Distribution of Hoplolaimus Species in Soybean Fields in South Carolina and North Carolina.

Hoplolaimus columbus is an important nematode pest of soybean in South Carolina and North Carolina. Tolerant cultivars are available for the management of this plant-parasitic nematode; however, variation in the response of soybean cultivars to H. columbus populations has been observed. This variation may be due to the presence of different species or high genetic diversity of H. columbus populations. The objective of this study was to identify the Hoplolaimus spp. present in fields representing the main soybean-growing regions in South Carolina and North Carolina and to examine the genetic variability of these populations. In South Carolina, the only species found associated with soybean was H. columbus but, in North Carolina, H. stephanus was the dominant species. The two species were never found together. Genetic variability analyses of a mitochondrial and a nuclear marker showed that only one haplotype was shared by the H. columbus populations. H. stephanus showed higher genetic variability, with private haplotypes per sampling location. Knowledge of the distribution and genetic variability of these two Hoplolaimus spp. is valuable to growers to determine potentially damaging infestations of these plant-parasitic nematodes in soybean fields.