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Contrasting patterns of herbivore and predator pressure on invasive and native plants

Engelkes, T. and Wouters, B. and Bezemer, T.M. and Harvey, J.A. and Van der Putten, W.H. (2012) Contrasting patterns of herbivore and predator pressure on invasive and native plants. Basic and Applied Ecology, 13, 725-734. ISSN 1439-1791.

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Official URL: http://dx.doi.org/10.1016/j.baae.2012.10.005

Abstract

Invasive non-nativeplant species often harbor fewer herbivorous insects than related nativeplant species. However, little is known about how herbivorous insects on non-nativeplants are exposed to carnivorous insects, and even less is known on plants that have recently expanded their ranges within continents due to climate warming. In this study we examine the herbivore load (herbivore biomass per plant biomass), predator load (predator biomass per plant biomass) and predatorpressure (predator biomass per herbivore biomass) on an inter-continental non-native and an intra-continental range-expanding plant species and two congeneric native species. All four plant species co-occur in riparian habitat in north-western Europe. Insects were collected in early, mid and late summer from three populations of all four species. Before counting and weighing the insects were classified to trophic guild as carnivores (predators), herbivores, and transients. Herbivores were further subdivided into leaf-miners, sap-feeders, chewers and gallers. Total herbivore loads were smaller on inter-continental non-native and intra-continental range-expanding plants than on the congeneric natives. However, the differences depended on time within growing season, as well as on the feeding guild of the herbivore. Although the predator load on non-nativeplants was not larger than on natives, both non-nativeplant species had greater predatorpressure on the herbivores than the natives. We conclude that both these non-nativeplant species have better bottom-up as well as top-down control of herbivores, but that effects depend on time within growing season and (for the herbivore load) on herbivore feeding guild. Therefore, when evaluating insects on non-nativeplants, variation within season and differences among feeding guilds need to be taken into account.

Item Type:Article
Institutes:Nederlands Instituut voor Ecologie (NIOO)
ID Code:12836
Deposited On:29 Oct 2012 01:00
Last Modified:28 Mar 2013 14:40

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