Attractiveness of synthetic corn volatiles to feral northern and western corn rootworm beetles (Coleoptera: Chrysomelidae)

Synthetic corn volatiles and selected analogues were tested in corn fields for attractiveness to feral adults of northern corn rootworm, Diabrotica barberi Smith & Lawrence, and western corn rootworm, Diabrotica virgifera virgifera LeConte. Attractiveness of test compounds was compared with that of reference standards, geranylacetone and (+)-alpha-terpineol for northern and western corn rootworm, respectively, and with two structural isomers of the reference standards, nerylacetone and (+)-alpha-terpinen-4-ol, which were the only test compounds not reported from corn. Compounds attracting to northern corn rootworms included nerylacetone, linalool, and geranyl acetate, although the best captures were only approximately 20% of those on traps baited with the geranylacetone reference standard. Linalool proved to be an effective western corn rootworm attractant that captured as many females as the (+)-alpha-terpineol reference standard. Methyl salicylate also showed moderate attractiveness to western corn rootworm females. Marginal captures (but statistically higher than control) of western corn rootworm females occurred on traps baited with nerylacetone, geranyl acetate, geraniol, and (-)-alpha-pinene. Linalool was the only new compound to attract western corn rootworm males, but the highest capture was only about twice that of control. Compounds that failed to attract either species or sex in numbers significantly exceeding control were (+)-alpha-terpinen-4-ol, (+)-alpha-pinene, carvacrol, thymol, and 1-octen-3-ol. Kairomonal attractants so far identified for corn rootworm adults generally are widely distributed in nature and thus unlikely to account for specificity of host-finding responses except as components of unique odorant blends.