PRIOR EXPERIENCE AFFECTS THE VISUAL ABILITY OF RHAGOLETIS-POMONELLA FLIES (DIPTERA, TEPHRITIDAE) TO FIND HOST FRUIT

Females of the apple maggot fly, Rhagoletis pomonella, were allowed fo r 3 days to alight upon and oviposit in green or red 18- to 20-mm hawt horn host fruit (Crataegus mollis) or green or red 45- to 55-mm apple host fruit (Malus pumila) hung from branches of potted host trees in f ield enclosures. Subsequently, when females were released individually on potted host trees harboring fruit of one of these types, their abi lity to find fruit to unfamiliar size proved unaffected by prior exper ience with fruit but their ability to find fruit of unfamiliar color w as significantly affected. Specifically, females exposed to red hawtho rns or red apples were less able to find green hawthorns or green appl es than were females experienced with either of the latter fruit types . Fruit odor was found to have no effect on female ability to find fam iliar compared with unfamiliar green fruit. In contrast, a difference in size (or surface chemistry) between familiar and unfamiliar fruit b ut not a difference in fruit color had a significant negative influenc e on the propensity of alighting females to bore into unfamiliar fruit . Three bouts of experience with alighting upon and ovipositing into f ruit over a period of about 1 h had no detectable effect on female abi lity to find unfamiliar fruit but did reduce propensity to bore into u nfamiliar fruit. Our findings are discussed in relation to insect abil ity to learn visual and chemical stimuli of resources and insect prope nsity to form host races. We also discuss the potential impact of our findings on nonpesticidal, behavioral methods of managing R. pomonella in commercial apple orchards.