Table 2.

All observed SNP combinations producing six resistance multi-locus genotypes (MLGs) observed in our study

MLG	C190A	T170C	T2134A	U.S.	Mexico	Lab
1	RR	SS	SS	Yes	Yes	Yes
2	RS	RS	SS	Yes	No	No
3	RS	SS	RS	Yes	Yes	Yes
4	SS	RR	SS	Yes	No	No
5	SS	SS	RR	No	Yes	Yes
6	SS	RS	RS	No	Yes	No

Each MLG has two (and only two) resistance SNPs. Specific MLGs were associated with each sampling source, although MLGs 1 and 3 were found in all three sources. Multi-locus genotype 1 was geographically widespread and the single most common MLG in our study.