Invasive Species Compendium

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Abstract

Siricid parasitoids (Hymenoptera: Ichneumonidae) from eastern white pine and associated pine species in Southern Appalachia.

Abstract

This paper documents the occurrence of the following siricid parasitoids in the southern Appalachian Mountains: Megarhyssa nortoni in eastern white pine (Pinus strobus); Rhyssa howdenorum in eastern white pine, Virginia pine (Pinus virginiana), and shortleaf pine (Pinus echinata); and Rhyssa lineolata in Virginia pine. Furthermore, it documents the cleptoparasitoid species Pseudorhyssa nigricornis in eastern white pine and Virginia pine. The low number of siricid parasitoids is likely a consequence of low numbers of Sirex nigricornis as suggested by the low number of infested log stacks and a highly male-biased sex ratio in emerged adults of this haplo-diploid species. However, the presence of the cleptoparasite Pseudorhyssa nigricornis likely indicates significant numbers of siricid parasitoids over a broader landscape level. The abundance of the cerambycid R. inquisitor emerging from stacks might suggest competition for woodwasps infesting pine logs. These observations provide useful baseline information regarding host associations of native pine siricids, their parasitoids, and potential resource competitors in the southern Appalachian Mountains, should the invasive Sirex noctilio eventually become established in this region.