The spatial genetic differentiation of the legume pod borer, Maruca vitrata F. (Lepidoptera: Crambidae) populations in West Africa
Tolulope A. Agunbiade; Brad S. Coates; Kyung S. Kim; David Forgacs; Venu M. Margam; Larry L. Murdock; Malick N. Ba; Clementine L. Binso-Dabire; Ibrahim Baoua; Mohammad F. Ishiyaku; Tamo Manuele; Barry R. Pittendrigh
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A poster presented at the 2012 Global Pulse Researchers Meeting, Kigali, Rwanda- “Transforming Grain-Legume Systems to Enhance Nutrition and Livelihoods”. Abstract: The legume pod borer, Maruca vitrata, is an endemic insect pest that causes significant yield loss to the cowpea crop in West Africa, and contributes to food shortages and malnutrition in native human populations. The genetic structure of M. vitrata was investigated at five sites from Burkina Faso, Niger and Nigeria using microsatellite markers. Polymorphisms found ranged from 1 (marker 3393) to 8 (marker 32008) alleles per locus, and observed heterozygosity was from 0.0 to 0.8. Three of the loci deviated significantly from Hardy-Weinberg Equilibrium (HWE) in specimens from Nigeria and Burkina Faso, whereas no loci deviated significantly in Niger. Analysis of molecular variance (AMOVA) indicated that 67.4% level of the genetic variation was within individuals compared to 17.3% among populations. A global estimate of FST = 0.1 (ENA corrected FST = 0.1) was significant (P ? 0.05) and corroborated by pairwise FST values that were significant among all possible comparisons. A significant correlation was found between genetic divergence and geographic distance between subpopulations (R2 = 0.6, P = 0.01), and cluster analysis by the program STRUCTURE suggested that co-ancestry of genotypes were indicative of three distinct populations. The spatial genetic variance among M. vitrata in West Africa may be due to limited gene flow, north-south seasonal movement pattern or other reproductive barriers. This information is important for the cultural, chemical, and biological control strategies for managing M. vitrata.