van Nouhuys, S and Harris, DC and Hajek, AE (2023) Population level interactions between an invasive woodwasp, an invasive nematode and a community of native parasitoids. In: NeoBiota, 82 . pp. 67-88.
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Abstract
Parasitic nematodes and hymenopteran parasitoids have been introduced and used extensively to control invasive Eurasian Sirex noctilio woodwasps in pine plantations in the Southern Hemisphere where no members of this community are native. Sirex noctilio has more recently invaded North America where Sirexassociated communities are native. Sirex noctilio and its parasitic nematode, Deladenus siricidicola, plus six native hymenopteran woodwasp parasitoids in New York and Pennsylvania, were sampled from 204 pines in 2011–2019. Sirex noctilio had become the most common woodwasp in this region and the native parasitoids associated with the native woodwasps had expanded their host ranges to use this invader. We investigated the distributions of these species among occupied trees and the interactions between S. noctilio and natural enemies as well as among the natural enemies. Sirex noctilio were strongly aggregated, with a few of the occupied trees hosting hundreds of woodwasps. Nematode parasitism was positively associated with S. noctilio density, and negatively associated with the density of rhyssine parasitoids. Parasitism by the parasitoid Ibalia leucospoides was positively associated with host (S. noctilio) density, while parasitism by the rhyssine parasitoids was negatively associated with density of S. noctilio. Thus, most S. noctilio come from a few attacked trees in a forest, and S. noctilio from those high-density trees experienced high parasitism by both the invasive nematode and the most abundant native parasitoid, I. l. ensiger. There is little evidence for direct competition between the nematodes and parasitoids. The negative association occurring between rhyssine parasitoids and I. l. ensiger suggests rhyssines may suffer from competition with I. l. ensiger which parasitize the host at an earlier life stage. In addition to direct competition with the native woodwasp Sirex nigricornis for suitable larval habitat within weakened trees, the large S. noctilio population increases the parasitoid and nematode populations, which may increase parasitism of S. nigricornis. © Saskya van Nouhuys et al. This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
| Item Type: | Journal Article |
|---|---|
| Publication: | NeoBiota |
| Publisher: | Pensoft Publishers |
| Additional Information: | The copyright for this article belongs to the Authors. |
| Keywords: | Aggregation; co-infection; competition; Deladenus; density dependence; forest pest; Ibalia; parasite community; pine; Rhyssa; Sirex noctilio; spillback |
| Department/Centre: | Division of Biological Sciences > Centre for Ecological Sciences |
| Date Deposited: | 28 Mar 2023 08:46 |
| Last Modified: | 28 Mar 2023 08:46 |
| URI: | https://eprints.iisc.ac.in/id/eprint/81189 |
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