Investigation of the potential effect of insect infestation on mycotoxin levels in stored rice

Insect pest infestations of post-harvest grains encourage the establishment of fungi, leading to grain deterioration and mycotoxin production, threatening food safety, and their correlation remains insufficiently explored. Therefore, this study investigates the relationship between insect infestation and mycotoxin levels in stored rice. Twelve samples of stored rice were collected to identify insects and associated fungi. Accordingly, mycotoxins, specifically Aflatoxin and T-2 Toxin, were extracted from the samples and quantified using CD-ELISA. The study found that the highest percentage of insect infestation (81%) and weight loss (25.50%) were observed in samples infested with Sitophilus zeamais (L.) (SZ1). In comparison, the lowest infestation level (32%) and weight loss (9.6%) were recorded for Trogoderma granarium Everts (TG1). Generally, fungal contaminations were correlated positively with the severity of insect infestation, as the highest fungal colonies were isolated from samples infested with SZ1, with a total count of 27 colonies. Both Aspergillus niger and Fusarium sp., dominated the fungal population, accounting for 33.72% and 33.14%, followed by Penicillium digitatum and Rhizopus stolonifer, each contributing 11.63%. Additionally, mycotoxin detection confirmed the presence of Aflatoxin and T-2 toxins, with the highest concentrations (4.89 and 25.1 ppb) respectively, were detected in rice infested with SZ1, which exhibited the highest infestation rate (81%). This study underscores the complex relationship between insect infestation, fungal contamination, and mycotoxin production. This provides practical advice for farmers and grain storage managers on the importance of early monitoring and detection of common insect and fungal pests with effective integrated pest management strategies that can be implemented to protect post-harvest grains.