Entomofauna, mycotoxin accumulation and storage loss dynamics in cereals in the Tshopo province, Democratic Republic of Congo

Abstract

Post-harvest losses of cereals remain a major challenge for food security in tropical regions, yet data from Central Africa are scarce. This study investigated the entomofauna, mycotoxin contamination, and storage loss dynamics of rice (Oryza sativa L.) and maize (Zea mays L.) stored under traditional conditions in the Tshopo province, Democratic Republic of Congo. Cereals were sampled at nine storage sites across three zones at 0, 30, and 60 days of storage. Insect pests were identified using morphological and molecular approaches, mycotoxins were quantified using immunochromatographic assays validated by UHPLC–MS/MS, and grain quality losses were assessed through weight, moisture, integrity, and germination measurements.

Stored cereals were dominated by three insect pests: Sitophilus zeamais, Sitotroga cerealella, and Tribolium castaneum, accounting for more than 98% of all collected insects. S. zeamais was ubiquitous and reached high densities in both crops, while S. cerealella showed site-specific infestations, particularly in rice. Aflatoxin contamination was detected in both crops and increased significantly during maize storage, frequently exceeding the European regulatory limit after 60 days in some zones. Fumonisins were detected exclusively in maize at low but consistent concentrations. Grain moisture readings point to a high risk of pre-storage mycotoxin accumulation, with additional in-storage aflatoxin production occurring specifically in stores with the highest moisture levels. Grain quality deteriorated during storage, with significant losses in dry weight, integrity, and germination capacity, particularly in sites with high insect pressure and mycotoxin levels. Correlation analyses revealed strong associations between insect abundance, mycotoxin accumulation, grain moisture content, and grain deterioration. Findings demonstrate that post-harvest losses in stored rice and maize in Tshopo province are driven by synergistic interactions between storage pests and fungal contamination. The study provides the first comprehensive baseline data for the region and highlights the urgent need for improved storage management to reduce food safety risks and cereal losses.