A total of 1510 specimens was collected in traps (566 specimens in cue-lure, and 895 in methyl eugenol) or by hand with a net or vial (53 specimens). These belonged to 14 species, listed below. Genomic DNA was extracted from a leg and genetic sequencing of the mitochondrial gene cytochrome c oxidase I (COI, 780 bp) was performed on 62 specimens, covering every species collected during the survey, following the methods described by San Jose et al. (2013). Sequences were compared with existing sequences, whenever available, to help confirm species identity. Pinned voucher specimens of all species were deposited in the University of Hawaii Insect Museum (Honolulu) and the Institute of Food and Radiation Biology of the Bangladesh Atomic Energy Commission (Dhaka). Bactrocera (Bactrocera) dorsalis (Hendel) (oriental fruit fly) [AERE: 165 specimens, INST: 78, BNP: 27, MNP: 2, Jamalpur: 1, RNPP: 208, Gurudaspur: 52, RHRC: 333. Methyl eugenol]. Oriental fruit fly was by far the most numerous species among all samples, with 57% of all collected flies. Recorded hosts in Bangladesh include mango (Mangifera indica L.), carambola (Averrhoa carambola L.), and guava (Psidium guajava L.) (Kabir et al. 1991).
This species exhibits in Bangladesh a broad range of scutum color pattern variation. The large series collected in RHRC was carefully examined and scutum and abdomen color of each specimen was assigned to one variant category, ranging from predominantly pale to predominantly dark. The proportion of specimens with each scutum color category, among the 326 specimens examined, was 7.4% in category A, 15.0% in B, 17.2% in C, 4.0% in D, 17.5% in E, 4.3% in F, 19.3% in G, and 15.3% in H. The proportion in each abdomen color category was 3.7% in category A, 32.2% in B, 50.3% in C, 12.6% in D, and 1.2% in E. The scutum color gradient, from lightest to darkest, was also correlated to a large extent with the lightest to darkest abdomen color gradient (graph insert on Fig. 2). The scutum pattern variation is similar to that documented in B. invadens Drew, Tsuruta and White, suggesting that the variation observed in B. invadens is not restricted to native Sri Lankan and invasive African populations, but more widespread on the Indian subcontinent, explaining the presence of B. invadens in Bhutan reported by Drew et al. (2007). To explore the relationship of Bangladesh B. dorsalis with related species in the complex, we sequenced the COI gene of 8 specimens of B. dorsalis (with scutum and abdomen color combinations B-B, B-C, B-D, C-C, G-D, H-D, E-C, and H-E) and 8 specimens of B. invadens, one of each scutum variant, collected in 2010 in Burkina Faso, and compared them to the sequences published in San Jose et al. (2013). The proportion of each color category, among 566 specimens from Burkina Faso, was 6.2% in category A, 7.8% in B, 13.1% in C, 2.6% in D, 16.8% in E, 21.7% in F, 16.8% in G, and 15.0% in H. The eight sequences were deposited in GenBank (www.ncbi.nlm.nih.gov) (see appendix), and analyzed with GARLI (Zwikl 2006) using the same model and with the same sequences included in the COI phylogeny from San Jose et al. (2013).
In the phylogenetic tree resulting from the analysis, all the individuals of B. dorsalis from Bangladesh and B. invadens from Burkina Faso were placed within the B. dorsalis sensu lato clade, which also included B. papayae Drew and Hancock, B. carambolae Drew and Hancock, and B. philippinensis Drew and Hancock. Our analysis and other recent studies (Ekesi and Mohammed 2010, Khamis et al. 2012, San Jose et al. 2013, Schutze 2013) suggest that the two species are genetically identical, produce viable offspring in the lab, and that B. invadens may just be a geographic color variant of B. dorsalis. In his original revision of the species complex (Drew and Hancock 1994), R.A.I. Drew listed B. dorsalis as widespread in Asia, from India to Taiwan. More recently (Drew and Romig 2013), he could not confirm the Bhutan record of B. invadens or the occurrence of B. dorsalis in India and Sri Lanka. In any case, whether regarded as a color variant of B. dorsalis or a separate species, the light colored form consistent with B. invadens is shown here to be relatively widespread over the Indian subcontinent rather than confined to Sri Lanka.
Bactrocera (Bactrocera) latifrons (Hendel) (solanum fruit fly) [AERE: 11 specimens, all collected by hand]. New record for Bangladesh. A pest of Solanaceae, widespread in tropical Asia, from India to Taiwan, and south to peninsular Malaysia. Bactrocera (Bactrocera) nigrofemoralis White and Tsuruta [AERE: 2 speci- mens, Gurudaspur: 1, RHRC: 1. Cue-lure]. New record for Bangladesh. A common species in Sri Lanka, India, Pakistan, and Bhutan, bred from five species of edible fruits (Tsuruta and White 2001, Drew and Romig 2013).
Bactrocera (Bactrocera) rubigina (Wang and Zhao) [AERE: 79 specimens, BNP: 56. All but two females from cue-lure]. New record for Bangladesh. Originally described from China (Wang and Zhao 1989) and later recorded from Bhutan, Thailand and Vietnam (Drew et al. 2007, Drew and Romig 2013). A non-economic species bred from Litsea verticillata Hance in China (Liang et al. 1993).