Geographic population genetic structure of the New World screwworm, Cochliomyia hominivorax (Diptera: Calliphoridae), using SNPs

Authors: Tietjen, Mackenzie; Perez De Leon, Adalberto - Beto; SAGEL, AGUSTIN - US Department Of State; SKODA, STEVE - Retired ARS Employee; PHILLIPS, PAMELA - Animal And Plant Health Inspection Service (APHIS); MITCHELL III, ROBERT - Environmental Protection Agency (EPA); DURAN, UZIEL - Animal And Plant Health Inspection Service (APHIS); TORTOSA, SILVIA - Animal And Plant Health Inspection Service (APHIS); Arp, Alex

Submitted to: Journal of Medical Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/3/2022
Publication Date: 3/22/2022
Citation: Tietjen, M., Perez De Leon, A.A., Sagel, A., Skoda, S.R., Phillips, P.L., Mitchell III, R.D., Duran, U., Tortosa, S., Arp, A.P. 2022. Geographic population genetic structure of the New World screwworm, Cochliomyia hominivorax (Diptera: Calliphoridae), using SNPs. Journal of Medical Entomology. 59(3):874-882. https://doi.org/10.1093/jme/tjac024.
DOI: https://doi.org/10.1093/jme/tjac024

Interpretive Summary: There have been outbreaks of the livestock parasite, the New World screwworm in previously eradicated locations. A reference database using genetics was developed to identify the origin of these outbreaks. Knowing the origin of outbreaks will help in mitigating future outbreaks.

Technical Abstract: The New World screwworm, Cochliomyia hominivorax (Coquerel 1858) (Diptera: Calliphoridae), is a serious parasite of livestock, humans, and other warm-blooded animals. It has been eradicated from the northern parts of its historical range down to the Panama - Colombian border where a permanent barrier zone is maintained. This eradication was accomplished through using the sterile insect technique (SIT). In 2016 there was an outbreak of C. hominivorax in the Florida Keys. In only six months, this pest was successfully re-eradicated using SIT, but the geographic origin of the invasion has yet to be resolved. It was previously determined that the Florida flies most likely represented a single invasion, and it was recommended that a finer-scale genetic assessment should be completed. Thus, this study aimed to identify the origin of the outbreak and develop a population genetic database to reference future outbreaks. This was accomplished by sequencing samples originating from 12 sources using a genotyping by sequencing (GBS) approach to obtain single nucleotide polymorphisms (SNPs). Geographic population structuring was identified for ten populations that clustered according to geographic location. It was determined that the Florida outbreak samples most closely resembled samples from the outer Caribbean cluster which included samples from Dominican Republic and Trinidad and Tobago.