Figure 1. Inhibition of Notch signalling promotes ovary activation.

(a) Proportion of bees scored as reproductively inactive (score=0), and degrees of reproductively active (score=1–3) following treatment of newly emerged bees for 10 days with 1 mM DAPT (n=324) or solvent control (n=321). Representative examples of the morphological differences seen between ovary scores are shown beneath the graphs. Treating newly emerged bees for 10 days with DAPT during mid-summer results in a significant decrease in the number of bees that are reproductively inactive (score=0, 69% reduced to 51%) and a significant increase in the number of bees that are actively laying eggs (score=3, 5% to 14%). Experiments were performed in triplicate on three separate occasions. (b) Proportion of bees scored as reproductively inactive (score=0), and degrees of reproductively active (score=1–3) following treatment of newly emerged bees for 10 days with solvent control (n=351), QMP and solvent control (n=378) or QMP and 1 mM DAPT (n=555). In late summer/early autumn there is a higher level of ovary activity in solvent-only treated bees (28% actively laying eggs, compared with 5% in mid-summer, consistent with reported seasonal variation in ovary activity⁴⁰. Exposing these bees to synthetic queen pheromone reduced this ovary activity significantly (compare white bars and dark bars), with the proportion of bees actively laying eggs (score=3) reduced from 28 to 5%), this inhibition was partially overcome by treatment with DAPT (compare dark bars with light grey bars) and the proportion of bees actively laying eggs increased significantly from 5 to 16%. Experiments with QMP were performed in triplicate on two separate occasions. Error bars are 95% confidence intervals, *non-overlapping 95% confidence intervals.