Clotilde Djuikem

PhD

Clotilde Djuikem
  • Université Côte d’Azur, France, Oct. 2019-Jan 2023 (Inria CORDI grant)
  • Title: Mathematical modelling and control of perennial plant phytopathogens
  • HAL: tel-04026720
  • Supervisors: F. Grognard, S. Touzeau, S. Bowong

Context

  • Coffee: cash crop for tropical developing countries – 25 million households [FAO]
  • Coffee leaf rust (CLR): caused by fungus Hemileia vastatrix
    • premature defoliation, flower & fruit abortion, shoot desiccation
    • major coffee leaf disease – yield loss up to 75%
  • Control methods
    • quarantine: to limit invasions
    • chemical fungicides: limited effectiveness (rain), toxicity, resistance
    • cultural practices (shading, pruning): as complement
    • resistant cultivars: resistance in Coffea wild species
    • biocontrol agents
      • antagonist bacteria that enhance resistance to fungus: e.g. Bacillus species
      • hyperparasites that feed on rust spores: fungi such as Lecanicillium lecanii, insects such as Mycodiplosis (Diptera)

Objectives

  • Develop a model representing coffee leaf rust (CLR) damages in a coffee plantation
  • Design efficient and sustainable control strategies, based on alternatives to fungicides

Results

Epidemiological modelling of coffee rust spread

  • Classical SEIR model (ODE model) with
    • free fungus spore compartment to spread the disease
    • young and mature leaves to represent stage-dependent crop response to fungus (infection and sporulation rates)
    • berry compartment to assess the impact of CLR on crop production
  • Bifurcation analysis to study disease persistence

C. Djuikem, F. Grognard, S. Touzeau. Impact of ontogenic changes on the dynamics of a fungal crop disease model motivated by coffee leaf rust. Journal of Mathematical Biology 88(3):30, 2024. DOI: 10.1007/s00285-024-02053-4. HAL: hal-04484395

  • Spatio-temporal PDE model for dry and rainy seasons (PDE model)

C. Djuikem, F. Grognard, R. Tagne, S. Touzeau, S. Bowong. Modelling coffee leaf rust dynamics to control its spread. Mathematical Modelling of Natural Phenomena 16:26, 2021. DOI: 10.1051/mmnp/2021018. HAL: hal-03188365

Implementing sustainable control methods

  • Hybrid model: multi-seasonal framework with continuous dynamics during the production seasons and a discrete events during the dry seasons
  1. Continuous control: optimal control to maximise profit

C. Djuikem, A. Yabo, F. Grognard, S. Touzeau. Mathematical modelling and optimal control of the seasonal coffee leaf rust propagation. In: ADHS 2021 – 7th IFAC Conference on Analysis and Design of Hybrid Systems, Brussels, Belgium, 2021. IFAC-PapersOnLine 54(5):193-198, 2021. DOI: 110.1016/j.ifacol.2021.08.497. HAL: hal-03274865

  1. Impulsive control: release frequency of biocontrol agent

C. Djuikem, F. Grognard, S. Touzeau. Impulsive modelling of rust dynamics and predator releases for biocontrol. Mathematical Biosciences 356:108968, 2023. DOI: 10.1016/j.mbs.2023.108968. HAL: hal-03952381

Misc

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