COLONIZATION OF NEWLY PLANTED COFFEE FIELDS - DOMINANCE OF MEDITERRANEAN FRUIT-FLY OVER ORIENTAL FRUIT-FLY (DIPTERA, TEPHRITIDAE)

Previous studies in Hawaii indicated that Ceratitis capitatat (Wiedema nn), Mediterranean fruit fly, became scarce at low elevations subseque nt to accidental introduction of Bactrocera dorsalis (Hendel), orienta l fruit fly. The conclusion was that competitive displacement: elevati on, and parasites were major determinants in the ranges of these two f ruit nics. Recently, commercial coffee, Coffea arabica L., was planted in former sugarcane, Saccharum officinarum L., fields at an elevation of 122 m on Kauai Island, HI. During a 3-yr period we studied coloniz ation of fruits by C. capitata, B. dorsalis, and Biosteres arisamus (S onan), a beneficial solitary wasp that attacks both species of fruit f lies. During seasons 1 and 2, mean numbers of C. capitata were greater than those of B. dorsalis. Lack of an inverse correlation between num bers of the two tephritids emerging from fruits suggested that these s pecies were not competitors. B. arisanus parasitization rates on tile basis of live and dead parasitoids recovered from C. capitata and B. d orsalis pupae were modest. Studies during season 3 indicated B. arisan us parasitization rates were higher for C. capitata than those for B. dorsalis. Numbers of C. capitata and B. arisanus were correlated durin g both seasons, suggesting a density-dependent relationship between th e most abundant host and tile parasitoid. Fruit infestation data demon strated that C. capitata exploits fruits at an earlier ripeness stage and emerges sooner from fruits than B. dorsalis. Analysis of three ann ual coffee crops indicated that C. capitata was the dominant fruit fly species in the coffee agroecosystem by the end of the season. This fi nding differs from previous studies, wherein B. dorsalis was dominant over C. capitata at low elevation.