ATTRACTION OF MATURE CERATITIS-CAPITATA FEMALES TO 2-HEPTANONE, A COMPONENT OF COFFEE FRUIT ODOR

In indoor laboratory-cage and outdoor field-cage assays, we evaluated the attraction of released, protein-fed, mature Mediterranean fruit fl y females to six volatile compounds emitted by attractive crushed ripe coffee fruit: 3-methyl-1-butanal, decanal, 3-methyl-1-butanol, 2-(Z)- pentenol, 2-(E)-hexenol, and 2-heptanone. Previous tests in a wind tun nel indicated that each of these six compounds was more attractive tha n clean air to females. In laboratory cage assays, none of the compoun ds elicited a response significantly greater than that to water. In fi eld-cage assays, 2 or 4 mu l of 2-heptanone in 5 mi of water (but none of the other compounds at 2 or 4 pi in 5 mi of water) consistently at tracted protein-fed medflies at significant levels that averaged about five times greater than attraction to water alone, although about 40% less than attraction to odor of coffee fruit extract. All types of ma ture protein-fed females tested (laboratory-cultured virgin, laborator y-cultured mated, wild mated) in field-cage assays responded similarly to 2-heptanone, whereas same-age (9- to Ii-day-old) protein-deprived females did not respond significantly to 2-heptanone. Response of prot ein-fed females to 2-heptanone increased progressively with increasing dose (1, 2, 4, or 8 mu l in 5 mi of water). Addition of 2 mu l of 2-h eptanone or 2 mu l of any of the other compounds tested to 5 mi of wat er extract of coffee fruit did not enhance attractiveness of the extra ct. Relative to response to water, protein-fed females consistently ex hibited a significant positive response to odor of coffee fruit extrac t but no significant response to odor of Nulure (a proteinaceous food attractant). Together, our findings suggest that mature protein-fed fe males were responding to 2-heptanone as though it were an oviposition- site stimulus rather than a feeding-site stimulus.