Potential Use of DNA Barcodes in Regulatory Science: Identification of FDA's “The Dirty 22”

Introduction: The Food, Drug, and Cosmetic Act (FD&C Act) prohibits the distribution of food that is adulterated, and the regulatory mission of the U.S. Food and Drug Administration (FDA) is to enforce this Act. FDA field labs have identified the 22 most common pests that contribute to the spread of foodborne disease. The current method of detecting filth and extraneous material (tail, leg, carcass, etc.) is done visually using microscopy. Because microscopy can be time consuming and may yield inaccurate/non-specific identifications due to the expertise needed, an alternate molecular method is needed.

Purpose: To sequence DNA from the 5’ region of cytochrome oxidase I (COI) (DNA Barcode) of 22 of the most common pests (“The Dirty 22”) contributing to the spread of foodborne pathogens. The targeted pests are: German cockroach, Brownbanded cockroach, Oriental cockroach, American cockroach, Pharaoh ant, Thief ant, House fly, Stable fly, Little house fly, Latrine fly, Cosmopolitan blue bottle fly, Holarctic blue bottle fly, Oriental latrine fly, Secondary screwworm, Blue bottle fly, Green bottle fly, Black blow fly, Redtailed flesh fly, House mouse, Polynesian rat, Norway rat and Roof rat.

Methods: Genomic DNA of the targeted 22 species was extracted and the barcode region of the COI gene was amplified and sequenced.

Results: DNA barcodes were generated for all 22 species.

Significance: Our study demonstrates that DNA barcoding can be a powerful tool for species identification and has broad regulatory applications. To date, this is the first molecular assay to attempt and successfully identify DNA barcodes for the FDA-targeted 22 species.  The results from this study have the potential to aid the U.S. Food and Drug Administration’s initiative to provide protection and safety to the food and animal feed.