Fig. 5

Developmental changes in eggshell thickness during embryogenesis. The thickness of the chorion and the serosal cuticle was measured on the dorsal hatching line 180–200 μm (a) or 600–620 μm (b) from the tip or at a lateral non-hatching-line site 180–200 μm from the tip (c). The horizontal axis indicates stages of embryonic development with a scale reflecting typical developmental time (see Fig. 4a), except that the period of low temperature needed for diapause termination is not included (//). Lines connect the mean values of each point in development, and diamonds show individual values (N = 3–5). No serosal cuticle was present on Day 0 (*). Although the cuticle layer became recognizable at approximately Day 15–20, we did not quantify the thickness change until the start of diapause (broken line). Different letters indicate statistically significant differences among developmental stages (likelihood ratio test of a generalized linear model, P < 0.05), while N.S. indicates no significance (P > 0.05)