- PhD: Yves Fotso Fotso, University of Dschang, Jan. 2017-Jan. 2022
- Supervisors: B. Tsanou, S. Touzeau, F. Grognard, S. Bowong
- Partners: IRAD

Context
- Coffee: important cash crop for many countries in the tropics
- Borers (Hypothenemus hampei) mostly develop and feed in coffee berries, inducing great damages (reduction in berry quality and yield) and economic losses
- Control methods: insecticides vs cropping practices (removing dropped berries, strip-picking, stump pruning), trapping, biological control (parasitoid or predator insects, entomopathogenic fungi)
- Existing model(s): simulation model with crop growth and pest control [Gutierrez et al. 1998; Rodríguez et al. 2011; Rodríguez et al. 2013]
A.P. Gutierrez, A. Villacorta, J.R. Cure, C.K. Ellis. Tritrophic analysis of the coffee (Coffea arabica)-coffee berry borer [Hypothenemus hampei (Ferrari)]- parasitoid system. Anais da Sociedade Entomológica do Brasil 27(3): 357-385, 1998. DOI: 10.1590/S0301-80591998000300005
D. Rodriguez, J.R. Cure, J.M. Cotes, A.P. Gutierrez, F. Cantor. A coffee agroecosystem model: I. Growth and development of the coffee plant. Ecological Modelling 222(19): 3626-3639, 2011. DOI: 10.1016/j.ecolmodel.2011.08.003
D. Rodriguez, J.R. Cure, A.P. Gutierrez, J.M. Cotes, F. Cantor. A coffee agroecosystem model: II. Dynamics of coffee berry borer. Ecological Modelling 248: 203-214, 2013. DOI: 10.1016/j.ecolmodel.2012.09.015
Objectives
- To develop a model representing coffee berry borer damages in various agroforestry systems
- To design and assess the efficiency of several control strategies, including alternative methods to pesticides
Work progress
Achieved
First approach: single-season framework
- Single-season model of the coffee berry borer dynamics, based on the insect life-cycle and including the berry availability during a cropping season
- ODE model: local and global stability (Lyapunov functions) results for the pest-free and endemic equilibria
- PDE extension, to integrate the berry maturation age: well-posedness and asymptotic analysis
- Optimal control problem
- Controls: chemical control (insecticides) and/or biological control by entomopathogenic fungi such as Beauveria bassiana, traps
- Aim: to maximise the yield at the end of the cropping season, while minimising the borer population for the next cropping season and the control costs
- Results: existence of an optimal solution, numerical solution using the BOCOP software
- Bounded control, no persistence
Y. Fotso, F. Grognard, B. Tsanou, S. Touzeau. Modelling and control of coffee berry borer infestation. Paper and oral presentation in: CARI’2018 – 14th African Conference on Research in Computer Science and Applied Mathematics, Stellenbosch, South Africa, 14-16 October 2018. HAL Id: hal-01871508
Y. Fotso Fotso, S. Touzeau, S. Bowong, F. Grognard, L. Mailleret, B. Tsanou. Modelling and control of coffee berry borer infestation. Contributed talk in: ECMTB 2018 – 11th European Conference on Mathematical and Theoretical Biology, Lisbon, Portugal, 23-27 July 2018. HAL Id: hal-01859994
- Control persistence: the impact of entomopathogenic fungi (or insecticides) lasts over time
F. Grognard, I. Tankam Chedjou, Y. Fotso Fotso, S. Touzeau. Modelling, control, and optimization for tropical agriculture. Oral presentation in: CMPD5 – Computational and Mathematical Population Dynamics, Fort Lauderdale, USA, 19-24 May 2019. HAL Id: hal-02139546
Y. Fotso Fotso, F. Grognard, S. Touzeau, B. Tsanou, S. Bowong. Optimal control on a simple model of coffee berry borer infestation. Oral presentation in: BIOMATH 2019 – International Conference on Mathematical Methods and Models in Biosciences, Bȩdlewo, Poland, 16-22 June 2019. HAL Id: hal-02309445
Y. Fotso Fotso, S. Touzeau, B. Tsanou, S. Bowong, F. Grognard. Modelling and optimal strategy to control coffee berry borer infestation. Mathematical Methods in the Applied Sciences 44(18):14569-14592, 2021. DOI: 10.1002/mma.7726. HAL Id: hal-03334090
- “Pré-soutenance” passed 6 October 2021, PhD defence 17 January 2022 (postponed due to pandemic)
Yves Fotso Fotso. Modelling, analysis and control of coffee berry borer. University of Dschang, Cameroon, 2022. HAL Id: tel-03608463
Ongoing work
Model extensions
- Introduction of CBB preference for mature berries (PDE model with berry age structure)
Yves Fotso Fotso, Suzanne Touzeau, Berge Tsanou, Frédéric Grognard, Samuel Bowong. Mathematical modelling of a pest in an age-structured crop model: the coffee berry borer case. Preprint, 2022. HAL Id: hal-03505679
- Seasonal model to represent several cropping seasons and harvests (hybrid model)
Misc
- Participation in the École de Contrôle Optimal Numérique, Toulouse, 3-7 September 2018 (grant)
- Fellow of the AUF Collège doctoral régional de l’Afrique Centrale et des Grands Lacs « Mathématiques, Informatique, Biosciences et Géosciences de l’Environnement », June 2018 call
- Participation in the International Graduate School on Control, M18 Hybrid Control Design, L’Aquila, Italy, 13-17 May 2019 (overseas grant)