Submitted to: Molecular Biology Reports
Publication Type: Peer reviewed journal
Publication Acceptance Date: 5/5/2010
Publication Date: 1/15/2011
Citation: Margam, V.M., Coates, B.S., Ba, M.N., Sun, W., Binso-Dabire, C.L., Baoua, I., Ishiyaku, M.F., Shukle, J.H., Hellmich II, R.L., Covas, F.G., Ramasamy, S., Armstrong, J., Pittendrigh, B.R., Murdock, L.L. 2011. Geographic distribution of phylogenetically-distinct legume pod borer, Maruca vitrata (Lepidoptera: Pyraloidea: Crambidae). Molecular Biology Reports. 38(1):893-903. Interpretive Summary: Species of moths feed upon fruit- and seed-bearing portions of crop plants, and pose problems to producers worldwide. Control of pest insect species in developing nations and sub-tropical regions of the United States are especially difficult due to continual insect pressure for most of the crop growing season. Understanding insect pest biology and ecology will assist in devising ecologically friendly methods of control, and will be useful to growers of genetically-engineered crops in developing nations. To address these issues, we investigated the genetic structure of the legume pod borer, Maruca vitrata, which is a sub-tropical pest species that causes severe damage to legume crops in Hawaii and the U.S. territory of Puerto Rico. We show that two distinct species of legume pod borer are present in sub-tropical regions and inhabit different geographic regions of the world. These results may impact the scientific recommendations regarding management of resistance of this insect when cowpea expressing insecticidal toxins from Bacillus thuringiensis (Bt) are released for commercial use. This information will be useful to scientists interested in using Bt crops to control insect pests, especially in the tropics.
Technical Abstract: Maruca vitrata Fabricius is a pantropical lepidopteran pest of legumes. Phylogenetic analysis of a mitochondrial cytochrome c oxidase-I gene (coxI) fragment indicates that three Maruca sp. mitochondrial lineages have unique geographic distributions [lineages 1 and 2: Australia, Taiwan, and West Africa (Niger, Nigeria, and Burkina Faso), and lineage 3: Puerto Rico]. The haplotype (C30, C114) is specific to lineage-1 and was assayed by NsiI and SacI polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) within population samples; it was not observed in the Puerto Rican samples, but was nearly fixed among samples from West Africa, Australia, and Taiwan (85.5 to 100%). Re-sequencing and phylogenetic analyses of PCR-RFLP defined cox1 haplotypes indicate that nucleotide diversity is highest among samples from West Africa. Phylogenetic reconstruction based upon ribosomal DNA (rDNA) internal transcribed spacer-2 (ITS-2) sequences provided additional evidence for three Maruca sp. clades. These data suggest that multiple unique Maruca species or subspecies are present worldwide, which has implications for the management of this pest species-complex. This information will be useful to scientists interested in using Bacillus thuringiensis (Bt) crops to control insect pests, especially in the tropics.