Canadian Forest Service Publications

Nonlethal effects of nematode infection on Sirex noctilio and Sirex nigricornis (Hymenoptera siricidae). 2016. Haavik, L.J.; Allison, J.D.; MacQuarrie, C.J.K.; Nott, R.W.; Ryan, K; De Groot, P.; Turgeon, J.J. Environmental Entomology 45(2):320-327.

Year: 2016

Available from: Great Lakes Forestry Centre

Catalog ID: 37824

Language: English

CFS Availability: PDF (request by e-mail)

Available from the Journal's Web site.
DOI: 10.1093/ee/nvv223

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Abstract

A nonnative woodwasp, Sirex noctilio F., has established in pine forests in eastern North America. To facilitate prediction of the full range of impacts S. noctilio could have as it continues to spread in North American forest ecosystems, we studied the effects of infection by a nonsterilizing parasitic nematode on S. noctilio size, fecundity, and flight capacity and on the native woodwasp, S. nigricornis, size and fecundity. We also developed predictive models relating size to fecundity for both species. On average, S. noctilio (3.18 ± 0.05 mm) were larger than S. nigricornis (2.19 ± 0.04 mm). For wasps of similar size, S. nigricornis was more fecund. Nematode infection negatively affected potential fecundity by a mean difference of 36 and 49 eggs in S. noctilio and S. nigricornis, respectively. Nematode-infected males of S. noctilio, however, were larger than uninfected individuals. Nematode infection showed inconsistent results on mean speed and total distance flown by S. noctilio males and females. Nematode infection did not affect total distance flown by females, and so is unlikley to have a direct, or strong influence on S. noctilio flight capacity. Models developed to predict fecundity of Sirex spp. from body size, based on the close relationship between pronotum width and potential fecundity for both species (R(2) ≥ 0.69), had low measures of error when compared with true values of fecundity (± 25-26 eggs).

Plain Language Summary

A non-native woodwasp, Sirex noctilio has established in pine forests in eastern North America. To facilitate prediction of the full range of impacts S. noctilio could have as it continues to spread in North American forest ecosystems, we studied the effects of infection by a non-sterilizing parasitic nematode on S. noctilio size, fecundity, and flight capacity and on the native woodwasp, S. nigricornis size and fecundity. We also developed predictive models relating size to fecundity for both species. On average, S. noctilio were larger than S. nigricornis. For wasps of similar size, S. nigricornis were more fecund. Nematode infection negatively affected potential fecundity in S. noctilio and S. nigricornis. Nematode-infected males of S. noctilio, however, were larger than uninfected individuals. Nematode infection showed inconsistent results on mean speed and total distance flown by S. noctilio males and females. Nematode infection did not affect total distance flown by females, and so is unlikely to have a direct or strong influence on S. noctilio flight capacity. Models developed to predict fecundity of Sirex spp. from body size, based on the close relationship between thorax width and potential fecundity for both species had low measures of error when compared with true values of fecundity.

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