Development and characterization of microsatellites from the sweetpotato weevil, Cylas formicarius elegantulus

Authors: Wadl, Phillip; TRIGIANO, ROBERT - University Of Tennessee; BOGGESS, SARAH - University Of Tennessee; Harris-Shultz, Karen; Williams, Livy; McQuate, Grant

Submitted to: Journal of Applied Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/14/2020
Publication Date: 4/28/2020
Citation: Wadl, P.A., Trigiano, R.N., Boggess, S., Harris-Shultz, K.R., Williams III, L.H., Mcquate, G.T. 2020. Development and characterization of microsatellites from the sweetpotato weevil, Cylas formicarius elegantulus. Journal of Applied Entomology. 144(4):335-340. https://doi.org/10.1111/jen.12738.
DOI: https://doi.org/10.1111/jen.12738

Interpretive Summary: The sweetpotato weevil is a serious insect pest of sweetpotato in the field and storage and occurs in over 50 countries. Today, the sweetpotato weevil is found throughout the coastal plain of the U.S. southeastern states from North Carolina to Texas and in Hawaii and Puerto Rico. Information is lacking regarding the genetic diversity and population structure of the sweetpotato weevil within the U.S. Breeding for sweetpotato weevil resistance around the world has been ongoing for over 50 years, and while there have been resistant genotypes identified, there has been variability in the level of resistance across years and locations. It is unclear whether or not this variability is attributed to environmental effects, insect distribution or genetic differences, or true host resistance. This new knowledge of the genetic diversity and population structure of sweetpotato weevils can provide information for solving the genetic effect of the sweetpotato weevil on host resistance. This genetic information can also provide important insights for management strategies of this important pest, as knowledge of population structure can improve these strategies. Researchers at the USDA and the University of Tennessee developed molecular markers that were used to characterize population structure and genetic diversity within the sweetpotato weevil. Our study demonstrated conclusively that diversity in three populations of sweetpotato weevil is low, which is consistent for an introduced pest. Knowledge on the population structure and genetic diversity is critical information for developing durable host resistance. We have demonstrated the suitability of the microsatellite loci for conducting range-wide population studies for this important sweetpotato pest.

Technical Abstract: To conduct population genetics analyses on sweetpotato weevils (Cylas formicarius elegantulus) collected from three populations in the United States, microsatellite loci were developed from sweetpotato weevil (transcriptome sequences obtained from a publicly available database. Nineteen of 27 microsatellite loci tested were usable for population analysis. Sweetpotato weevil individuals from Georgia (N = 17), Hawaii (N = 16), and South Carolina (N = 12) were analyzed. Here, we present microsatellite primer sequences for 19 loci and population genetics statistics, including diversity, population differences, and relatedness. Thirty-nine alleles were detected in the 45 individuals and four private alleles were observed in individuals from the Hawaii and South Carolina populations. Observed heterozygosities ranged from 0.00 to 1.00 and expected heterozygosities ranged from 0.00 to 0.44, with all loci significantly deviating from Hardy-Weinberg expectations. The mean Shannon’s information index ranged from 0.30 to 0.49 for the three populations. Pairwise differences among populations (FST estimates) from individuals ranged from a low of 0.022 between Georgia and Hawaii, to a high of 0.036 between Georgia and South Carolina, and cluster analysis (PCA) indicated two populations independent of geographical location.