Extending the durability of cultivar resistance by limiting epidemic growth rates

Carolan, Kevin; Helps, Joseph; Berg, Femke van den; Bain, R. A.; Paveley, N. D.; Bosch, Frank van den

doi:10.1098/rspb.2017.0828

Cited by 29 publications

(29 citation statements)

References 23 publications

(25 reference statements)

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“…The experimental data required to estimate parameters are relatively simple to obtain and analysis is straightforward. Models to describe the joint action of fungicides mixtures, based on MSM principles, have been included as a component in decision support system models for winter wheat disease control (Paveley et al ., ; Milne et al ., ) and models of pathogen evolution that consider integrated control (Carolan et al ., ).…”

Section: Discussionmentioning

confidence: 97%

Integrated control of potato late blight: predicting the combined efficacy of host resistance and fungicides

et al. 2018

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Integrating cultivars that are partially resistant with reduced fungicide doses offers growers an opportunity to decrease fungicide input but still maintain disease control. To use integrated control strategies in practice requires a method to determine the combined effectiveness of particular cultivar and fungicide dose combinations. Simple models, such as additive dose models (ADM) and multiplicative survival models (MSM), have been used previously to determine the joint action of two or more pesticides. This study tests whether a model based on multiplicative survival principles can predict the joint action of fungicide doses combined with cultivars of differing partial host resistance. Data from eight field experiments on potato late blight (Phytophthora infestans) were used to test the model; the severity of foliar blight was assessed and scores used to calculate the area under the disease progress curve (AUDPC). A subset of data, derived from the most susceptible cultivar, King Edward, was used to produce dose-response curves from which parameter values were estimated, quantifying fungicide efficacy. These values, along with the untreated values for the more resistant cultivars, Cara and Sarpo Mira, were used to predict the combined efficacy of the remaining cultivar by fungicide dose combinations. Predicted efficacy was compared against observations from an independent subset of treatments from the field experiments. The analysis demonstrated that multiplicative survival principles can be applied to describe the joint efficacy of host resistance and fungicide dose combinations.

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Section: Discussionmentioning

confidence: 97%

Integrated control of potato late blight: predicting the combined efficacy of host resistance and fungicides

et al. 2018

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“…As the world anticipates feeding nine billion people as sustainably as possible by 2050, crop protection against pest insects, diseases and weeds has a vital role in maintaining and improving crop yields (Godfray et al, 2010). Whilst awareness is growing of the importance of integrated pest management, pesticides remain a necessary part of the pest-control toolbox for many crops (Swanton et al, 2011), in combination with other approaches such as disease-resistant crop varieties (Carolan et al, 2017). However, just as the effectiveness of antibiotics in the control of human disease is under threat due to the evolution of resistant strains of bacteria (World Health Organisation, 2014), the control of agricultural pests and crop diseases is threatened by the evolution of pesticide resistance, affecting insecticides (Bass et al, 2015), herbicides (Powles & Yu, 2010) and fungicides (Lucas, Hawkins & Fraaije, 2015).…”

Section: Introduction: Evolution Of Pesticide Resistancementioning

confidence: 99%

The evolutionary origins of pesticide resistance

et al. 2018

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Durable crop protection is an essential component of current and future food security. However, the effectiveness of pesticides is threatened by the evolution of resistant pathogens, weeds and insect pests. Pesticides are mostly novel synthetic compounds, and yet target species are often able to evolve resistance soon after a new compound is introduced. Therefore, pesticide resistance provides an interesting case of rapid evolution under strong selective pressures, which can be used to address fundamental questions concerning the evolutionary origins of adaptations to novel conditions. We ask: (i) whether this adaptive potential originates mainly from de novo mutations or from standing variation; (ii) which pre-existing traits could form the basis of resistance adaptations; and (iii) whether recurrence of resistance mechanisms among species results from interbreeding and horizontal gene transfer or from independent parallel evolution. We compare and contrast the three major pesticide groups: insecticides, herbicides and fungicides. Whilst resistance to these three agrochemical classes is to some extent united by the common evolutionary forces at play, there are also important differences. Fungicide resistance appears to evolve, in most cases, by de novo point mutations in the target-site encoding genes; herbicide resistance often evolves through selection of polygenic metabolic resistance from standing variation; and insecticide resistance evolves through a combination of standing variation and de novo mutations in the target site or major metabolic resistance genes. This has practical implications for resistance risk assessment and management, and lessons learnt from pesticide resistance should be applied in the deployment of novel, non-chemical pest-control methods.

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“…The life cycle also plays a role in the frequency of observation of evolutionary rescue effects. Carolan et al (2017) highlighted the impact of the growth rate of the pathogen on resistance durability, by presenting the limitation of the growth rate as a mean to increase resistance durability. In accordance with this study, we displayed a growth rate threshold r 0 below which the pathogen population goes extinct if it does not invade the resistant compartment.…”

Section: Life Cycles Impose Different Selection Regimes and Lead To Contrasted Evolutionary Trajectoriesmentioning

confidence: 99%

“…This observation raises the question of resistance durability, which can be defined as the time until the virulent population reaches a given threshold in the pathogen population. Definitions of resistance durability can have diverse acceptations depending on the threshold considered (Van den Bosch et al 2003;Pietravalle et al 2006;Brown 2015;Carolan et al 2017;Lof et al 2017b;Pacilly et al 2018;Rimbaud et al 2021). Considering several thresholds can help in capturing different steps of the pathogen dynamics.…”

Section: Introductionmentioning

confidence: 99%

Impact of ploidy and pathogen life cycle on resistance durability

Saubin

Mita

Zhu

et al. 2021

Preprint

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The breeding of resistant hosts based on the gene-for-gene interaction is crucial to address epidemics of plant pathogens in agroecosystems. Resistant host deployment strategies are developed and studied worldwide to decrease the probability of resistance breakdown and increase the resistance durability in various pathosystems. A major component of deployment host strategies is the proportion of resistant hosts in the landscape. However, the impact of this proportion on resistance durability remains unclear for diploid pathogens with complex life cycles. In this study, we modelled pathogen population dynamics and genetic evolution at the virulence locus to assess the impact of the ploidy (haploid or diploid) and the pathogen's life cycle (with or without host alternation) on resistance durability. Ploidy has a strong impact on evolutionary trajectories, with much greater stochasticity and delayed times of resistance breakdown for diploids. This result emphasizes the importance of genetic drift in this system: as the virulent allele is recessive, positive selection on resistant hosts only applies to homozygous (virulent) individuals, which may lead to population collapses at low frequencies of the virulent allele. We also observed differences in the effect of host deployment depending on the pathogen's life cycle. With host alternation, the probability that the pathogen population collapses strongly increases with the proportion of resistant hosts in the landscape. Therefore, resistance breakdown events occurring at high proportions of resistant hosts frequently amount to evolutionary rescue. Last, life cycles correspond to two selection regimes: without host alternation (soft selection) the resistance breakdown is mainly driven by the migration rate. Conversely, host alternation (hard selection) resembles an all-or-nothing game, with stochastic trajectories caused by the recurrent allele redistributions on the alternate host.

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Extending the durability of cultivar resistance by limiting epidemic growth rates

Cited by 29 publications

References 23 publications

Integrated control of potato late blight: predicting the combined efficacy of host resistance and fungicides

Integrated control of potato late blight: predicting the combined efficacy of host resistance and fungicides

The evolutionary origins of pesticide resistance

Impact of ploidy and pathogen life cycle on resistance durability

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