Region: East Africa > Kenya
Categorized: Biological control
Tagged:
A system dynamics model for pests and natural enemies interactions
Stemborers (Busseola fusca, Sesamia calamistis and Chilo partellus), the fall armyworm (Spodoptera
frugiperda) and associated parasitoids constitute an interacting system in maize fields in Kenya. This
work aims at developing and evaluating models that represent the evolution of those interactions by
applying system thinking and system dynamics approaches with its archetypes [causal loop diagram
(CLD), reinforcing (R) and balancing (B)] to analyse the population of these multi‑species systems.
The software Vensim PLE 8.0.9 was used to implement the models and carry out the simulations
of single‑ and multi‑species systems. The results showed that when a single pest species with its
associated parasitoids interact with the host plant, the species was able to establish and sustain by
cyclical relationship between populations of the pest and the associated parasitoids. However, in
multi‑ pest species systems, dominance of S. frugiperda and C. partellus over B. fusca and S. calamistis
was observed, but without extinction. However, there was a likelihood for B. fusca being displaced by
C. partellus. Overall, the models predict the co‑existence of fall armyworm with stemborer species as
an additional pest of maize in Africa that need to be considered henceforth in designing IPM strategies
in maize.
