Quantifying the effect of fall armyworms on maize yields in a resource constrained economy: A case study in Zambia
Fall armyworm (FAW) is a voracious pest, which has ravaged maize yields in Sub-Saharan Africa since they were first reported in 2016. Their exact impact on maize yields is unclear, with a wide discrepancy in the existing estimates which suffer from potential endogeneity in self-reporting,measurement error and the lack of a standardized methodology. Studies that have attempted to measure the impact of FAW in Africa have generally found large effects.However, most these studies are constrained by using farmer perceptions and recall data, or estimate the losses using cross sectional data, raising concerns of endogeneity, since the environmental conditions conducive for maize production are also conducive for FAW infestations. This study quantifies the impact of FAW on Zambian maize yields while controlling for household fixed effects and year fixed effects on a national panel dataset covering 1,200 farmers over three years (2015/16, 2016/17 and 2017/18 agricultural seasons). To address possible endogeneity associated with reporting, I use the average prevalence of FAW presence or intensity at the camp level as an instrument for farm FAW exposure. I find that compared to household that had no FAW infestation cases, households who had severe intensity of FAW in their surrounding camp experienced an average of 39.2 percent lower maize yields. Furthermore, the impact of FAW for households who were more likely to report they had FAW when their camp was infested, experienced 83.1 percent lower maize yields on average. These results are robust to different fixed effects specifications.Following earlier evidence from crop science, I explore the effect of planting date and the use of hybrids on FAW damage. In terms of planting date, I find planting date and the use of hybrids did not significantly influence the damage caused by FAW infestations.Quantifying of the effect of FAW on maize yield may help target government responses and enable policy makers to determine the quantity of reserve food that would be required to by farmers affected by various intensities of FAW infestations. My research suggests interventions seeking to manage FAW infestations among smallholder farmers could benefit from improving access maize hybrid seeds that are more resistant to FAW as well as encouraging farmers on the importance of early planting.
University of Illinois - Urbana-Champaign
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University of Illinois at Urbana-Champaign