Estimated Maize Yield Losses by Stem Borers 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 overall 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. Stem borer-associated maize yield losses (in kg/ha) are extrapolated using data on average maize yield in the study area downloaded from MapSPAM and based on 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 losses in maize yield by stem borer infestation. Based on these survey data, 95% confidence intervals (CIs) for maize yield losses were calculated. Yield losses by stem borers for all scenarios are given for mean, lower and upper bound of the CI. Quality/Lineage: Rasters showing stem borer-associated maize yield losses were calculated in RStudio using the 'raster' package. Three raster layers were multiplied to quantify maize yield losses by the stem borer pests: Y(c,p)= A(c,p)*Mc*Lp where Yc,p represents yield losses (kg/ha) for each grid cell c and each stem borer species p, Ac,p= {1,0} indicates each stem borer species’ presence or absence for each grid cell, Mc indicates maize yield (kg/ha) for each cell and Lp representing estimated yield losses by each stem borer (%).