Behavioural responses of the carrot fly larva, Psila rosae, to carrot root volatiles |
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Authors: | M. F. RYAN P. M. GUERIN |
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Affiliation: | Department of Zoology, University College, Dublin, Ireland |
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Abstract: | ABSTRACT. The behaviour of the carrot fly larva, Psila rosae F. (Diptera, Psilidae), was investigated in the presence of six concentrations of thirty-four volatiles associated with carrot root and of trans -methyl-iso-eugenol, a constituent of carrot herb oil. Bomyl acetate, 2,4-dimethyl styrene, α-ionone, SbT-ionone and biphenyl were the most consistently preferred compounds. Klinotaxis and klinokinesis were the orientation responses near the stimulus source. Trans -2-nonenal was the most consistently avoided compound. Extracts derived by steam distillation of carrot roots and by concentration of vapour from roots were resolved, by gas liquid chromatography, into forty-five and twenty-two major constituents, respectively. The five preferred compounds are micro-components of these extracts, collectively representing 1% and 0.6% of root extract oil and vapour, respectively. It is suggested that these secondary plant constituents are specific host finding cues for the larva, and that frara-2-nonenal is a carrot defence compound. |
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Keywords: | Carrot root fly Psila rosae olfaction host finding behaviour orientation carrot odour |
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