Kdr allelic variation in a sodium channel gene from a population of South Carolina Heliothis virescens (Fabricius)

Mutations at V421M and L1029H in the hscp sodium channel gene are known to contribute to knockdown resistance (kdr) in the Woodrow, Dalzell, and PTJ strains of H. virescens (tobacco budworm) from the cotton fields of South Carolina, USA. In the IS6 region of the sodium channel gene, the frequencies of the mutant allele methionine in the Woodrow and Dalzell strains were 0.07 and 0.1, respectively. For the IIS6 region, the frequencies of the mutant allele histidine in Woodrow and Dalzell strains were 0.175 and 0.263, respectively. In the PTJ strain, the frequencies of methionine and histidine alleles were 0 and 0.1, respectively. The Hpy3 allele, which is strongly linked to the histidine mutant allele, was also found in Woodrow and Dalzell strains. In addition, we found a new allele, which is one nucleotide different from Hpy3, called Hpy3-1, and found that it is also linked to histidine.