Premium
The Toxicity of Bayluscide and TFM to Tubifex tubifex : Implications for Chemical Control of the Oligochaete Host of Myxobolus cerebralis , the Causative Agent of Whirling Disease
Author(s) -
Kowalski Dan A.,
Bergersen Eric P.
Publication year - 2003
Publication title -
north american journal of aquaculture
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.432
H-Index - 41
eISSN - 1548-8454
pISSN - 1522-2055
DOI - 10.1577/c02-036
Subject(s) - tubifex tubifex , tubifex , biology , toxicity , oligochaeta (plant) , microcosm , parasite hosting , microbiology and biotechnology , toxicology , veterinary medicine , zoology , ecology , chemistry , medicine , organic chemistry , world wide web , computer science
Standard 24‐h toxicity tests were performed to determine the acute toxicity of Bayluscide (5,2′‐dichloro‐4′‐nitrosalicylanilide) and 3‐trifluoromethyl‐4‐nitrophenol (TFM) to two strains of the oligochaete worm Tubifex tubifex exposed and unexposed to Myxobolus cerebralis , the causative agent of whirling disease. In addition, microcosm trials were conducted to test the effect of three treatment levels of each chemical on the density of T. tubifex in an earthen hatchery pond. In the toxicity tests, worms that were susceptible to M. cerebralis infection were more sensitive to both chemicals than worms that were resistant to the parasite. The toxicity differences of exposed and unexposed worms within a lineage were not as great as those between lineages. Among worms that were susceptible to M. cerebralis , the concentrations of TFM that were lethal to 50% of the test organisms (LC50s) were 6.3 mg/L for worms that had been exposed to M. cerebralis myxospores and 7.3 mg/L for unexposed worms; for resistant worms, the corresponding LC50s were 8.2 and 7.7 mg/L. Among susceptible worms, the LC50s of Bayluscide were 0.060 mg/L for organisms exposed to M. cerebralis myxospores and 0.062 mg/L for unexposed organisms; resistant worms had LC50s of 0.096 and 0.106 mg/L. In the microcosm trials, Bayluscide treatments reduced worm densities by 73–82%, while the TFM treatments reduced worm densities by 34–88%. Given its rapid degradation, relatively selective toxicity, lower cost, and regulatory status, Bayluscide appears to be the best candidate for further study as a chemical control of the oligochaete host of the parasite that causes whirling disease in salmonid fishes.