Comparison of food foraging behavior in the temperate apple maggot fly (Rhagoletis pomonella Walsh) and the tropical Mediterranean fruit fly (Ceratitis capitata Wiedemann).
The food foraging behavior of two frugivorous tephritid fruit flies, apple maggot fly (Rhagoletis pomonella Walsh) and the Mediterranean fruit fly (Ceratitis capitata Wiedemann) was compared by (1) assessing quantitatively fly feeding sites and activities over time and space in nature; (2) collecting substrates identified from feeding sites and assessing their contribution to fly maintenance and fecundity; (3) assessing fly intra-tree food-foraging behavior in field cages, as affected by food quality, and quantity. C. capitata feeding was studied in mixed orchards in Egypt and Greece. Females, dispersing and feeding more than males, foraged for food throughout most of the day requiring a substantial and varied diet that they often acquired away from the primary host. Feeding occurred at wounds and juice oozing from ripe fruits, as well on bird droppings. Male feeding on ripe fruit, occurred late in the day when they were least likely to find a mate. Fruit such as grapes did not support fecundity, contributing only to longevity, whereas fig fruit sustained longevity and fecundity. Bird feces added to a fig diet significantly increased fly fecundity. Apple maggot fly feeding was studied in an abandoned apple orchard in Massachusetts. Females, spend daily considerable time foraging for food on hosts and the surrounding vegetation, where they acquired food from foliage as well bird droppings. Fruit feeding played a minor role. Males remained mostly on fruiting host trees were they fed on leaf surfaces. Leaf surface bacteria did not support fly longevity or fecundity. Fly survival was sustained by leachates from host foliage, explaining the extensive grazing of flies there. Fly fecundity was sustained by bird droppings, supplemented by carbohydrates, as well as by aphid honeydew. Intra-tree fly foraging time was positively related to total amount of food solute previously encountered though largely independent of food volume or concentration. Volume and concentration, however, affected significantly food handling time and bubbling behavior, the oral extrusion of liquid crop contents to concentrate ingested food by elimination of excess water by evaporation. Weight losses of flies during post-feeding bubbling were an order of magnitude higher than when not bubbling
