Acute toxicity test of agricultural pesticides on silver catfish (Rhamdia quelen) fingerlings

Abstract

Toxicity risks of agricultural pesticides to fishes are pivotal. Currently, many questions remain unsolved regarding to the toxicity of commonly used pesticides to silver catfish (Rhamdia quelen), a South American catfish. The present studies have been designed to investigate the acute toxicity and the lethal concentration (LC50) of four herbicides, two fungicides and two insecticides to silver catfish fingerlings. All experiments were carried out in triplicates, in a static bioassay system, using commercially available pesticides. The data was analyzed through the Trimmed Spearman-Karber method available from the Environmental Protection Agency. The 96hLC50 and 95% lower and upper confidence limits, respectively, for the following pesticides were determined: glyphosate (7.3mg L-1; 6.5-8.3), atrazine (10.2mg L-1; 9.1-11.5), atrazine+simazine (10.5mg L-1; 8.9-12.4), mesotrione (532.0mg L-1; 476.5-594), tebuconazole (5.3mg L-1; 4.9-5.7), methylparathion (4.8mg L-1; 4.3-5.3), strobulurin and triazol (9.9mg L-1; 8.7-11.2). Diflubenzuron was also tested and caused no fish mortality up to 1g L-1. The toxic concentration of these pesticides to silver catfish fingerlings fell above the concentration used for application in the field and, except following accidental application or misplacing of empty recipients, it should not cause fish mortality. Nonetheless, the data obtained will be useful to study the long-term effect of these products on the hematological, biochemical, hormonal and immunological parameters of silver catfish and related fish species in South Brazil.

Toxicidade aguda de herbicidas a tilápia (Oreochromis niloticus)

“…Para Oulmi et al (1995), a exposição da espécie de truta Oncorhynchus mykiss ao atrazina resultou em 50% de mortalidade em concentração próxima a 10 mg L -1 ; contudo, no teste com embriões desse mesmo peixe esse valor diminuiu para 1 mg L -1 . Para Prassad & Reddy (1994) (Kreutz et al, 2008). Avaliando a variação de peso observada entre o início da incubação dos alevinos e 120 horas de exposição, observa-se diminuição acentuada de massa corporal em função da presença do herbicida.…”

New hosts and distribution records of Braga patagonica, a parasite cymothoidae of fishes from the Amazon

“…In Brazil, this product has also been used to control other crustacean ectoparasites, because it has low toxicity to fish (Kreutz et al, 2008, Tavares-Dias et al, 2011. In order to be suitable for fish farming, a chemical product must be safe for fish, highly efficient and rapidly degraded, not interfering with the water, easily applicable and low cost.…”

Perulernaea gamitanae (Copepoda: Lernaeidae) parasitizing tambaqui (Colossoma macropomum) (Characidae) and the hybrids tambacu and tambatinga, cultured in northern Brazil

“…Studies with juvenile rainbow trout Oncorhynchus mykiss and coho salmon Oncorhynchus kisutch (McKague and Pridmore, 1978), also Rhamdia quelen (Kreutz et al, 2008) and Zungaro zungaro (Pelli et al, 2008), have examined the toxicity of Diflubenzuron and they suggest that its mean lethal concentration for 96h exposure (LC 50 -96h) is greater than 150mg.L -1 . However, the concentration of Diflubenzuron recommended for direct application in ponds is 100 to 200g/1000m 3 of water, which corresponds to 0.1-0.2mg.L -1 (Martins, 2004).…”

“…However, the concentration of Diflubenzuron recommended for direct application in ponds is 100 to 200g/1000m 3 of water, which corresponds to 0.1-0.2mg.L -1 (Martins, 2004). Hence, this product has low toxicity to fish (Burtle and Morrison, 1987;Moraes and Martins, 2004;Kreutz et al, 2008;Pelli et al, 2008;Schalch et al, 2009). Besides being effective in the treatment against crustacean parasites (Burtle and Morrison, 1987;Routh et al, 1993;Moraes and Martins, 2004;Schalch et al, 2009), Diflubenzuron is degraded in aerobic conditions (Routh et al, 1993;Pelli et al, 2008).…”