Attractiveness of synthetic volatile blends of flowering rice panicles to Trigonotylus caelestialium (Kirkaldy) (Heteroptera: Miridae)

The attractiveness of 22 synthetic volatile blends or seven individual chemicals emitted from flowering rice panicles to a rice leaf bug, Trigonotylus caelestialium (Kirkaldy), were investigated with an olfactometer to identify the active compounds responsible for the invasion of the bugs into paddy fields. n-Decanal attracted only male bugs, whereas β-caryophyllene attracted only females. β-Elemene repelled males and methyl benzoate marginally repelled females. The other chemicals did not attract or repel male and female bugs at all. Two-, 3-, 4- and 5-component blends of β-caryophyllene, n-decanal, n-tridecene, methyl salicylate and geranyl acetone were attractive to neither females nor males. Two-component blends comprised of β-caryophyllene and methyl salicylate, or n-decanal and methyl salicylate, marginally repelled females. The three-component blend comprised of β-caryophyllene, n-decanal and geranyl acetone marginally repelled females. The five-component blend comprised of β-caryophyllene, n-decanal, n-tridecene, methyl salicylate and geranyl acetone repelled males. The seven-component blend comprised of β-caryophyllene, n-decanal, n-tridecene, methyl salicylate, geranyl acetone, methyl benzoate and β-elemene attracted female bugs and marginally attracted male bugs. Six-component blends without any one of these seven components were not attractive to the bugs although the six-component blend without n-decanal was marginally attractive to females. The six-component blend without n-tridecene repelled males. These findings suggest that mixtures of these seven compounds play an important role in the attractiveness of flowering rice panicles to both sexes of the bugs, although the attractiveness of individual compounds differs between sexes.