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Predator refuges for conservation biological control in an intermediately disturbed system: the rise and fall of a simple solution

Liman, Anna-Sara and Eklund, Karin and Björkman, Christer (2016). Predator refuges for conservation biological control in an intermediately disturbed system: the rise and fall of a simple solution. Journal of applied ecology. 53:6, 1823-1830
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Official URL: http://onlinelibrary.wiley.com/doi/10.1111/1365-26...

Abstract

1. Managed systems harvested at intermediate time-scales have advantages over annual short-cycled systems in maintaining top-down control of insect herbivores, and the flexible harvest regimes in these systems provide opportunities for habitat management that can stabilize predator-prey population dynamics across harvests - resulting in reduced risk of pest outbreaks.
2. In a large-scale field experiment, we explored whether retaining refuges, that is preserving parts of the stand to reduce predator mortality, could reduce the risk of pest insect outbreaks in willow short-rotation coppice. Population densities of three omnivorous predator species and three outbreaking herbivorous leaf beetle species were monitored over four years aftercoppice (stem harvest) in eight stands with refuges (treatment) and eight stands without refuges (control). Predation pressure was estimated in years three and four.
3. Contrary to our predictions, leaf beetle densities were higher in stands with refuges and predator densities were higher in stands without refuges. Leaf beetle egg mortality increased with total predator density, but did not differ between stands with and without refuges.
4. These unexpected results can be attributed to interactions between dispersal and patchage. The altered phenology of coppiced stems may have triggered leaf beetle aggregation in refuges and migration from stands without refuges. A behavioural response to resource concentration in retained old patches likely transformed the predator refuge from a ‘source' to a ‘sink'.
5. Synthesis and applications. This study shows that retaining refuges in willow short-rotation coppice to facilitate predator population recovery after harvest can come at the cost of more attractive herbivore habitats - and thus increased pest problems. We conclude that crop refuges in systems with intermediate disturbance regimes pose new challenges for conservation biological control, in particular the need to consider how patch age affects dispersal and recolonization of both pest and predators.

Authors/Creators:Liman, Anna-Sara and Eklund, Karin and Björkman, Christer
Title:Predator refuges for conservation biological control in an intermediately disturbed system: the rise and fall of a simple solution
Series/Journal:Journal of applied ecology (0021-8901)
Year of publishing :2016
Volume:53
Number:6
Page range:1823-1830
Number of Pages:8
Publisher:Springer
ISSN:0021-8901
Language:English
Publication Type:Journal article
Refereed:Yes
Article category:Scientific peer reviewed
Version:Published version
Full Text Status:Public
Subjects:(A) Swedish standard research categories 2011 > 1 Natural sciences > 106 Biological Sciences (Medical to be 3 and Agricultural to be 4) > Ecology
Agrovoc terms:pests of plants, biological control agents, predators, Salix
Keywords:conservation biological control, harvest, insect outbreak, omnivore, patch age, perennial crop, recolonization, refuge, short-rotation coppice
URN:NBN:urn:nbn:se:slu:epsilon-e-3840
Permanent URL:
http://urn.kb.se/resolve?urn=urn:nbn:se:slu:epsilon-e-3840
Additional ID:
Type of IDID
Web of Science (WoS)000387768800019
DOI10.1111/1365-2664.12709
ID Code:13904
Faculty:NJ - Fakulteten för naturresurser och jordbruksvetenskap
Department:(NL, NJ) > Dept. of Ecology
(S) > Dept. of Ecology
Deposited By: SLUpub Connector
Deposited On:20 Dec 2016 07:53
Metadata Last Modified:20 Dec 2016 07:53

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