Submitted to: Annals of the Entomological Society of America
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/18/2001
Publication Date: 11/1/2001
Citation: Roehrdanz, R.L. 2001. Genetic differentiation of southeastern boll weevil and thurberia weevil populations of Anthonomus grandis (Coleoptera: Curculionidae) using mitochondrial DNA. Annals of the Entomological Society of America. 94(6):928-935. Interpretive Summary: RFLP differences between boll weevils and thurberia weevils were observed. Restriction fragment length polymorphisms of PCR-amplified mtDNA revealed several patterns with distinct differences between thurberia weevils from the Arizona mountains and boll weevils from cotton growing regions to the east of Arizona. These diagnostics should help categorize any weevils that might appear in Arizona cotton and assist decision making for the appropriate response. Additional geographic collections of boll weevils need to be examined to determine if other geographic populations of boll weevils are equally different from the thurberia weevil. If the differentiation persists, the procedure can be used to inform growers and action agencies whether any newly discovered weevils in an eradicated area are cause for concern.
Technical Abstract: The southeastern boll weevil (SBW) and the thurberia boll weevil (TW) are considered to be morphologically similar but behaviorally different variants of the same species, Anthonomus grandis Boheman. PCR was used to amplify a 9.2 kb section of the mitochondrial genome and the resulting amplicon was cleaved with restriction enzymes. RFLPs of SBW from four cotton growing locations in Texas and one in northeastern Mexico were compared with TW from three sites in Arizona. Six haplotypes were recognized from the SBW and 12 haplotypes were found among the TW. There were no shared haplotypes between these two groups. Polymorphism was observed within the two weevil types. The three TW locations exhibit some geographic isolation and exhibit differences in both the haplotypes present and the relative frequencies of the haplotypes. Only one of the haplotypes was recovered at all three of the Arizona sites. The SBW samples showed less variability with the northern most site having the lowest polymorphism. Two haplotypes were shared by all four SBW populations and comprised 72% of the insects examined. The range of genetic distances between haplotypes was <0.001-0.022. A third boll weevil variant, the Mexican boll weevil, was not explicitly examined. However 2 individuals were discovered that appear to represent a genetically distinct third population. The results describe apparent diagnostic restriction fragment differences between the TW and the SBW that could be used to help determine whether any future weevils found in Arizona or California cotton are TW, SBW or another population of weevils.