Yves defended his PhD thesis at the University of Dschang on January 17th 2022.
He worked on the modelling, analysis and control of coffee berry borer.
ABSTRACT – Coffee production is an important agricultural activity, in particular in several developing countries. For decades in Cameroon, coffee has been a proven cash crop and continues to be grown despite the fact that production basins have been reduced to make way for food crops. A major threats on coffee production is the serious damage caused by a small insect, Hypothenemus hampei called coffee berry borer (CBB). This insect is very difficult to control as it reproduces and spends most of its life cycle inside the coffee berry. It hence causes severe crop losses. The objective of this thesis is to develop mathematical models for the study, understanding and control of the dynamics of CBB in its ecosystem through theoretical and numerical developments. After a brief presentation of the biology of the interaction between coffee berries and CBB, a basic model is proposed. This model is governed by a non-linear system of ordinary differential equations that describes the infestation dynamics of coffee berries by CBB over a cropping season, taking into account berries availability. Based on the knowledge that berry preference is age-dependent during the selection and infestation process of colonising CBB, our basic model is then extended into a system of partial differential equations with an age structure of the coffee berries. Since the ultimate goal of coffee producers is to produce high quality coffee at the best market price and at the lowest cost, we design optimal control strategies based on the use of environmentally friendly methods such as trapping and release of phytopathogenic fungi.
The objective of these control strategies is to maximise yield while minimising control costs and the CBB population for the next cropping season. An extended modelling approach based on the basic model taking into account the fruiting period of coffee berries and multiple cropping seasons is then proposed and studied. By using cultural control, which consists of a thorough harvesting of berries at the end of each production period and a cleaning of the plantation during the intercropping, we determine the criteria for extinction of the CBB population over several seasons. On the agronomical front, the main outputs of this thesis consists in the analysis of the dynamics of CBB-berries interaction over several seasons, but also the emphasis on the advantage of using more than one economically friendly CBB control methods simultaneously.
Yves Fotso Fotso. Modelling, analysis and control of coffee berry borer. University of Dschang, Cameroon, 2022. HAL Id: tel-03608463
