Optimizing spatial positioning of traps in the context of integrated pest management

Agricultural research often relies on methods and approaches to represent and explain complex agro-ecosystems processes. In the context of biological control, auto dissemination strategies have been widely embraced for the management of various pests. One such strategy is using traps that attract arthropods into the hub of fungal based entomopathogens. The trapped pests are infected with the entomopathogen, which can then disseminate it among its conspecifics after being released. Despite the potential of the technique, its adoption especially by smallholder farmers has been limited, most likely due to the lack of an efficient trap positioning strategy. In this study, we propose an approach to improve the field application of fungal-based bio-pesticides (entomopathogenic fungi or EPF) by optimizing the spatial distribution of traps. The optimal field distribution of traps can be determined based on the following steps: (i) a field experiment to assess the dispersal ability of the pest infected by an entomopathogenic fungi (EPF) and (ii) the model-based estimation of the optimum traps density and distribution per unit of space (ha, km²). Based on experimental data we applied nonlinear regression and spatial optimization processes to calculate the radius covered by one trap and to estimate the optimum number and spatial positioning of the traps. We applied the method to a case study using the fungal isolate ICIPE 62 to control the invasive fruit fly Bactrocera dorsalis. The research revealed that nine pheromone traps per ha are required with a spacing distance of 37.45 m between the traps. The proposed approach can also be applied to other pest species, to help farmers reduce the number of traps used on a farm and to assist researchers and policymakers to optimize auto dissemination strategies in the context of integrated pest management (IPM).