Economic consequences of post-harvest insect damage in Rwandan common bean markets

Abstract Post-harvest losses have major economic consequences for smallholders in sub-Saharan Africa. One significant contributor to economic losses is price penalties for poor quality marketed grain. This study investigates farm-gate level discounts demanded by rural Rwandan bean traders for insect-damaged common beans. We use a simplified contingent valuation methodology with physical bean samples to elicit seasonal damage discount schedules based on data from 270 trader interviews in 25 regionally-diverse rural markets, in periods of both common bean abundance and scarcity. While levels of 5–10% insect damage can generally be sold with a moderate discount, beans with 20–30% insect damage are largely unmarketable. We model the physical and non-physical drivers of buying insect-damaged beans and, if so, the extent of discounts demanded. Results indicate that while insect damage levels play a central role, large volume traders penalize damage less while traders in the seed market, storing before re-sale, or purchasing heavily from farmers (vs. other traders) penalize damage significantly more. Findings help develop more evidence-based extension programming and methods could be adapted as an easily implemented and potentially insightful model for developing country agencies. Additionally, derived discount coefficients help evaluate the cost-effectiveness of technologies throughout the region which prevent post-harvest damage.