Effects of Sterile Mediterranean Fruit Fly (Diptera: Tephritidae) Releases on the Target Species, a Nontarget Tephritid, and a Braconid Parasitoid (Hymenoptera: Braconidae) in Commercial Coffee Fields

A 2-yr program of sterile Mediterranean fruit fly, Ceratitis capitata (Wiedemann), releases (yr 1: 535 million; yr 2: 941 million flies) was conducted on Kauai Island, HI., in commercial coffee (Coffea arabica L.) fields. Fruit collections were used to estimate relative abundances of (1) C. capitata, the target species; (2) oriental fruit fly, Bactrocera dorsalis (Hendel), a potential competing fruit fly species; and (3) a beneficial wasp, Biosteres arisanus (Sonan), that attacks both fruit flies. During season 2, C. capitata abundance in the treatment area was suppressed by as much as 56% compared with the control area. In contrast, the number of B. dorsalis in treated coffee fields was within 6% of that in the control field for both years of the study, indicating that its abundance was not affected by C. capitata sterile releases. Numbers of B. dorsalis were not correlated with those of C. capitata, suggesting that these tephritids were not competitors in that habitat at that time. C. capitata and B. arisanus abundances were correlated positively in two of the four situations studied. Mean numbers of B. arisanus per 100 fruits in treated fields were 5.3 and 3.2 during seasons 1 and 2, respectively. Data suggest that high numbers of B. arisanus remain in a habitat inundated with sterile flies and that sterile C. capitata releases are compatible with B. arisanus parasitism for fruit fly control.