POTENTIAL FOR HOST-RANGE EXPANSION IN CERATITIS-CAPITATA FLIES - IMPACT OF PROXIMITY OF ADULT FOOD TO EGG-LAYING SITES

1. In field cage and field tests, female Mediterranean fruit flies, Ce ratitis capitata (Wiedemann), in trees alighted in significantly great er numbers upon sticky-coated (non-odour-emitting) kumquats, Fortunell a japonica, that were in the vicinity of odorous natural proteinaceous food (bird faeces) or synthetic food odour than on similar kumquats d istant from bird faeces or synthetic food odour. 2. In field cage test s, oviposition in non-sticky kumquats nearby bird faeces was significa ntly greater than in non-sticky kumquats distant from bird faeces. 3. In field tests, medflies laid significantly more eggs in host kumquat and non-host hawthorn, Crataegus mollis, fruit adjacent to bird faeces and synthetic food odour than in fruit of these types distant from fo od-type stimuli. 4. These findings suggest that odour of natural food of medflies could lure flies to plants whose fruit emit little or no a ttractive odour and are not permanent hosts but which are nonetheless susceptible to egg-laying and larval development, resulting in tempora ry expansion of host range.