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ARS Home » Southeast Area » Gainesville, Florida » Center for Medical, Agricultural and Veterinary Entomology » Insect Behavior and Biocontrol Research » Research » Publications at this Location » Publication #318846

Title: The role of the transformer gene in sex determination and reproduction in the tephritid fruit fly, Bactrocera dorsalis (Hendel)

item PENG, WEI - Huazhong Agricultural University
item WENPING, ZHENG - Huazhong Agricultural University
item Handler, Alfred - Al
item ZHANG, HONGYU - Huazhong Agricultural University

Submitted to: Genetica
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/23/2015
Publication Date: 11/9/2015
Citation: Peng, W., Wenping, Z., Handler, A.M., Zhang, H. 2015. The role of the transformer gene in sex determination and reproduction in the tephritid fruit fly, Bactrocera dorsalis (Hendel). Genetica. 143(6):717-727.

Interpretive Summary: Sterile insect technique programs (STI) for the control fruit fly pests can be improved by implementing male-only field releases. Finding new ways to separate sexes through the establishment of male-only strains for the oriental fruit fly, Bactrocera dorsalis, is a high priority by scientists at the Center for Medical, Agricultural and Veterinary Entomology, USDA Agricultural Research, Gainesville, Florida, and collaborators at international laboratories. Here we report the successful isolation and evaluation of two important sex determination genes that are active during embryonic development from the oriental fruit fly. Suppression of one of the genes by treatment with RNA interference results in the development of males from chromosomal female flies with no apparent effects on normal males. These findings are the first step showing proof of concept for production of male-only strains. The method described has potential use in production of a male-only population of the oriental fruit fly for use in SIT releases which will lead to reduced rearing costs and improved efficiency.

Technical Abstract: Transformer (tra) is a double-switch gene in the somatic sex-determination hierarchy that regulates sexual dimorphism based on RNA splicing in many insects. In tephritids, a Y-linked male determining gene (M) controls sex in the sex-determination pathway. Here, homologues of Drosophila tra and transformer-2 (tra-2) genes were isolated and characterized in Bactrocera dorsalis (Hendel), one of the most destructive agricultural insect pests in many Asian countries. Two male-specific and one female-specific isoform of B. dorsalis transformer (Bdtra)were identifed. The presence of multiple TRA/TRA-2 binding sites in Bdtra suggests that the TRA/TRA-2 proteins are splicing regulators promoting and maintaining, epigenetically, female sex determination by a tra positive feedback loop in XX individuals during development. The expression patterns of female-specific Bdtra transcripts during early embryogenesis shows that a peak appears at 15 h after egg laying. Using dsRNA to knock-down Bdtra expression in the embryo and adult stages,we showed that sexual differentiation is determined early in the embryo stage and that parental RNAi does not lead to the production of all male progeny as in Tribolium castaneum. RNAi results from adult abdominal dsRNA injections show that Bdtra has a positive influence on female yolk protein gene (Bdyp1) expression and fecundity.