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- Stutz, Rebecca S., et al.
(författare)
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A mechanistic understanding of repellent function against mammalian herbivores
- 2019
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Ingår i: Ecological processes. - : Springer Science and Business Media LLC. - 2192-1709. ; 8
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Tidskriftsartikel (refereegranskat)abstract
- Background: Browsing repellents are widely used to deter large herbivores from consuming plants of ecological,economic and aesthetic importance. Understanding how these repellents function on a behavioural mechanisticlevel is critical to predicting effectiveness. Here, we illustrate how these mechanisms can be tested, by exposing amodel mammalian herbivore, the fallow deer, to different concentrations of a commercial chemical repellent(HaTe2) in two-choice feeding trials.Results:The repellent acted as a defensive chemical for the food by both reducing visitation and the amountconsumed. Deer favoured the less defended feeders before ingesting any food, suggesting that the repellentaltered olfactory and/or visual cues. Deer also consumed less of the more defended food when choosing betweenlow and high repellent feeders than no and low repellent feeders, indicating that the repellent modified flavourand/or sensation. Repellent effectiveness declined with increased exposure, suggesting that consumption had nonegative post-ingestive effects, and thus, deterrence was not caused by a conditioned aversion or irritation. Instead,this pattern suggests that deer learned, through repeated sampling of repellent-treated food, that there was noadverse physiological effect of ingesting it.Conclusions:These results imply that HaTe2 repellent will not be effective over prolonged periods or in theabsence of alternative untreated food. Understanding the mechanisms driving repellent function using two-choicetrials could help practitioners decide whether a particular repellent is likely to be effective against mammalianherbivory in their management scenario.
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- Stutz, Rebecca S., et al.
(författare)
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Efficient application of a browsing repellent : Can associational effects within and between plants be exploited?
- 2019
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Ingår i: European Journal of Forest Research. - : Springer Science and Business Media LLC. - 1612-4669 .- 1612-4677. ; 138:2, s. 253-262
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Tidskriftsartikel (refereegranskat)abstract
- Browsing can reduce forest productivity, particularly when the apical shoots of trees are damaged. Repellents are used widely to reduce browsing, but application is costly. To improve efficiency, it may be possible to take advantage of associational plant refuge effects, requiring repellents to be applied only to some trees or parts of trees, or reapplied less frequently. Using captive moose (Alces alces) and constructed stands of Scots pine (Pinus sylvestris), we tested for potential refuges by applying a commercial repellent (HaTe2) to all, alternate or none of the apical shoots, or all of the previous-year apical shoots. We also tested for potential refuges under field conditions, applying the repellent to all, alternate or none of the apical pine shoots in forest stands. Captive moose (two individuals in a 2.1-ha enclosure, similar to 95 individuals km(-2)) browsed 100% of trees, but were significantly less likely to browse apical shoots treated with repellent. Associational refuge was ineffective both within and between trees. In the field (0.84 moose km(-2)), only 1.3% of trees sustained browsing damage. Applying the repellent to the apical shoots of pines had no direct repellent effect nor any within-plant associational effects. Trees with treated apical shoots provided some protection for untreated neighbouring trees, but this was not biologically meaningful given the low percentage of trees browsed overall. Here, a simple captive experiment was not predictive of the browsing response observed in the field, demonstrating the need to test repellent application strategies in situ.
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