ORIENTAL FRUIT-FLY (DIPTERA, TEPHRITIDAE) RIPENING OF FRUIT AND ITS EFFECT ON INDEX OF INFESTATION OF HAWAIIAN PAPAYAS

Hawaiian papayas, Carica papaya L., were infested selectively by Dacus dorsalis Hendel at a 145.3-ha area in a commercial papaya orchard at Pohoiki, Hawaii, where the mean population density of the female fruit fly was ca. 992 flies per ha from November 1975 to October 1976. The infestation of papayas varied with ripeness, population densities of the new and old fruit flies, rainfall, and the minimum and maximum air temperatures during daytime. The significant factors were ripeness of papaya, population density of new members of D. dorsalis , and the maximum air temperature. Induced oviposition of papaya at 24.8°C decreased from 10.8 times in ripe fruit to 1.7 times in mature green fruit. The stadium of the 1st instar was lengthened by 1 to 2 days in green fruit. The result of the natural environmental factors, fruit fly behavior, and resistance of papayas was a low index of D. dorsalis infestation of 0, 0, 0, 0.06, or 3.85 larvae per fruit for a sample of 620 mature green, color-turning, quarter-, half-color, or ripe papayas, respectively.