Formation of second-generation free-living larvae in Strongyloides stercoralis requires 24–48 hours of exposure to Δ7-dafachronic acid.

Frequency of development to second-generation free-living rhabditiform L3 and L4 (FL L3-L4) in S. stercoralis was plotted as a function of duration of exposure to increasing concentrations of Δ7-dafachronic acid (Δ7-DA). Ascending shaded triangles indicate that developmental frequencies were determined at Δ7-DA concentrations of 125 nM (lightest), 250 nM, 500 nM, and 1,000 nM (darkest). Bar height represents the mean of three biological replicates; error bars represent +1 standard deviation. The overall effects of Δ7-DA exposure duration and concentration were significant, P < 0.0001. For all possible pairwise statistical comparisons of FL L3-L4 frequency with DA exposure durations of 24, 48, and 72 hours, ** P < 0.01; *** P < 0.001.