Figure 2. D. suzukii shows a weaker egg-laying preference than D. melanogaster for sweeter substrates.

(A) The single-fly egg-laying preference paradigm. The preference index is calculated as (#eggs in higher sugar concentration - #eggs in lower sugar concentration)/total #eggs. (B–D) Preference indices for the indicated concentrations of (B) sucrose, (C) fructose, and (D) glucose. Each egg-laying preference index was compared to 0 using the Wilcoxon signed-rank test. The Mann-Whitney test was used to compare the preference indices between species. n=18–20. ns, not significant; *p<0.05; **p<0.01; ***p<0.001; ****p<0.0001. Error bars are SEM.

Figure 2—figure supplement 1. Preferences for high-sugar concentrations are not exclusively due to a preference for high osmolarity.

The egg-laying preference for sucrose vs. sorbitol, a sugar alcohol considered tasteless to the fly. The preferences are the same as between sucrose and plain agarose (taken from Figure 2B). Each egg-laying preference index is compared to 0 using the Wilcoxon signed-rank test. The Mann-Whitney test is used to compare the preference indices between species. n=18–20. ns, not significant; *p<0.05; **p<0.01; ***p<0.001; ****p<0.0001. Error bars are SEM.