Induction of morphological deformities and moulting alterations in Litopenaeus vannamei (Boone) juveniles exposed to the triazole-derivative fungicide tilt

A tropical marine bioassay was developed with juveniles of Pacific white shrimp, Litopenaeus vannamei, in order to test the acute and sublethal toxicity of Tilt, which is the commercial formulation of the fungicide propiconazole. A 10-d acute toxicity and a 32-d sublethal test were performed. A median lethal concentration (LC50) was determined for different exposure times, resulting in a 24-h LC50 of 1167 (1101-1386) mu g/L (concentration based on active ingredient propiconazole), and reaching a threshold LC50 (72-h) at 1043 (1018-1068) mu g/L. The sublethal exposure test was performed with propiconazole concentrations ranging from 367 to 825 mu g/L. Animals in most treatments showed a significant increase in intermoult duration compared to those in the control treatment, although this did not seem to be concentration-dependent. However, the shrimps exposed to the sublethal concentrations of this fungicide showed morphological deformities, with a significant positive relationship between concentration and deformities of the rostrum, paraeopods, and uropods. Altogether, the results presented indicate the potential effects of Tilt on shrimp, particularly under long-term exposures, although these were found to occur at concentrations exceeding those reported in natural environments.