Molecular identification of Deladenus proximus Bedding, 1974 (Tylenchida: Neotylenchidae), a parasite of Sirex nigricornis (Hymenoptera: Siricidae)

Parasitic nematodes were isolated from Sirex nigricornis (Hymenoptera: Siricidae) females collected in baited traps across pine forests of Arkansas and Mississippi, USA. We examined 650-720 bp of cytochrome c oxidase subunit I and compared Arkansas and Mississippi sequences to sequences from nematodes collected in Illinois, Louisiana and New York that were positively identified as Deladenus proximus . We propose that a single species, D. proximus , occurs across Arkansas and Mississippi. Moreover, all sequences, which spanned a large geographic area (Louisiana to New York), exhibited only minor genetic variation (mean genetic distance of 0.004). This suggests that all examined specimens are a single species and could suggest continuous gene flow across eastern North America. Additional genes should be examined to discuss more fully the prospect of continuous gene flow.