Identification of apple volatiles attractive to the apple maggot,Rhagoletis pomonella

Apple volatiles from whole Red Delicious and Red Astrachan apples were found to be attractive to sexually mature apple maggot flies,Rhagoletis pomonella (Walsh), in wind tunnel bioassays. Extracted volatiles elicited directed upwind movement towards the source and significantly increased the number of male and female flies arriving at the source. A behaviorally active fraction was obtained from crude extract by gas-liquid chromatography and assayed in two types of wind tunnels and by electroantennography. The major components in this fraction, identified by chemical derivatization reactions and GLC-mass spectrometry, were hexyl acetate, (E)-2-hexen-1-yl acetate, butyl 2-methylbutanoate, propyl hexanoate, hexyl propanoate, butyl hexanoate, and hexyl butanoate in a 35∶2 8∶12∶5∶28∶10 ratio. Synthetics of the identified compounds and the natural extract elicited similar behavioral and EAG responses. None of the synthetics or natural components elicited full activity when presented alone.