Epizootiology of Eustrongylides ignotus in Florida: transmission and development of larvae in intermediate hosts.
Under laboratory conditions, 2 modes of transmission of Eustrongylides ignotus (Nematoda: Dioctophymatoidea) to fish were identified. Eastern mosquitofish (Gambusia holbrooki) became infected after ingestion of either eggs of E. ignotus containing first-stage larvae or aquatic oligochaetes (Limnodrilus hoffmeisteri) containing third-stage larvae of E. ignotus. After removal from the uterus of gravid E. ignotus females and incubation for 17-28 days, depending on temperature, it was found that parasite eggs contained first-stage larvae that were infective to fish and oligochaetes. Larvae developed to the third stage in oligochaetes and were infective to fish 35-77 days postinfection (PI) and when fed to fish, developed to the fourth stage between 127 and 184 days PI. Eggs containing first-stage larvae fed directly to fish developed to the fourth stage between 84 and 105 days PI. The amount of time for development from the undifferentiated egg to the fourth-stage larva was 78-156 days shorter when fish ingested eggs containing first-stage larvae than when fish ingested oligochaetes containing third-stage larvae. Three species of large piscivorous fish, including black crappie (Pomoxis nigromaculatus), largemouth bass (Micropterus salmoides), and warmouth (Lepomis gulosus), were fed mosquitofish containing fourth-stage larvae. At necropsy, live E. ignotus larvae were recovered from all 3 species. Several fish had multiple infections after ingesting > 1 larva, indicating that bioaccumulation of the parasite in the food chain may occur.
Coyner
Donald F
DF
Department of Pathobiology, College of Veterinary Medicine, University of Florida, Gainesville, Florida 32611, USA.
Spalding
Marilyn G
MG
Forrester
Donald J
DJ
D000818:Animals; D003532:Cyprinodontiformes / Q000469:parasitology*; D017159:Dioctophymatoidea / Q000254:growth & development* / Q000502:physiology / Q000648:ultrastructure; D017189:Enoplida Infections / Q000453:epidemiology / Q000469:parasitology / Q000635:transmission / Q000662:veterinary*; D005260:Female; D005393:Fish Diseases / Q000453:epidemiology* / Q000469:parasitology / Q000635:transmission; D005431:Florida / Q000453:epidemiology; D007814:Larva / Q000254:growth & development / Q000648:ultrastructure; D008297:Male; D008855:Microscopy, Electron, Scanning / Q000662:veterinary; D009835:Oligochaeta / Q000469:parasitology*; D010063:Ovum / Q000502:physiology / Q000648:ultrastructure; D010473:Perciformes / Q000469:parasitology*