiegill experimentally infected with Froterometra macrostoma: (A) worm oral sucker 

 constricting host tissue, 100 X; H & E (B) hemorrhaging and associated epithelial necrosis in constricted host tissue, 

 400X; H & E (C) detached host tissue in oral sucker of worm, 40X; Hematoxylin & Mallory's Trichrome (D) necrosis 

 of detached host tissue, 400 X; Hematoxylin & Malloiy's Trichrome; e = epithelial necrosis, h = hemorrhage with 

 erythrocytes, 1 = stomach lumen, m = host mucosa, nt = necrotic host tissue, o = oral sucker, s = host submucosa, 

 t = testes, V = ventral sucker. 



December in Kentucky. Thus it appears that 

 P. macrostoma cercariae are available for in- 

 fection of centrarchid fish at North Elkhorn 

 Creek only from spring to early fall. The 

 markedly high prevalence of Type I relative 

 to Type II and III worms from naturally in- 

 fected centrarchids during June and July in 

 our study was likely correlated with increased 

 maturation and shedding of cercariae during 

 these months. Naturally infected fishes ex- 

 amined during the late fall to winter interval 

 would likely possess only Type III or no 

 worms because of (1) lack of cercarial avail- 

 ability due to water temperature and (2) loss 

 of adults after 16 weeks (Riley 1992). A fu- 

 ture, mid-winter collection of centrarchids 

 would be required to verify this. 



Procurement of nutrients by enteric, adult 

 P. macrostoma is apparently accomplished by 

 facilitated diffusion of sugars (Lewis and Ug- 

 lem 1989) coupled with active ingestion of 



host tissues. With regard to the latter, histo- 

 pathology in bluegill seemed limited to the 

 area of worm attachment to the host mucosa. 

 Apparently, these worms feed, detach, and 

 move to other sites, leaving small but visible 

 red lesions with associated hemorrhaging and 

 epithelial necrosis. Overall damage was mi- 

 nor, and fish survival in both experimental and 

 natural infections was unaffected. 



ACKNOWLEDGEMENTS 



This study was supported by a grant from 

 the Undergraduate Research and Creative Pro- 

 jects Program (URCPP) at Berea College to 

 Ronald Rosen. We acknowledge the late 

 Gary. L. Uglem, who provided the first author 

 much insight and support with the P. macro- 

 stoma system. We thank Dr. Bernard Fried, 

 Department of Biology, Lafayette College, 

 and Dr. Allen Shostak, Department of Biolog- 



