Length of Larval Period Related to DDT-Resistance in Drosophila12

Abstract

The larvae of D. melanogaster lines selected for short (SL) and long (LL) larval period were assayed for DDT.resistance by adding to the larval medium known amts. of p, p-DDT dissolved in carbon tetrachloride. Assays were made after 28, 29, 39, 46, and 52 generations of selection. A non-selected (CS) line was also assayed each generation as a control. Data were analyzed on a separate generation basis and also for all generations pooled. Based on LD50 values, the SL line was more susceptible to DDT-poisoning than either of the other lines. No difference in DDT-resistance was found between the CS and LL lines. Although no difference in slope of the dosage mortality regression line was found between the CS and LL lines, the dosage mortality regression line was steeper in the SL line than in the CS or LL lines, indicating a difference in reaction to the toxicant.