Figure 1.

Antennal morphology is preserved in domesticated males but not in females. (a) Wild silkmoths B. mandarina, domesticated silkmoths B. mori and hybrids of both were studied. (b) Schematic of a silkmoth's head with its left antenna; the bold line represents the antennal stem; thin lines perpendicular to the stem denote branches. The black frame marks the middle branch where olfactory sensilla were counted. (c) Close-up view of long trichoids (arrowheads) and sensilla basiconica (arrows) of a female B. mori; scale bar, 2 µm. (d) Frequency of olfactory sensilla on the middle antennal branch of males (solid line) and females (dotted line); size ranges of medium-length trichoids and sensilla basiconica broadly overlap [2], so the numbers of these two sensillum types were pooled. The middle antennal branch was chosen because sensillum numbers and their ratios are constant in the middle region of the antenna of B. mori, irrespective of the size of the animal [2]. Symbols represent data from individual silkmoths; the diagonal separates animals that have more long trichoids than sensilla basiconica and medium-length trichoids (above the diagonal) from animals with the reverse sensillum ratio (below the diagonal). The sensillum ratios for B. mori are in accordance with ratios from data based on an estimation of sensillum numbers of the whole antenna [2]. (e) Detail of a middle antennal branch of a B. mandarina female (i) and a B. mori female (ii); scale bar, 20 µm.