Exocrine Secretions of Wheel Bugs (Heteroptera: Reduviidae: Arilus spp.): Clarifi cation and Chemistry

摘要

Wheel bugs (Heteroptera: Reduviidae: Harpactorinae: Arilus) are general predators, the females of which have reddish-orange subrectal glands (SGs) that are eversible like the osmeteria in some caterpillars. The rancid odor of Arilus and other reduviids actually comes from Brindley's glands, which in the North (A. cristatus) and South (A. carinatus) American wheel bugs studied emit similar blends of 2-methylpropanoic, butanoic, 3-methylbutanoic, and 2-methylbutanoic acids. The Arilus SG secretions studied here are absolutely speciesspecifi c. The volatile SG components of A. carinatus include (E)-2-octenal, (E)-2-nonenal,(E)-2-decenal, (E,E)-2,4-nonadienal, (E)-2-undecenal, hexanoic acid, 4-oxo-nonanal,(E,E)-2,4-decadienal, (E,Z)-2,4- or (Z,E)-2,4-decadienal, and 4-oxo-(E)-2-nonenal; whereas in A. cristatus the SG secretion contains β-pinene, limonene, terpinolene, terpinen-4-ol, thymol methyl ether, α-terpineol, bornyl acetate, methyl eugenol, β-caryophyllene, caryophyllene oxide, and farnesol. Arilus spp. SG secretions may be sex pheromones, but verifi cation of this hypothesis requires further testing.