-The objective of this work was to evaluate the efficacy of eugenol as an anesthetic for juvenile common snook, and to determine the minimum effective concentration for use in handling procedures. In the first trial, juvenile common snook were subjected to immersion baths at 25, 50, 75, 100, 125, and 150 mg L -1 eugenol concentrations, after which induction and recovery times were evaluated. In the second experiment, the lethal exposure time (LT 50 ) at 75 mg L -1 was estimated. Minimum effective eugenol concentration was 50 mg L -1 , and the stage of deep anesthesia and recovery were, respectively, reached at 126.3 and 208.8 s. At 75 mg L -1 , LT 50 was 1,314 s, and induction time and recovery were also satisfactory; however, fish cannot tolerate over 229 s exposure.Index terms: Centropomus undecimalis, anesthesia, fish farming, fish handling. Eugenol como anestésico para juvenis de robalo-flechaResumo -O objetivo deste trabalho foi avaliar a eficácia do eugenol como anestésico para juvenis de robalo-flecha e determinar a concentração mínima eficaz que pode ser utilizada em procedimentos de manejo. Termos para indexação: Centropomus undecimalis, anestesia, piscicultura, manejo de peixes.
The efficiency of double thermal shock to induce tetraploidy in Rhamdia quelen (jundiá) at different post-fertilization periods was assessed. Each test was performed with 20 mL of eggs (10, 15, 20, 25, 30 and 35 mpf -minutes post-fertilization) exposed to hot thermal shock (39±0.2ºC) for 3 min, followed by cold thermal shock (1.0±0.1ºC) for 30 min. A control group was also employed. Fertilization and hatching rates were evaluated 12 and 30 hours post-fertilization (hpf), respectively. After 60 hpf, twenty-five larvae from each experimental unit were fixed to verify the ploidy by flow cytometry. Control fertilization rate was 87.83% and reached 23. 4%, 28.5%, 30.4%, 20.0%, 30.3%, 36.7% respectively for 10, 15, 20, 25, 30, 35 mpf. Tetraploids were detected only at 15 mpf and 20 mpf. This is the first research of tetraploidy in jundiá obtained by hot and cold shocks, making possible the improvement of this technique.Key words: jundiá; tetraploidy; thermal shock; poliploidy.. RESUMOAvaliou-se a eficiência do choque térmico duplo para induzir tetraploidia em jundiá Rhamdia quelen em diferentes tempos pós-fertilização. Vinte mililitros de ovos (10, 15, 20, 25, 30 e 35 mpf -minutos pós-fertilização) foram tratados com choque térmico quente (39±0,2ºC) durante 3 min seguido de choque térmico frio (1,0±0,1ºC) durante 30 min. Um grupo controle foi utilizado. As taxas de fertilização e de eclosão foram medidas 12 hpf (horas pós-fertilização) e 30 hpf, respectivamente. Decorridas 60 hpf, 25 larvas de cada unidade experimental foram fixadas para verificação da ploidia, por citometria de fluxo. A taxas de fertilização foram de 87,83% para o controle e de 23,4%; 28,5%; 30,4%; 20,0%; 30,3% e 36,7%, para os grupos tratados com choque térmico aos 10, 15, 20, 25, 30, 35 mpf, respectivamente. Encontraram-se tetraploides apenas nos grupos de ovos tratados aos 15 mpf e 20 mpf. Este é o primeiro trabalho de indução de tetraploidia em jundiá por choques térmicos quente e frio, o qual possibilitou o aperfeiçoamento dessa técnica.Palavras-chave: jundiá; tetraploide; choque de temperatura; poliploidia.
ABSTRACT. The objective of this study was to determine the LC 50 (96h) of two pesticides: Sirius ® 250 SC herbicide of the pyrazosulfuron-ethyl group, and Talcord ® insecticide of the permethrin group, on juvenile Litopenaeus vannamei. Shrimp total hemocyte count (THC) was also determined as an indication of physiological alterations caused by the pesticides. Juvenile shrimp (5.0 ± 0.5 g) were exposed to the following concentrations: 0, 0.1, 1.0, 10, 100 and 1000 μg L . There were no significant changes in the THC between control and test groups. No Sirius ® 250 SC concentrations tested killed more than 50% of the shrimp; therefore, the herbicide was considered not toxic to the juveniles. However, the THC showed significant differences between the control and test groups, suggesting sublethal effects to L. vannamei juveniles. According to the results, the insecticide Talcord . Não houve alterações significativas da CTH entre as médias dos grupos-controle e dos submetidos ao inseticida. Com base nas concentrações testadas do herbicida Sirius ® 250 SC, não foi possível determinar a CL 50 (96h), assim, este produto não foi considerado tóxico para os juvenis de L. vannamei. Porém, a CTH dos camarões expostos ao herbicida demonstrou diferenças significativas entre as médias do controle e dos tratamentos, o que evidenciou efeito subletal. Os resultados permitem concluir que o inseticida Talcord ® é altamente letal para os juvenis de L. vannamei e o herbicida Sirius ® 250 SC, apesar de não ter a mesma toxicidade, apresenta efeito subletal relacionado com a diminuição na CTH. Os resultados sugerem a existência de riscos em se cultivar L. vannamei nas proximidades de fazendas de arroz, em que defensivos agrícolas são usados rotineiramente.Palavras-chave: toxicologia, pesticidas, carcinicultura, Litopenaeus vannamei.
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