Development of a DNA isolation method and microsatellites from the sweetpotato weevil (Cylas formicarius elegantulus) and characterization of genetic diversity

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

Submitted to: National Sweetpotato Collaborators Group Annual Meeting
Publication Type: Abstract Only
Publication Acceptance Date: 12/5/2019
Publication Date: N/A
Citation: N/A

Interpretive Summary:

Technical Abstract: The sweetpotato weevil is a serious insect pest of sweetpotato in the field and during storage and occurs in over 50 countries. Molecular techniques developed over the past two decades have revolutionized studies on insects. Logistics of sample collection is a limiting factor for studies of natural populations, particularly where preservation and recovery of nucleic acids are critical. This can pose challenges when dealing with insects because they are often small, cryptic, and difficult to capture. In addition, either live material is often unavailable, or they may be severe agricultural pests that have been quarantined with restricted movement of living specimens. Genomic DNA can be isolated readily from samples frozen and stored at -80°C, preserved in ethanol, or dried in silica gel. However, these preservation methods may not be practical when insects are collected under field conditions because trapping is generally a passive technique that requires unattended sampling periods during which samples may be subjected to environmental factors that could degrade the DNA. We developed a protocol for isolation of high-quality DNA from sweetpotato weevils collected from pheromone-baited aerial funnel traps. This study was based on our discovery that a two-week collection interval of sweetpotato weevils from pheromone traps did not permit isolation of intact high-quality genomic DNA. Information is lacking regarding the genetic diversity and population structure of the sweetpotato weevil within the U.S. To conduct population genetics analyses on sweetpotato weevils collected from three populations (Hawaii, Georgia, and South Carolina) in the U.S., microsatellites were developed from publicly available sweetpotato weevil transcriptome sequences. Characterization of the microsatellites demonstrated conclusively that diversity in three populations of sweetpotato weevil is low, which is consistent for an introduced pest. Knowledge of the population structure and genetic diversity of the sweetpotato weevil is critical information for developing durable host resistance, and we have demonstrated the suitability of the microsatellite loci for conducting range-wide population studies for this important sweetpotato pest.