Electroantennogram activity and attraction assay of Ceratitis capitata to airborne volatiles from peach at three ripeness stages.

Several components present in airborne volatiles produced by peaches at thr ee stages of ripeness were identified. Some of these evolved from one ripen ess stage to another. For example, ethanal (methyl phenyl) was detected in green fruits and became part of the ketone (metylphenyl) series of green ri pe fruits; 3-ethyl-5-methyl benzyl alcohol detected in green ripe fruits be came 4-isopropyl benzyl alcohol when these fruits ripened; 4-ethyl acetophe none appeared in all three stages. An increase in the concentration of este rs was observed as ripeness developed. Electroantennogram studies using Cer atitis capitata (Wied,) males and females showed that the most active compo unds were ethyl octanoate; naphthalene; 1,2,3,4-tetrahydronaphthalene; 4-et hyl acetophenone and ethyl ethyl benzoate. Males and females responded diff erently to 1,2,3,4-tetrahydronaphthalene and 4-ethyl acetophenone. The enti re airborne volatile fraction from peach gave a higher electroantennogram r esponse than any of its individual components. These components gave a grea ter response when peaches were at the green-ripe stage. In all of the tests , female C. capitata individuals were more responsive than males. In attrac tion assays, female response was greater to those compounds that gave the h ighest signals in the electroantennogram studies with the exception of 4-et hyl acetophenone.