Toxicity of some synthetic pyrethroids to red swamp crayfish (Procambarus clarkii, Girard 1852) and common carp (Cyprinus carpio, L. 1758), in laboratory tests.

The acute toxicity of three synthetic pyrethroids (Cypermethrin, Deltamethrin and Cyfluthrin) to red swamp crayfish (Procambarus clarkii) and the mortality after long-term exposition of young common carps to Deltamethrin were determined in standardized laboratory tests. The aim of this study was to evaluate the possibility of limiting the expansion of crayfish by the use of these compounds and the implications of their use on fish. Red swamp crayfish experienced high sensibility to pyrethroids as expressed by the LC50-24h: 0.14 \ub5g/l for Cypermethrin, 0.17 \ub5g/l for Cyfluthrin and 0.22 \ub5g/l for Deltamethrin. No mortality was observed in common carp during the long term (24 days) exposure test at initial concentration of 22,0 \ub5g/l of Deltamethrin. The concentrations of Deltamethrin in muscle of crayfish and common carp were under the limit of quantification of the gas-chromatographic method in all the tests. The results suggest that synthetic pyrethroids may be suitable to control or to eradicate nuisance populations of red swamp crayfish, in small and limited areas

Fungal infections in allochthonous freshwater crayfish in northern Italy.

A mycological study, involving Aphanomyces astaci, was carried out on allochthonous freshwater crayfish, which are increasing in number in the streams of Northern Italy. A. astaci is the agent of the crayfish plague a disease which has devastated many European native populations of freshwater crayfish. It appears that this disease is endemic to North America and that the higher resistance of the North American species is a result of the coevolution of both the fungus and the host. The North American crayfish carry this fungus as a chronic infection in melanized spots in their cuticle. Small pieces of the exoskeleton of 12 specimens of red swamp crayfish Procambarus clarkii (Girard), coming from the canals of the province of Bologna, and of 2 signal crayfish Pacifastacus leniusculus (Dana), coming from the Auenbachl stream in the province of Bolzano, were placed in plates containing glucose-yeast extract agar with penicillin and oxolinic acid and incubated at room temperature. Fusarium spp. was recovered from a total of 9 crayfish of the above-mentioned species; it was most frequently isolated from brown lesions of the exoskeleton (Burn spot disease). Dictyuchus sp was isolated from cottonwool-like tufts in one P.clarkii. An oomycete with morphological characteristics resembling A. astaci was found in one specimen of red swamp crayfish. The role played by fungi in the pathologies of freshwater crayfish is briefly discussed

Preliminary disease investigations on white-clawed crayfish Austropotamobius pallipes from streams of Northern Italy.

A total of 99 live and 3 dead white-clawed crayfish Austropotamobius pallipes were collected during the summer-autumn 2003 in one creek of Emilia Romagna and four watercourses of Friuli Venezia Giulia in Northern Italy for experimental breeding and health status monitoring. Fifty-one animals coming from Bidente river were maintained in tanks for breeding, reproduction and restocking, while 30 other specimens (27 living and 3 dead) were examined in the laboratory to evaluate their health status. Parasitological surveys were carried out on gills; mycological investigations on exoskeleton, walking legs and cuticle of abdomen; bacteriological examinations of inoculations from the haemolymph and histopathological analysis on full sections of cephalothoraxes and sections of abdomen. In the gill-chambers, the gill filaments and exoskeleton were observed for ectocommensal peritrich protozoans Epystilis sp. and Cothurnia sieboldii. In crayfish sampled in four creeks Branchiobdella italica, B. astaci and B. parasita were isolated. Hyaline and dematiaceous hyphomycetes were frequently observed and Fusarium sp. and Saprolegnia sp. were isolated from cuticular lesions. Mortalities occurred in two tanks, respectively after 2 and 4 weeks, in adult crayfish utilized for breeding, with about 23,5% cumulative mortalities. In both cases the crayfish were weak, anorexic and lethargic. Respectively four and eight moribund samples coming from the two breeding tanks, in which mortalities occurred, were submitted to investigations. In the first case the mortalities were attributed to Thelohania-like organism and in second case the mortalities were associated with enteric bacteria. Bacterial lesions were observed in the dead crayfish found in Chiar\uf2 and Bidente River and heavy damage of the gills in the presence of branchiobdellid cocoons was observed on crayfish dead in Orvenco creek

Evaluation of the toxicity of synthetic pyrethroids to red swamp crayfish (Procambarus clarkii, Girard 1852) and common carp (Cyprinus carpio, L. 1758)

The acute toxicity of three synthetic pyrethroids (Cypermethrin, Deltamethrin and Cyfluthrin) to red swamp crayfish (Procambarus clarkii) and the mortality after long-term exposition of young common carp to Deltamethrin were determined in standardized laboratory tests. The aim of this study was to evaluate the possibility of limiting the expansion of crayfish by the use of these compounds and the implications of their use on fish. Red swamp crayfish experienced high sensitivity to pyrethroids as expressed by the LC50-24h: 0.14 mu g/l for Cypermethrin, 0.17 mu g/l for Cyfluthrin and 0.22 mu g/l for Deltamethrin. No mortality was observed in common carp during the long term (24 days) exposure test at initial concentration of 22.0 mu g/1 of Deltamethrin. The concentrations of Deltamethrin in muscle of crayfish and common carp were under the limit of quantification of the gas-chromatographic method in all the tests. The results suggest that synthetic pyrethroids may be suitable to control or to eradicate nuisance populations of red swamp crayfish, in small and limited areas