Abstract
The aedeagal length, body size and number of pecten setae of the peach fruit fly, Bactrocera zonata, in Egypt were measured and compared with the sympatric species, B. dorsalis and B. correcta in Thailand. The body size of B. zonata was intermediate between B. dorsalis and B. correcta, with some overlap at each end. Aedeagal length of B. zonata was also intermediate between B. dorsalis and B. correcta, with no overlap. These results indicate that the 3 sympatric species can be distinguished by measurement of the aedeagal length. Because B. zonata recently invaded Egypt, it was expected that variability of morphological traits of this population would be smaller than what might be found in an indigenous Bactrocera population. However, coefficients of variation (CV) for body size, aedeagal length and number of pecten setae were similar to those for an indigenous population of B. correcta, indicating that the founder B. zonata population in Egypt had already acquired significant variation in these traits despite having passed through a presumed bottleneck situation. It was remarkable that the CV for aedeagal length was less than one half that for other traits, supporting the notion of stabilizing selection.
