To compare the aedeagal length of sympatric species of Bactrocera fruit flies in Thailand, 340 specimens, which were collected with methyl eugenol traps from 7 localities, were examined. Based on aedeagal length and the costal marking at the apex of the wing, males were divided into 5 groups, i.e., a longer aedeagus with a continuous marking (LC, n=233), a longer aedeagus with a discontinuous marking (LD, n=2), a shorter aedeagus with a continuous marking (SC, n=7), a shorter aedeagus with a discontinuous marking (SD, n=97), and a very long aedeagus with a discontinuous marking (LLD, n=1). Using the CABIKEY (White and Hancock, 1997, Windows CD-ROM, CAB International, Wallingford), males of the LC and SD groups were determined to be B. dorsalis (Hendel) and B. correcta (Bezzi), respectively. The SC group was similar to B. dorsalis; however, all males of this group had a very narrow costal marking different from the typical B. dorsalis. The aedeagal lengths (without distiphallus) differed significantly among the 3 groups (ANCOVA, F=307.02, p<0.0001): the LC group (2.727±0.111 mm, mean±SD), the SC group (2.201±0.065 mm) and the SD group (2.063±0.075 mm). The aedeagal length of the LD group was 2.33–2.34 mm. This group resembled B. zonata (Saunders), however; they differed from the CABIKEY B. zonata in possessing a very small spot-like costal marking at the apex of the wing. The aedeagal length of one male of the LLD group was 4.17 mm. This male resembled B. tuberculata (Bezzi), but differed somewhat from the CABIKEY B. tuberculata. Thus, specimens of the SC, LD and LLD groups could not be accurately placed. The aedeagal length of B. dorsalis was compared with those of the parapatric species, B. papayae and B. carambolae, and potential factors affecting a longer and shorter aedeagal length are discussed.
2001 by the Japanese Society of Applied Entomology and Zoology