Modelling effects of vector acquisition threshold on disease progression in a perennial crop following deployment of a partially resistant variety

Abstract

Deployment of resistant varieties is a key strategy to mitigating economic losses due to arthropod‐transmitted plant pathogens of perennial crops. In many cases, the best available resistant traits for introgression confer only partial resistance. Plants displaying partial resistance have lower pathogen titres than susceptible counterparts, but remain hosts for the pathogen. As partially resistant varieties maintain yield after infection, infected plants are unlikely to be rogued (i.e. removed). Accordingly, there is a risk that partially resistant plants could serve as a source of inoculum for pathogen spread to susceptible plants. Here, a mathematical model that tracked spread of an arthropod‐transmitted pathogen in a plant population consisting of susceptible and partially resistant plants was used to identify a threshold acquisition rate from partially resistant plants that resulted in limited spread of the pathogen from partially resistant plants to susceptible plants. The acquisition threshold from partially resistant plants varied with parameters influenced by disease management decisions such as number of vectors per plant, vector turnover, replacement of susceptible plants, and proportion of plants that were partially resistant. In model simulations, effects of deploying a partially resistant variety on disease incidence in a susceptible variety depended on the extent to which pathogen spread among susceptible plants was suppressed and acquisition rates from partially resistant plants. Collectively, the results indicate that risk of partially resistant plants serving as inoculum sources could be assessed prior to deployment, thereby enabling design of complementary disease management tactics to minimize economic losses in susceptible varieties following deployment.

Impact ofXylella fastidiosasubspeciespaucain European olives

“…While full resistance is achievable, partial resistance or reductions in full-bearing yields might be the outcome of breeding efforts. In addition, tolerant cultivars remain hosts for the pathogen and are inoculum reservoirs (49), which might support disease spread. Lastly, vigilant growers might aim to stay ahead of the disease by additional monitoring efforts and preventive measures prior to their orchards being infected.…”

Plant defense against a pathogen drives nonlinear transmission dynamics through both vector preference and acquisition

“…Vector‐borne plant pathogens threaten agricultural sustainability, and development of disease‐resistant cultivars for agricultural species provides an important management alternative to insecticides. At the same time, partially resistant or tolerant cultivars could—according to theoretical predictions—increase the risk of disease spread and spillover to more susceptible hosts (Zeilinger and Daugherty 2014, Sisterson and Stenger 2018). In the context of such epidemic risks, we tested the impacts of the PdR1 resistance trait in grapevines on transmission of the bacterial pathogen X. fastidiosa by the insect vector G. atropunctata .…”

“…On the other hand, pathogen spread can be greatly enhanced when hosts are tolerant to infection and when vectors avoid diseased hosts. Understanding the precise interplay between host defense and vector transmission can improve disease management because of their influence on the risk of disease spillover from partially resistant or tolerant hosts into nearby susceptible host populations (Sisterson and Stenger 2018).…”

Xylella fastidiosa and Glassy-Winged Sharpshooter Population Dynamics in the Southern San Joaquin Valley of California

“…al. 2007;Sisterson and Stenger 2018). Although mathematical simplifications are often justified, it should be recognized that assumptions of fixed vector population size and fixed acquisition rates are biologically unrealistic.…”