Estimated Reduction in Stem Borer-Associated Maize Yield Losses Through Application of Natural Enemies in Kenya and Tanzania Under Current Climatic Conditions (1970-2000) and Different Climate Change Scenarios (2041-2060, 2081-2100)
Center for Development Research, Department Ecology and Natural Resources Management (ZEF C), University of Bonn
The research within the scope of which the presented data was generated was part of the funding initiative ‘Knowledge for Tomorrow-Cooperative Research Project in sub-Saharan Africa on Resource, their Dynamics, and Sustainability’ funded by the Volkswagen Foundation. The study aimed at investigating the uncertainties in the effectiveness of biological control of stem borers under different climate change scenarios in Kenya and Tanzania. Using the species distribution modelling approach MaxEnt, the research predicts the current and future distribution of three important lepidopteran stem borer pests of maize in eastern Africa, i.e., Busseola fusca (Fuller, 1901), Chilo partellus (Swinhoe, 1885) and Sesamia calamistis (Hampson, 1910), and two of their parasitoids used for biological control, i.e., Cotesia flavipes (Cameron, 1891) and Cotesia sesamiae (Cameron, 1906). Based on these potential distributions and data collected during household surveys with local farmers in Kenya and Tanzania, future maize yield losses are predicted considering three different Global Circulation Models (GCMs) for four different Shared Socioeconomic Pathway (SSP) scenarios (SSP1-2.6, SSP2-4.5, SSP 3-7.0, SSP5-8.5) and two time periods, i.e., 2041-2060 and 2081-2100. The reduction potential of stem borer-associated maize yield losses by application of parasitoids (in kg/ha) is extrapolated using previously estimated average maize yield losses in the study area and results from a 2018 household survey conducted by researchers from the International Centre of Insect Physiology and Ecology (icipe) under the cooperative project "Adaptation for Food Security and Ecosystem Resilience in Africa” (AFERIA) of icipe, the University of Helsinki and the University of York in which local farmers were asked to quantify the reduction of losses in maize yield by stem borer infestation through application of natural enemies. Based on these survey data, 95% confidence intervals (CIs) for maize yield losses were calculated. Potential to reduce yield losses by stem borers for all scenarios are given for mean, lower and upper bound of the CI. Quality/Lineage: Rasters showing reduction potential of stem borer-associated maize yield losses by application of parasitoids were calculated in RStudio using the 'raster' package. Three raster layers were multiplied to quantify the potential of parasitoid application to reduce maize yield losses by stem borer infestation: R(c,e)= B(c,e)*Y(c,p)*Pe where Rc,e represents the potential reduction of yield losses (kg/ha) for each grid cell c by natural enemy e, Bc,e = {1,0} indicates parasitoid presence or absence for each grid cell, Y(c,p) indicates maize yield losses (kg/ha) and Pe represents estimated potential yield losses reduction by the parasitoids (%).