Suchart UpathamPairote PrempreeJittinand Tandulyaseri2023-10-202023-10-20198719872023Thesis (M.Sc. (Environmental Biology))--Mahidol University, 1987https://repository.li.mahidol.ac.th/handle/20.500.14594/90590The acute toxicity of dieldrin and carbofuran to common silver barb, Puntius gonionotus (Bleeker) was studied by using 96-h static bioassays method in water of moderate hardness (110-120 mg/l) as CaCO(,3)and temperature 25 -28 degree C. Five experiments were conducted: two for single toxicant (dieldrin and carbofuran) and three for mixtures of dieldrin and carbofuran at the toxicity ratios of 1:1, 2:1 and 1:2. Concentrations of mixtures were expressed in "toxic unit" by taking them as proportion of 96-h LC(,50) values. The results showed that the incipient lethal levels (96-h LC(,50) and the 95% confidence limits were 0.0113 (0.0106-0.0119) mg/l for dieldrin and 1.275 (1.201-1.343) mg/l for carbofuran. The incipient lethal levels (96-h LC(,50)) and the 95% confidence limits of dieldrin to carbofuran at the toxicity ratios of 1:1 and 1:2 were 1.04 (0.98-1.10) and 1.09 (1.02-1.15) toxic units, respectively, which indicated additive joint action. The toxicity ratio of dieldrin to carbofuran at 2:1, the incipient lethal level (96-h LC(,50)) and the 95% confidence limits were 1.44 (1.38-1.50) which exhibited less than additive joint action. Dieldrin was significantly (P < 0.05) 112.389 folds more active than carbofuran, with 95% confidence limits ranging between 102.172 and 123.628. For dieldrin-carbofuran mixtures at 1:1 and 1:2, the relative potency did not differ significantly from dieldrin. For dieldrin-carbofuran mixtures at 2:1, the results showed that dieldrin was significantly 1.44 folds more toxic than dieldrin-carbofuran mixtures (2:1), with 95% confidence limits ranging between 1.309 and 1.584. There were no difference among 96-h LC(,50) values and relative potency values calculated by the methods of Finney (1971) and Litchfield and Wilcoxon (1949).vii, 112 leaves : ill.application/pdfengBiological AssayCarbofuran -- toxicityDieldrin -- toxicityPesticides -- toxicityFishes, Fresh-WaterMahidol University