Response of the alfalfa seed chalcid, bruchophagus roddi, to alfalfa volatiles

KAMM, J.A.; BUTTERY, R.G.

Response of the alfalfa seed chalcid, bruchophagus roddi, to alfalfa volatiles

1983

KAMM, J.A. | BUTTERY, R.G.

An olfactometer was designed that permitted alfalfa seed chalcids [Bruchophagus roddi (Gussakovsky) Hymenoptera: Eurytomidae] to respond to volatiles in alfalfa, first by flight toward the source and then, after landing on the target, by close-range orientation. Females flew to targets with extracts of fresh alfalfa seed pods of flowers but not to extracts of leaves. At close range, ♀♀ oriented to extracts of seed pods or leaves but not to extracts of flowers. Among the volatiles that emanate from alfalfa, ♀♀ flew to octan-3-1 (E)-β-farnesene, 1-octen-3-ol, α-copaene, γ-muurolene, and (E)-2-hexenal at concentrations of 0.01% or less. These compounds probably play a role in selection of hosts and oviposition sites. At close range, ♀♀ walked to and some remained in the area treated with any of the forementioned compounds or caryophyllene, (Z)-3-hexenyl acetate, or farnesol. These latter compounds probably act only as short-range cues in selection of hosts and oviposition sites.

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