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Researchers in Norway studied the effects of the antiparasitic drug teflubenzuron on European lobster and found that the Cumulative mortality was higher in all medicated groups compared with the control group. (Ole B. Samuelsena, Bjørn T. Lunestadb, Eva Farestveita, Ellen S. Grefsruda, Rita Hannisdalb, Bjarte Holmelidb, Tore Tjensvollb, Ann-Lisbeth Agnalta)

After moulting, says the researchers, a considerable number of the medicated lobsters were observed with deformities in various organs. The half-life of teflubenzuron in lobster was estimated to 3.4 days.

This study describes experiments carried out to examine effects of teflubenzuron, used in delousing farmed salmon, on a non-target species, the European lobster (Homarus gammarus). Juvenile lobsters were fed two doses of teflubenzuron, 10 and 20 mg/kg successively for 7 days corresponding to a standard medication of the fish (10 mg/kg day) and twice the standard dose (20 mg/kg day).

Monitoring lasted 3 months to include at least one moulting period for all individuals. Cumulative mortality was higher in all replicates given medicated feed compared with the control group. Drug residue was analysed in all juveniles that died, in addition to 12 juveniles at day 8 and the first 12 surviving lobsters.

At the end of the study a considerable number of juvenile lobsters were observed with deformities in various organs; carapace, walking legs, cheliped, tail fan, abdomen and antenna. The occurrence of observed deformities will most likely affect ability to locate and consume food (antenna, claw and walking legs), respiration (carapace) and ability to move/swim (walking legs, tail fan and abdomen). In total, the mortality and senescent damages were close to 50% in all replicates.