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Direct and indirect effects of egg parasitism by Neopolycystus Girault sp. (Hymenoptera: Pteromalidae) on Paropsis atomaria Olivier (Coleoptera: Chrysomelidae).

Duffy, M.P. and Nahrung, H.F. and Lawson, S.A. and Clarke, A.R. (2008) Direct and indirect effects of egg parasitism by Neopolycystus Girault sp. (Hymenoptera: Pteromalidae) on Paropsis atomaria Olivier (Coleoptera: Chrysomelidae). Australian Journal of Entomology, 47 (3). pp. 195-202.

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Article Link(s): http://dx.doi.org/10.1111/j.1440-6055.2008.00657.x

Publisher URL: http://www3.interscience.wiley.com/cgi-bin/home

Abstract

Neopolycystus sp. is the only primary egg parasitoid associated with the pest beetle Paropsis atomaria in subtropical eucalypt plantations, but its impact on its host populations is unknown. The simplified ecosystem represented by the plantation habitat, lack of interspecific competition for host and parasitoid, and the multivoltinism of the host population makes this an ideal system for quantifying the direct and indirect effects of egg parasitism, and hence, effects on host population dynamics. Within-, between- and overall-egg-batch parasitism rates were determined at three field sites over two field seasons, and up to seven host generations. The effect of exposure time (egg batch age), host density proximity to native forest and water sources on egg parasitism rates was also tested. Neopolycystus sp. exerts a significant influence on P. atomaria populations in Eucalyptus cloeziana. plantations in south-eastern Queensland, causing the direct (13%) and indirect (15%) mortality of almost one-third of all eggs in the field. Across seasons and generations, 45% of egg batches were parasitised, with a within-batch parasitism rate of around 30%. Between-batch parasitism increased up to 5-6 days after oviposition in the field, although within-batch parasitism rates generally did not. However, there were few apparent patterns to egg parasitism, with rates often varying significantly between sites and seasons.

Item Type:Article
Additional Information:© The State of Queensland through its Department of Primary Industries and Fisheries. © Australian Entomological Society. © Blackwell Publishing Ltd.
Keywords:Eucalypt; parasitoid; paropsine.
Subjects:Science > Zoology > Invertebrates > Insects
Forestry > Sylviculture
Plant pests and diseases > Individual or types of plants or trees
Plant pests and diseases > Pest control and treatment of diseases. Plant protection > Organic plant protection. Biological control
Deposited On:03 Feb 2009 02:11
Last Modified:18 Apr 2011 01:38

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