MARKING OF HOST FRUIT BY MALE RHAGOLETIS-BOYCEI CRESSON FLIES (DIPTERA, TEPHRITIDAE) AND ITS EFFECT ON EGG-LAYING

Male Rhagoletis boycei flies (Cresson) have been shown previously to g uard egg-laying punctures on host walnut (Juglans major) fruit, During their tenure, R. boycei males were observed to dip the posterior port ion of their abdomen repeatedly toward the fruit surface, Closeup vide o analysis revealed that, during this dipping behavior, a clear viscou s substance emanating from the cercus was deposited directly on the fr uit. Laboratory assays indicated that the rate of abdomen-dipping was significantly higher on fruit bearing simulated egg-laying punctures t han on control fruit and significantly higher in the area of the punct ure than elsewhere on the fruit, In a final experiment, the occurrence of abdomen-dipping in the vicinity of a puncture was manipulated inde pendently on separate punctures on the same fruit. On such fruit and i n the absence of males, previously mated, reproductively mature female s attempted oviposition significantly more often in or near a puncture exposed to males than in or near an unexposed control puncture. Possi ble functions of the putative male-marking behavior from the perspecti ves of both male and female are discussed.