EFFECTS OF RECENT EXPERIENCE ON FORAGING IN TEPHRITID FRUIT-FLIES

Infield-cage studies, we investigated how the foraging behavior of tep hritid fruit flies is modified by experience immediately prior to rele ase on host plants. We observed females of a relatively monophagous sp ecies. Rhagoletis mendax (blueberry maggot fly), an oligophagous speci es, Rhagoletis pomomella (apple maggot fly), and a polyphagous species , Ceratitis capitata (Mediterranean fruit fly). Just prior to release on a host plant, the following kinds of stimuli were supplied: (1) sin gle oviposition in a host fruit, (2) contact with 20% sucrose, 3) cont act with a mixture of protein food (bird feces and sucrose), (4) conta ct with water, and (5) a walk over a host-plant leaf. When flies forag ed on host plants without resources, search was most intensive (as mea sured by number of leaves visited) following a single oviposition in f ruit, but residence time generally was the same following exposure to sugar, protein, and fruit stimuli. Rhagoletis mendax and C. capitata f emales visited the fewest leaves following exposure to wader or host l eaves, whereas R. pomonella foraged equally intensively following expo sure to food stimuli, water, or leaves. On host plants containing reso urces (fruit and protein food), a single oviposition dramatically incr eased the number of females of all three species that found fruit comp ared to females that received experience with food, water or foliar st imuli. We found no significant effect of recent brief experience with any of the stimuli on subsequent attraction to protein food. Overall, C. capitata exhibited a higher propensity to abandon host plants than either R. mendax or R. pomonella. We suggest that this may reflect ada ptations to differences in distribution of host plants in nature, stra tegies of dispersal, and host range.