SENSITIVITY OF DETECTION TRAPPING SYSTEMS FOR MEDITERRANEAN FRUIT-FLIES (DIPTERA, TEPHRITIDAE) IN SOUTHERN CALIFORNIA

Release-recapture studies were conducted in southern California to determine the probability of capturing Mediterranean fruit flies, Ceratitis capitata (Wiedemann), in standard trapping arrays used to detect and delimit introduced populations. Two tests were conducted in a 10.4-km(2) area of Orange County that contained a total of 40 trimedlure-baited Jackson traps (10 traps per 2.6 km(2) [1 square mile]). Radiosterilized flies were marked with one of four colors and released at four different distances from each trap. Numbers of flies released at each point were adjusted so that the nominal density throughout the test area was 25 (first trial) or 12 (second trial) flies per hectare. In both trials, percentage of flies recaptured was approximate to 0.6% overall and, in general, was related inversely to the distance from the release site to the trap. In other tests, 23-27% of flies were recovered when released in Orange County within 0.26-km(2) plots that contained 100 trimedlure-baited yellow sticky panels. Using results of these and a previously published study, simple mathematical models based on binomial probability theory indicate that arrays of 10 Jackson traps per 2.6 km(2) would detect high proportions of relatively small, stable infestations of C. capitata within several generations. Arrays of 1,000 yellow panel traps per 2.6 km(2) essentially would detect all viable infestations within one generation and provide a sensitive tool for confirming eradication after treatment of infested areas.