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Allozyme electrophoretic evidence for a complex of species within the Bactrocera tau group (diptera: Tephritidae) in Thailand
(2006-01-01)
Saelee, Anchalee
;
Tigvattananont, San
;
Baimai, Visut
Electrophoretic analysis of the Bactrocera (Zeugodacus) tau-like flies collected from wild populations coupled with morphological observation and cytological evidence has revealed seven species within this taxon, temporarily designated as species A (= B. tau s.s), C, D, E, F, G and I. These enzyme electrophoretic characteristics distinguishing these species (including four sympatric and two allopatric species) are described in this study. The value of Wright's fixation index, F<inf>ST</inf>, among populations was found to be +0.769. Partitioning of each species reduced the mean F<inf>ST</inf> to +0.053. This suggests strong species-specific mating. UPGMA clustering of Nei's unbiased genetic distance was estimated by analysis of allele frequencies at 12 enzyme loci. The resulting dendrogram shows that two lineages exist in the B. tau complex, one consisting of species C and I and the other comprising four species including B. tau s.s. (=A), species D, E, F and G. Of these, species F and G are truly sibling species because of their morphological similarity.
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Distribution of the Reproduction-modifying Bacteria, Wolbachia, in Natural Populations of Tephritid Fruit Flies in Thailand
(2000-06-01)
Kittayapong, Pattamaporn
;
Milne, John R.
;
Tigvattananont, Saen
;
Baimai, Visut
Wolbachia are bacteria that infect the reproductive tissues of numerous arthropod species, including tephritid fruit flies. These bacteria are potentially useful for management of tephritid fruit fly pest populations and may also influence tephritid speciation. The extent to which Wolbachia is distributed among tephritid fruit flies is currently unknown. We conducted a PCR-based survey from October 1995 to June 1998 to determine the prevalence and types of Wolbachia present in tephritid fruit flies in Thailand. Infected flies emerged from twenty of 126 fruit and flower collections and comprised 13 (of 46) species, twelve of which were in the genus Bactrocera. However, only 40% of individuals from infected populations, on average, were infected. Further, for infected species collected at numerous locations, less than one-half of locations had infected flies. Finally, 80% of infected collections were taken during just 3 months (October to December 1997) throughout the 33 month long survey. The use of PCR primers revealed that members of both A and B Wolbachia groups were present. They comprised the Aus subgroup (Group A), and the Con, Dei and Pip subgroups (Group B). Wolbachia from flies of nine collections could not be typed and may represent new subgroups, although there are other possibilities. Most flies carried a single subgroup of Wolbachia. Flies of two collections, however, were doubly infected. Our results indicate that Wolbachia prevalence and type varies substantially among and within tephritid fruit fly species. It is, therefore, crucial to understand the effects of these subgroups on tephritids as well as the factors that control Wolbachia prevalence before a role in pest management or speciation can be assessed for these bacteria.
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Metaphase karyotypes of fruit flies of Thailand. IV. Evidence for six new species of the Bactrocera dorsalis complex
(1999-01-01)
Baimai, Visut
;
Phinchongsakuldit, Jaros
;
Tigvattananont, Saen
Wild samples of larvae of 6 new fruit fly species belonging to the Bactrocera dorsalis complex have been temporarily designated as species I, J, K, L, M and N, based on cytological evidence. The flies are also morphologically distinguishable as adults. The larvae of these species seem to specifically infest fruits of different host plants. Cytological examination of larvae of these new species has revealed distinct patterns of metaphase karyotypes on the basis of different amounts and distribution of constitutive heterochromatin in sex chromosomes and autosomes. Thus the mitotic karyotype of species I is somewhat similar to that of B. dorsalis and is classified into Group 1. On the other hand, species L, M and N exhibit mitotic karyotypes of Group 4 showing specific patterns of heterochromatin in the centromeric regions of the X chromosome. Species J and K show a general feature of the mitotic karyotype of Group 3, which exhibits distinctive patterns of heterochromatin in sex chromosomes. These findings support the important role of constitutive heterochromatin in karyotypic evolution of these members of the B. dorsalis complex. Such a gross difference in heterochromatin is also a useful tool in cytotaxonomic study of closely related species of the fruit flies of Thailand.
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METAPHASE KARYOTYPES OF FRUIT FLIES OF THAILAND II. FIVE SPECIES IN FOUR SUBGENERA OF BACTROCERA
(1996-06-01)
Baimai, Visut
;
Trinachartvanit, Wachareeporn
;
Tigvattananont, Saen
;
Grote, Paul J.
Five species of fruit flies of the genus Bactrocera (Diptera, Tephritidae) collected from natural populations at different localities in Thailand were examined cytologically. They showed distinctive metaphase karyotypes with respect to the amount and distribution of constitutive heterochromatin in centromeric regions of autosomes and sex chromosomes. Bactrocera (Hemigymnodacus) diversa, B. (Bactrocera) latifrons and B. (Asiadacus) modica, three distinct species belonging to different subgenera, clearly exhibited different pericentric heterochromatin in all autosome pairs. The large metacentric X chromosome and conspicuous blocks of heterochromatin of B. (B.) latifrons makes it distinctive from B. (A.) modica and B. (H.) diversa. Further, B. (Z.) rubella and B. (Z.) scutellaris belong to the same subgenus Zeugodacus, but they have different metaphase karyotypes based on the amount of centromeric heterochromatin in all autosomes. The X and Y chromosomes of B. scutellaris are much longer than those of Z. rubella due to accumulation of large quantities of heterochromatin. Such cytological differences among these distinct species are very useful as diagnostic characters in cytotaxonomic studies and may provide information concerning chromosomal evolution of these important pests in Thailand.

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