Approximately 1,100 clones of a genomic EcoRl plasmid library of Meloidogyne arenaria were differentially screened with 32P-labeled genomic DNA from M. arenaria and M. incognito. One clone (pRIMAl7) hybridized preferentially to M. arenaria, and two clones (pRIMA2, pRIMA9) hybridized preferentially to M. arenaria and M. javanica. Restriction mapping and differential screening of pRIMAl7 revealed an internal 900-bp Seal fragment (pSCIMA 17) that was specific and produced a strong hybridization signal with DNA from M. arenaria only. Neighboring restriction fragments within pRIMAl7 were also species-specific but the hybridization signals were less strong. Fragments of pRIMAl7 hybridized to polymorphic interspersed repeats in M. arenaria populations;

however, not all fragments produced the same banding patterns. Sequence analysis showed that pSCIMAl7 contained a tandem repeat region of 28-bp subunitS repeated 19 times extending from the left border.

The tandem repeat was followed to the right by a region rich in A and T nucleotides. A dot blot method to identify root-knot nematode species with species-specific ONA probes using egg masses was developed. High

sensitivity as a result of internal tandem repeat sequences and hybridization to a high copy number interspersed repeat make pSCIMAl7 particularly suitable for diagnostic applications.