Evaluating the effects of native nematode species of the genus Deladenus (Thorne 1941) on the woodwasp Sirex nigricornis F. (Hymenoptera: Siricidae) from Illinois and Louisiana

Evaluating the effects of a native nematode species of the genus Deladenus (Thorne 1941) on the woodwasp Sirex nigricornis F. (Hymenoptera: Siricidae) from southern Illinois and Louisiana.  ELLIOTT ZIEMAN, JOHN REEVE and F. AGUSTIN JIMÉNEZ, Department of Zoology, Southern Illinois University Carbondale, Carbondale, IL 62901.

Woodwasps (Hymenoptera: Siricidae) produce phloem eating larvae. Native Sirex woodwasps cause little damage to pine trees in their natural ranges. The European woodwasp Sirex noctilio F. (Hymenoptera: Siricidae) has caused severe damage in areas of the Southern Hemisphere where it has been accidentally introduced into pine plantations. In 2004 Sirex noctilio was discovered in Syracuse, NY. In the Southern Hemisphere some strains of the nematode Deladenus (=Beddingia) siricidicola (Bedding 1964) have been used as a biological control agent because they are able to castrate woodwasps. Deladenus siricidicola has been found infecting S. noctilio in Ontario, Canada but in all cases the nematodes did not penetrate the eggs which is the primary mechanism of control. In this study, we examined the effects of native Deladenus nematodes on the native woodwasp S. nigricornis. These nematodes had a prevalence of 30% in southern Illinois and in all but one wasp the nematodes penetrated the eggs. In this study we will determine what species of Deladenus is present in our study sites using morphological and genetic analysis. The nematodes from both southern Illinois and Louisiana had identical DNA sequences of Cytochrome Oxydase 1 (CO1), indicating they are likely the same species. Further comparisons are needed to determine how closely the morphometric features match previously described species of Deladenus.