. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 430 PERRY, MATTSON AND BUCKNER tervals before treatment with DDT. The reverse procedure, , application of DDT followed by DMC at the same intervals was also used. Simultaneous appli- cations of DDT and synergist were used for comparison. In each case mortality counts were made 24 hours after application of the second compound. The results (Table III) indicate a marked decrease in mortality when applications of DDT and DMC were separated by 6 and 24 hours, irrespective of the order of application and as long as the dosage
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. 430 PERRY, MATTSON AND BUCKNER tervals before treatment with DDT. The reverse procedure, , application of DDT followed by DMC at the same intervals was also used. Simultaneous appli- cations of DDT and synergist were used for comparison. In each case mortality counts were made 24 hours after application of the second compound. The results (Table III) indicate a marked decrease in mortality when applications of DDT and DMC were separated by 6 and 24 hours, irrespective of the order of application and as long as the dosage of DDT was kept low. With the higher dosages of DDT it is evident that application of DDT followed by DMC at the indicated intervals was more effective than the reverse procedure. This may be explained on the as- CO o a: Q. 7 0- 65- 60- 55- 50- 45- 40- 3 5- 3 0-. 98 95 -90 -85 -80 -70 t D £ O -50 5 I- -40 2 LJ O -30 a: UJ Q. -20 -15 -10 -5 02 —I— 04 —I— 06 08 I -1— IO 20 —I— 40 60 DOSAGE Microgroms DDT Per Fly FIGURE 1. Probit-log dosage lines for adult female house flies (Roberds strain) ; DMC in micrograms per fly as indicated on the curves, plus various amounts of DDT applied topically to the ventral thoracic region. sumption that sufficient unchanged DDT was still present when the DMC was applied, especially at the 6-hour interval, to produce high synergistic activity. Since in all cases simultaneous applications of DDT and DMC showed greater ac- tivity than separate applications of the chemicals, an explanation of the cause of s\ nergistic action was sought in changes undergone by DMC after absorption. To test this hypothesis, groups of flies were given topical applications of DMC in the usual manner. At various intervals ranging from 2 to 72 hours after ex- posure the flies were sacrificed and analyses of external and internal DMC were made by the procedure described earlier. Table IV shows that 24 hours after ap- plication of micrograms DMC per fly,
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
