Figure 1.

Secretions from the spinneret deposited on the leaf edge during feeding suppressed formation of green leaf volatiles. (A) A drawing of the head part of Bombyx mori larva (left top). A droplet was secreted from the spinneret after touching it with forceps (left bottom). Photos of a spinneret from Bombyx mori (right top) and the spinneret after ablation (right bottom) are shown. Bars are 50 µm. (B) Scanning electron micrographs of sections of mulberry leaves that were damaged by a silkworm with intact spinnerets (top) and a silkworm without spinnerets (bottom). (C) Amounts of volatile compounds emitted from mulberry leaves infested with silkworms with intact spinnerets (white bars) or without spinnerets (black bars). Compounds 1: (Z)-β-ocimene, 2: (E)-β-ocimene, 3: geranyl nitrile, 4: (Z)-3-hexen-1-yl acetate, 5: (Z)-3-hexen-1-ol, 6: unknown monoterpene 1, 7: unknown monoterpene 2, 8: (Z)-3-hexen-1-yl butanoate, 9: linalool, 10: α-farnesene, 11: methyl salicylate, 12: 2-methyl-3-buten-2-ol, and 13: (Z)-p-menth-2,8-dien-1-ol. Those identified by authentic compounds are underlined. Inset: amounts of (Z)-3-hexen-1-yl acetate and (Z)-3-hexen-1-ol quantified from corresponding calibration curves. Means with error bars are shown (SE, n = 5). Significant differences between the amounts of volatiles emitted after infestation with the intact and the ablated spinnerets are indicated by asterisks (*P < 0.05; **P < 0.01; Welch’s t-test).