Review of approaches to evaluate the effectiveness of weed biological control agents

Morin, L.; Reid, Allen F.; Sims-Chilton, N.M.; Buckley, Yvonne M.; Dhileepan, K.; Hastwell, Graeme T.; Nordblom, Thomas L.; Raghu, S.

doi:10.1016/j.biocontrol.2009.05.017

Cited by 132 publications

(83 citation statements)

References 166 publications

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“…Interestingly, the leaf beetle Ophraella was also associated with lower seed densities produced (Table S10), which might be explained by lower A. artemisiifolia densities resulting from seedling mortality (Lommen et al, personal observations). This is promising from the perspective of biological control, but assessing the potential impact of this biological control agent requires data on the impact at the population level (Hahn et al 2012;Morin et al 2009). …”

Section: Discussionmentioning

confidence: 99%

Explaining variability in the production of seed and allergenic pollen by invasive Ambrosia artemisiifolia across Europe

et al. 2017

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To better manage invasive populations, it is vital to understand the environmental drivers underlying spatial variation in demographic performance of invasive individuals and populations. The invasive common ragweed, Ambrosia artemisiifolia, has severe adverse effects on agriculture and human health, due to its vast production of seeds and allergenic pollen. Here, we identify the scale and nature of environmental factors driving individual performance of A. artemisiifolia, and assess their relative importance. We studied 39 populations across the European continent, covering different climatic and habitat conditions. We found that plant size is the most important determinant in variation of per-capita seed and pollen production. Using plant volume as a measure of individual performance, we found that the local environment (i.e. the site) is far more influential for plant volume (explaining 25% of all spatial Published in "Biological Invasions doi: 10.1007/s10530-017-1640-9, 2018" which should be cited to refer to this work. variation) than geographic position (regional level; 8%) or the neighbouring vegetation (at the plot level; 4%). An overall model including environmental factors at all scales performed better (27%), including the weather (bigger plants in warm and wet conditions), soil type (smaller plants on soils with more sand), and highlighting the negative effects of altitude, neighbouring vegetation and bare soil. Pollen and seed densities varied more than 200-fold between sites, with highest estimates in Croatia, Romania and Hungary. Pollen densities were highest on arable fields, while highest seed densities were found along infrastructure, both significantly higher than on ruderal sites. We discuss implications of these findings for the spatial scale of management interventions against A. artemisiifolia.

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Section: Discussionmentioning

confidence: 99%

Explaining variability in the production of seed and allergenic pollen by invasive Ambrosia artemisiifolia across Europe

et al. 2017

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“…There are different approach options for the evaluation of the impact of a biocontrol agent (Blossey & Skinner 2000;Morin et al 2009). These approaches can involve manipulative experiments (in the laboratory, glasshouse and field) (Liu et al 2002), demographic modelling (Buckley et al 2004), and pre and post evaluation studies (van Klinken & Raghu 2006).…”

Section: Different Methods Of Evaluating the Impact Or Causality Of Bmentioning

confidence: 99%

Mimosa pigra dieback in the Northern Territory, Australia: Investigation into possible causes

Sacdalan¹

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In this study, Mimosa pigra dieback is described as plants or population of plants which appeared to suffer from ill health, death of their growing points and the emergence of green reshoots coming from the base. Dieback is an important phenomenon, not only in many crops and natural forests worldwide, but also in many invasive trees and shrubs in Australia. The dieback phenomenon is thought to be caused by complex and interacting factors and causes are often difficult to disentangle. In some cases it is a result of an interaction between both biotic and abiotic factors. Since 1988, dieback has been widely observed in Mimosa pigra L.(Fabaceae), a woody shrub that is one of the most serious exotic invaders of floodplains and riparian areas in the Top End of the Northern Territory. However, there has been no conclusive evidence of links between M. pigra dieback and specific causal factors. In addition, the dieback phenomenon has not been previously quantified.This thesis aimed to describe M. pigra dieback phenomenon at plant and population levels and its effect on plant growth, survival and demography. Specifically, the aim of this thesis was to evaluate the role of biotic factors (insect borers and fungal pathogens), and abiotic factors (soil pH and salinity), in relation to the development of M. pigra dieback. In addition, the thesis examines the pathogenicity of the fungal endophytes/pathogens associated with diebackaffected and healthy M. pigra. M. pigra has been a focus of biological control programs for more than 30 years, but it still remains a serious threat in the wetlands and conservation areas in the Top End of the Northern Territory. While extensive studies have been conducted to evaluate the impact of biological control programs, little is actually known about dieback and its causal factors.To evaluate the causal factors of M. pigra dieback, repeated ground surveys, plant health assessment and specimen collection of stems and soils, were conducted in the period 2011 to 2013 in established M. pigra sites on Melaleuca Station, Mary River, Northern Territory. Insect borers were quantified and putative fungal pathogen abundance were surveyed. A combined morphological and phylogenetic approach was used for fungal pathogens/endophyte identification. Using a subset of isolates, trials were performed to examine differences in the pathogenicity of the recovered fungal pathogens/endophytes.Results of field research showed that dieback in M. pigra is highly dynamic and fluctuates in its severity. Different sites showed increases and/or decreases in plant health over time.iii Dieback affects plants in all age classes, from seedlings, juveniles to adult plants, resulting in partial mortality of plants in all age categories over the trial period. Contrary to expectations, none of the biotic and abiotic factors examined showed a direct relationship to the changing population dynamics of M. pigra dieback over time. Nevertheless, fungal isolations demonstrated that M. pigra is a host to a diverse range of endop...

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“…We assessed the effect of treatment on log-transformed dry weight, number of seeds and total raceme length by linear mixed effect models using log-transformed initial volume of the seedling (calculated as volume=height×π×(0.25×width) 2 ) as a covariate and tray as a random effect. For each response variable we created a set of models including all relevant combinations of treatment, seedling volume and their interaction, or no factor (the null-model) as fixed effects, and fitted them with Maximum Likelihood to allow model comparison.…”

Section: Statisticsmentioning

confidence: 99%

Direct effects of insecticides on common ragweed-implications for natural enemy exclusion trials

et al. 2018

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Experimentally applying pesticides is an important method to assess the efficacy of weed biocontrol agents, but potential direct effects of the chemicals on plant performance are controversial or unknown. We assessed how three broad-spectrum insecticides applied in combination affect the performance of the widely invasive, crop-yield reducing, allergenic common ragweed (Ambrosia artemisiifolia L.) in an insect-free environment. Spraying insecticides had no significant effects on aboveground dry weight, seed and pollen output or pollen allergenicity, and only explained 1-8% of variation in these parameters. Our insecticide treatment can hence be applied to assess biocontrol impact on biomass and reproductive output of common ragweed. As our insecticide treatment delayed senescence, however, other methods of insect exclusion should be preferred when studying common ragweed phenology.

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Review of approaches to evaluate the effectiveness of weed biological control agents

Cited by 132 publications

References 166 publications

Explaining variability in the production of seed and allergenic pollen by invasive Ambrosia artemisiifolia across Europe

Explaining variability in the production of seed and allergenic pollen by invasive Ambrosia artemisiifolia across Europe

Mimosa pigra dieback in the Northern Territory, Australia: Investigation into possible causes

Direct effects of insecticides on common ragweed-implications for natural enemy exclusion trials

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