Aedeagal length of the Oriental fruit fly, Bactrocera dorsalis (Hendel) (Diptera : Tephritidae), and its sympatric species in Thailand and the evolution of a longer and shorter aedeagus in the parapatric species of B-dorsalis

To compare the aedeagal length of sympatric species of Bactrocera fruit fli es in Thailand, 340 specimens, which were collected with methyl eugenol tra ps from 7 localities, were examined. Based on aedeagal length and the costa l 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 aedeagu s with a discontinuous marking (LD, n = 2), a shorter aedeagus with a conti nuous 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 Inte rnational, Wallingford), males of the LC and SD groups were determined to b e 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 nar row costal marking different from the typical B. dorsalis. The aedeagal len gths (without distiphallus) differed significantly among the 3 groups (ANCO VA, 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. T he aedeagal length of one male of the LLD group was 4.17 mm. This male rese mbled B. tuberculata (Bezzi), but differed somewhat from the CABIKEY B. tub erculata. Thus, specimens of the SC, LD and LLD groups could not be accurat ely placed. The aedeagal length of B. dorsalis was compared with those of t he parapatric species, B. papayae and B. carambolae, and potential factors affecting a longer and shorter aedeagal length are discussed.