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Free keywords:
agrotis segetum
turnip moth
sex pheromone
(z)-5-decenyl acetate
(z)-7-dodecenyl acetate
(z)-9-tetradecenyl acetate
(z)-5-dodecenyl
acetate
electrophysiology
single-sensillum recordings
receptor
neuron
flight tunnel
field tests
small ermine moths
multicomponent pheromones
chemical communication
heliothis-virescens
helicoverpa-zea
trichoplusia-ni
flight tunnel
noctuidae
lepidoptera
responses
Abstract:
In addition to the pheromone components (Z)-5-decenyl, (Z)-7-dodecenyl and (Z)-9-tetradecenyl acetate (Z5-10:OAc, Z7-12:OAc and Z9-14:OAc), it has previously been shown that the sex pheromone gland of the turnip moth, Agrotis segetum (Lepidoptera: Noctuidae Schiff) contains 10:OAc, 12:OAc, Z5-12:OAc, Z9-12:OAc, 11-12:OAc, Z5-14:OAc, Z7-14:OAc and Z11-16:OAc. To find out whether any of these additional compounds is involved in the sex pheromone communication in A. segetum, a comprehensive electrophysiological and behavioural investigation was conducted. Single-sensillum recordings on male antennae revealed three subtypes of sensilla among the previously so-called Z5-10:OAc sensilla. One subtype was identified having one receptor neurone (A) that responded to Z5-10:OAc with a large spike amplitude and another neurone (B) that responded to (Z)-5-decenol (Z5-10:OH) with a small spike amplitude. In another subtype the B neurone responded to Z5-12:OAc and sometimes also to Z7-12:OAc and 10:OAc, in addition to responding to Z5-10:OH. In a third subtype the A neurone responded to all acetates identified from the female pheromone gland, whereas the small. spike amplitude neurone was tuned to Z5-10:OH. A flight tunnel assay showed that blends composed of nine, eight or seven compounds were equivalent to the previously identified three-component pheromone blend in eliciting male behavioural responses. In field trapping tests, blends of eleven, nine or seven compounds did, however, catch significantly more moths than the three-component blend. Further assays showed that only Z5-12:OAc could significantly increase the catch numbers when added to the three-component blend, and thus qualified as a fourth pheromone component in A. segetum. The behavioural significance of additional female-produced acetates - for which males possess antennal receptors - is suggested, but may be impossible to confirm because of 'diminishing returns' when trying to refine a multicomponent pheromone further.
