SOME EFFECTS OF DDT ON THE GUPPY AND THE BROWN TROUT 



By 



Susan Frances King-' 



1/ 



Since the discovery of DDT's insecticidal 

 properties in 1942, pesticide production has 

 mushroomed to over two hundred basic types 

 prepared in more than six thousand formulations. 

 These pesticides have been used extensively in 

 the control of plant and animal pests and disease 

 carriers . The chemical agents used to control 

 insects are, however, deleterious to higher 

 forms of life as well. As a result, precaution- 

 ary measures of pesticide application have 

 evolved along with the development of the pesti - 

 cides. Nonetheless, after application of the 

 chemicals reports of destruction of fish and 

 wildlife are frequently received by the conser- 

 vation offices . 



DDT production constitutes at least 31 

 percent of total pesticide production (Annon., 

 1960). Its uses at present outnumber the uses 

 of the other chlorinated hydrocarbons and it 

 has proven most valuable as a means of con- 

 trolling forest pests. DDT was one of the first 

 insecticides to be studied by conservationists 

 in relation to the effects on fish and wildlife . 

 Evidence of the toxicity of DDT, especially to 

 fishes, determined by field studies and laDora- 

 tory bioassays, has accumulated in the literature 

 It has been ranked fifth in toxicity to fish in a 

 series of nine of the most commonly used 

 chlorinated hydrocarbons (Henderson et al . , 

 1959a). Endrin, toxaphene, dieldrin, and aldrin 

 outrank it in toxicity and heptachlor, chlordane, 

 methoxychlor, and lindane are somewhat less 

 toxic. Much of the early data toxicity, espe- 

 cially that concerning fish, is incomplete and of 

 little practical application, since vital inform- 

 ation such as environmental conditions is often 

 lacking (Cottam et al . , 1946; Nelson et al.,1947; 

 Adams et al. ,1949; Ginsberg et^aL, 1954). More 

 extensive studies of effects of insecticides in 

 the field may be found in the works of Surber 

 (1951), Ingram and Tarzwell (1954), Kerswill and 

 Elson(1955), Shepard(1956, etal., 1959), Leffler 



(1958), Tarzwell (1958), and Keenleyside (1959). 



Some of the first laboratory bioassays 

 on fish were conducted by Surber (1947), Linduska 

 and Surber (1948), and Lawrence (1950). Surber 

 and Lawrence found a vast difference in toxicity 

 levels of insecticides in the laboratory and in the 

 field. The toxicity of DDT to bluegills in the 

 laboratory was .14 ppm (parts per million) and 

 .04 ppm in the field. Even the tolerance level 

 median (TL/m) reported in the literature by 

 different workers for the same species of fish 

 is found to vary considerably. Surber designated 

 .14 ppm and Henderson e^al_. (1959a) .021 ppm 

 DDT as toxic concentrations to bluegills. 

 Henderson has conducted brief bioassays follow- 

 ing standardized procedure on fatheads, bluegills, 

 goldfish, and guppies with ten different chlorin- 

 ated hydrocarbons, including DDT in hard and 

 soft water and in various formulations. Each 

 species varied considerably in sensitivity to 

 each compound. The TL/m in ppm DDT in 

 acetone solution for 96 hours for guppies was 

 .043; for fathead minnows, .032; goldfish, .027; 

 and bluegill, .016. Tarzwell and Henderson 

 (1957) have studied effects of dieldrin, a chlorin- 

 ated hydrocarbon similar to DDT in chemical 

 structure and toxicity effects, on fatheads, small 

 bluegill, and green sunfish . 



Until recently, little consideration was 

 given to the more extensive effects which DDT 

 might have on growth and reproduction of large 

 organisms. Allison (Fishery Research Biologist 

 stationed at the National Fish Hatchery, Jackson, 

 Wyoming) is beginning long term exposure of cut- 

 throat trout to DDT in bath form and in the diet, 

 to study growth and reproduction. In addition, 

 studies to understand effects of size, sex, physical 

 conditions, dosage rate, water chemistry, and 

 environment on toxicity are in progress at the 

 Denver, Colorado, Fish -Pesticide Research 

 Laboratory (De Witt ^al_., 1960). Studies of effects 



1/ Present address: Duke University, Durham, N.C. 



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