Biological control and precipitation effects on spotted knapweed (<i>Centaurea stoebe</i>): empirical and modeling results

Maines, Anastasia P.; Knochel, David G.; Seastedt, Timothy R.

doi:10.1890/es13-00094.1

Cited by 17 publications

(19 citation statements)

References 45 publications

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“…Our model selection procedure, however, indicated that precipitation and herbivory do not interact at the landscape scalea result also consistent with biological control of spotted knapweed [Centaura stoebe L. subsp. micranthos (Gugler) Hayek] in Colorado USA (Maines, Knochel & Seastedt 2013). Other analyses have also revealed that precipitation does not indirectly affect landscape-scale population growth of M. janthiniformis (A.S. Weed, unpublished data).…”

Section: Discussionmentioning

confidence: 94%

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Density dependence, precipitation and biological control agent herbivory influence landscape‐scale dynamics of the invasive Eurasian plant Linaria dalmatica

Weed

Schwarzländer

2014

Journal of Applied Ecology

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Summary1. Resource availability and natural enemies are among the most commonly cited mechanisms affecting competitive ability of invasive plants, but their simultaneous effects on plant dynamics are seldom evaluated in the field. Understanding how endogenous and exogenous factors affect invasive plant abundance is essential when evaluating the impact of classical weed biological control agents because misinterpretations of the mechanisms regulating plant demography may bias inference of herbivore impact. 2. In this study, we report results from a citizen-science monitoring programme initiated to evaluate the effects of the stem-mining weevil Mecinus janthiniformis on the Eurasian invasive weed Dalmatian toadflax Linaria dalmatica. We used a discrete model of population dynamics to evaluate the relative importance of endogenous and exogenous processes affecting changes in ramet density of L. dalmatica at 38 spatially replicated sites in Idaho, USA. 3. Analysis of per-capita population growth rates based on ramet density indicated the presence of direct density dependence, which was most likely due to intraspecific competition. Changes in ramet density were not influenced by the abundance of the resident plant community. 4. Precipitation had a strong, positive effect on ramet density of L. dalmatica, while the abundance of M. janthiniformis had a weaker, but significant, negative effect after accounting for the density dependence. There was no support for an interactive effect between precipitation and herbivory. 5. Synthesis and applications. Our results indicate that biological control is an important factor affecting weed population growth at the landscape scale, but they also suggest that biological control impact may vary considerably on local infestations due to site-specific variation in rainfall and density-dependent processes. We recommend that invasive plant management strategies integrate precipitation and biological control agent monitoring into their programmes to estimate expected biological control efficacy. Alternative control methods should be prioritized in areas where herbivore impact is expected to be low.

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Section: Discussionmentioning

confidence: 94%

“…subsp. micranthos (Gugler) Hayek] in Colorado USA (Maines, Knochel & Seastedt ). Other analyses have also revealed that precipitation does not indirectly affect landscape‐scale population growth of M. janthiniformis (A.S. Weed, unpublished data).…”

Section: Discussionmentioning

confidence: 99%

Density dependence, precipitation and biological control agent herbivory influence landscape‐scale dynamics of the invasive Eurasian plant Linaria dalmatica

Weed

Schwarzländer

2014

Journal of Applied Ecology

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“…While many other studies find that invasive plants accumulate enemies in their invaded range (Liu & Stiling, ), it is rare that an exotic specialist enemy is present without purposeful introduction (but see Chang, Blakeslee, Miller, & Ruiz, ; Morrison & Hay, ; Stricker & Stiling, ). Typically, specialist herbivores, such as A. aurea , are introduced as biological control (DeWalt, ; Maines, Knochel, & Seastedt, ). In our study, a specialist herbivore does not significantly decrease population growth rate.…”

Section: Discussionmentioning

confidence: 99%

Role of multiple invasion mechanisms and their interaction in regulating the population dynamics of an exotic tree

Crandall

Knight

2017

Journal of Applied Ecology

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Understanding the mechanisms that allow exotic species to have rapid population growth is an important step in the process of controlling existing invasions and preventing future invasions. Several hypotheses have been proposed to explain why some exotic species become invasive, the most prominent of which focus on the roles of habitat disturbance, competitors and consumers. The magnitude and direction of each of these mechanisms on population dynamics observed in previous studies is quite variable. It is possible that some of this variation results from interactions between mechanisms. We examined all of these mechanisms and their interactions on the population dynamics of the Asian exotic tree Ailanthus altissima (Simaroubaceae) in fire‐suppressed oak‐hickory forests in Missouri, USA. We experimentally reduced herbivory (using insecticide), reduced interspecific competition (plant removals), and manipulated disturbance with prescribed fire. We projected the effects of these treatments and their interactions on population dynamics by parameterizing an integral projection model. The lowest population growth rate is found where fire is absent and biotic interactions are present. Fire increased population growth rate, likely through the suppression of interspecific competitors, since competitor removal treatments increased population growth rate in the absence but not presence of fire. These results indicate that biotic resistance from interspecific competitors, more so than consumers, is important for slowing the invasion of A. altissima. Furthermore, disturbances that weaken biotic interactions, such as fire, should be used with caution when restoring habitats invaded by A. altissima. Synthesis and applications. Examining the main and interactive effects of disturbance, competition and herbivory on the population dynamics of exotic species provides a comprehensive understanding of the role of these factors in the invasion process and provides guidance for exotic species management.

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“…Drought‐induced changes in herbivore performance and plant tolerance could have wide‐reaching implications for weed biological control. Drought could either increase or decrease the impacts of weed biological control agents; the combined effects of drought stress and herbivory on plant fitness could be stronger or weaker than would be expected from their individual impacts (Willis et al, 1993; Maines et al, 2013). For example, drought‐stressed Opuntia aurantiaca Lindl .…”

Section: Introductionmentioning

confidence: 99%

Combined effects of drought stress and psyllid herbivory on the invasive weed Scotch broom, Cytisus scoparius

Hogg

Moran

2020

Entomologia Exp Applicata

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Increases in the frequency and duration of droughts under global climate change could have implications for plant-insect interactions, and could either increase or decrease the effects of weed biological control agents. In this study, we used greenhouse and field experiments to examine the impacts of drought stress on the abundance and impacts of the adventive psyllid Arytainilla spartiophila Forster (Hemiptera: Psyllidae, Arytaininae) on its target weed Scotch broom, Cytisus scoparius (L.) Link (Fabaceae), in California, USA. The psyllid impacted plant growth in both field and greenhouse experiments, whereas drought stress affected plant growth in the greenhouse only, suggesting that other factors besides water availability may be more limiting for plants in the field. Effects on psyllid survival were consistent with the plant vigor hypothesis, which predicts that herbivores will perform better on vigorously growing plants; psyllid numbers were lower on drought-stressed plants in the greenhouse and were correlated with plant growth in both the greenhouse and the field. In the greenhouse, the combined effects of the psyllid and drought stress were additive, indicating that the effects of the psyllid were consistent across unstressed and drought-stressed plants. Although the psyllid is unlikely to control Scotch broom on its own, results suggest that it may work in conjunction with drought stress to suppress Scotch broom.

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Biological control and precipitation effects on spotted knapweed (Centaurea stoebe): empirical and modeling results

Cited by 17 publications

References 45 publications

Density dependence, precipitation and biological control agent herbivory influence landscape‐scale dynamics of the invasive Eurasian plant Linaria dalmatica

Density dependence, precipitation and biological control agent herbivory influence landscape‐scale dynamics of the invasive Eurasian plant Linaria dalmatica

Role of multiple invasion mechanisms and their interaction in regulating the population dynamics of an exotic tree

Combined effects of drought stress and psyllid herbivory on the invasive weed Scotch broom, Cytisus scoparius

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