Genetic Resistance to DDT in the Japanese Quail Coturnix Coturnix Japonica ,

Abstract

Selection studies of resistance to DDT included eight generations of quail consisting of two selected lines and one control line. One selected line differed from the other in that, in addition to mass selection, birds were chosen on the basis of family merit. Selected lines were fed a diet containing 200 p.p.m. DDT during the first 30 days of life. In order to test for resistance, part of the control lines were also given DDT diets, and the mortality of the control was compared to the mortality of the selected lines.Development of resistance started to appear after the third generation of selection. This was evidenced by the lower mortality among the selected lines than in the control line fed DDT. If the selected lines had stored DDT in the body, cold exposure or partial starvation (release of energy from the fat) would presumably increase the DDT levels in the blood and other sensitive tissue, causing mortality due to DDT toxicity. This was put to test by exposing DDT-fed resistant lines and the DDT-fed control group to partial starvation and cooler temperatures. Under these conditions, the selected lines were lower in mortality than the control.Among the resistant lines, the females were less resistant than males. These lines showed some cross-resistance to another hydrochlorinated pesticide lindane.A conclusion drawn from this study is that it is possible to develop a strain of quail resistant to DDT out of the less resistant population by selection.