Regional-scale impact of the weed biocontrol agent Mecinus janthinus on Dalmatian toadflax (Linaria dalmatica)

Hezewijk, Brian H. Van; Bourchier, Robert S.; Clerck-Floate, Rosemarie De

doi:10.1016/j.biocontrol.2010.08.008

Cited by 26 publications

(16 citation statements)

References 20 publications

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“…These limitations can be overcome to some extent by manual distribution of agents once they have locally established and engaged in population growth. Indeed this strategy is used commonly in biological control to increase spread rates even for species that are able to spread on their own (e.g., Drea and Hendrickson 1986;Caltagirone and Doutt 1989;Ireson and Webb 1996;Pratt et al 2003;van Hezewijk et al 2010). Such redistribution can be very effective in countering low dispersal rates or for overcoming substantial geographic barriers (e.g., expanses of ocean between islands), and it can also occur unintentionally (Petit et al 2009).…”

Section: Too Little Dispersalmentioning

confidence: 96%

A ‘Goldilocks’ hypothesis for dispersal of biological control agents

Heimpel

Asplen

2011

BioControl

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The rate at which biological control agents disperse from release sites has important implications for their establishment and spread. Low rates of dispersal can yield spread that is too slow and may necessitate redistribution efforts for importation biological control and a high density of release sites for augmentation. Low dispersal rates may also lead to inbreeding at the site of release. On the other hand, high rates of dispersal can lead to Allee effects at the leading edge of the invasion front, potentially reducing the likelihood of establishment. Given these disadvantages associated with both low and high dispersal rates, we argue that intermediate rates of dispersal are likely to maximize the probability of establishment and appropriate spread for biological control agents released in the context of either importation or augmentative biological control. We consider this putative relationship a 'Goldilocks hypothesis' since it posits an optimum at intermediate values. In this review paper we begin by discussing the rationale for the Goldilocks hypothesis and then provide a case study from our work on importation biological control of the soybean aphid, Aphis glycines. Work on the soybean aphid parasitoid Binodoxys communis has shown that long-distance dispersal of immature parasitoids within winged migrating aphids is unlikely. This is likely good news for importation biological control because parasitoids dispersed in this manner would likely encounter crippling Allee effects. On the other hand, results from a field release study also suggest that female B. communis females (but not males) disperse actively from release sites. This female-biased dispersal may lead to strong mate-finding Allee effects and therefore may make establishment less likely.

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Section: Too Little Dispersalmentioning

confidence: 96%

A ‘Goldilocks’ hypothesis for dispersal of biological control agents

Heimpel

Asplen

2011

BioControl

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“…Declines in ramet and patch density in the field have been associated with the release of M. janthiniformis (De Clerck‐Floate & Miller ; Sing et al . ; Van Hezewijk, Bourchier & De Clerck‐Floate ), whose adult and larval feeding can reduce shoot height and decrease reproduction of L. dalmatica (Schat et al . ; Goulet et al .…”

Section: Introductionmentioning

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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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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“…Other studies have demonstrated negative effects of M. janthinus larvae on plant physiology(Peterson et al 2005) as well as the negative effects of increased weevil densities within stems on plant size(Van Hezewijk et al 2010). Accordingly, the number of oviposition scars per cm can provide a good estimate of plant injury caused by this specialist herbivore.Among the field sites under investigation, only Lefthand Canyon had detailed information on the history of the release of M. janthinus, which included location and date of release as well as the number of individuals released.…”

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confidence: 99%

Soil nitrogen availability and herbivore attack influence the chemical defenses of an invasive plant (Linaria dalmatica; Plantaginaceae)

Jamieson

Bowers

2011

Chemoecology

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Chemical defenses are thought to contribute to the invasion success and impacts of many introduced plants; however, for most of these species, little is known about these compounds and how they vary in natural environments. Plant allelochemical concentrations may be affected by a variety of abiotic and biotic factors, including soil nutrients and herbivores. Moreover, such quantitative variation is likely to play an important role in species interactions involving these invasive plants. The purpose of this study was to examine patterns of variation in iridoid glycoside concentrations of the invasive plant Linaria dalmatica (Plantaginaceae). We conducted a greenhouse experiment to investigate the effect of soil nitrogen availability on iridoid glycoside concentrations. Results from this experiment showed that plant iridoid glycoside concentrations decreased with increased nitrogen availability. Additionally, plants were collected from multiple field sites in order to characterize the influence of population, soil nitrogen availability, and herbivore attack on iridoid glycoside variation. Results from field studies indicated that plants demonstrated considerable seasonal variation, as well as variation within and among populations, with iridoid glycoside concentrations ranging from approximately 1 to 15% dry weight. The relationship between soil nitrogen and plant iridoid glycosides varied among populations, with a strong negative correlation in one population, a marginally significant negative relationship in a second population, and no relationship in the remaining two populations. Additionally, we found a negative relationship between iridoid glycoside concentrations and plant injury by an introduced biocontrol agent, the stem-mining weevil Mecinus janthinus (Cucurlionidae). These results show that plant allelochemical concentrations can vary widely in natural environments and suggest that levels of plant defense may be reduced by increased soil nitrogen availability and herbivore attack in this invasive plant species.

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Regional-scale impact of the weed biocontrol agent Mecinus janthinus on Dalmatian toadflax (Linaria dalmatica)

Cited by 26 publications

References 20 publications

A ‘Goldilocks’ hypothesis for dispersal of biological control agents

A ‘Goldilocks’ hypothesis for dispersal of biological control agents

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

Soil nitrogen availability and herbivore attack influence the chemical defenses of an invasive plant (Linaria dalmatica; Plantaginaceae)

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