Identification of Maize Insects and Fungi Affecting Sanitary and Physiological Quality of Stored maize Grains in Central Cote d'Ivoire

Mah A. Kakou, Nahoulé A. Adja, Félicia Johnson, Adjoa M.J. Kouadia, Eric-Olivier Tienebo, Kouakou T. Kouadio, Mathias Danho and Kouabenan Abo

Background and Objective: Maize is one of the most important food cereal crops. Unfortunately, in Cote d'Ivoire, maize storage is mainly impaired by biotic factors that are not well documented and controlled. Therefore, this study aimed to identify occurring insects and fungi and their respective impacts on the physiological and sanitary qualities of harvested maize grains. Materials and Methods: Six major producing zones in central Cote d'Ivoire were sampled during harvest. Sampled grains were stored in polypropylene bags for six months in laboratory conditions. The 18 out of36 bags, randomly selected, were treated with the insecticide PROTECT DP to control insects. Taxa of insects and fungi present in stored samples were morphologically identified using standard keys. Then, occurrence and relative abundance were recorded monthly for insects, while fungal occurrences and infection rates were assessed during a 7-days paper blotting germination test at the beginning and the end of the storage. Furthermore, moisture content and germination rate were recorded at the beginning and the end of the experiment. Results: Five insect species, Sitophilus zeamais, Tribolium castaneum, Oryzaephilus surinamensis, Cillaeus sp. and Ephestia cautella were observed. Sitophilus zeamais was found with the highest occurrence and relative abundance (respectively 57.1 and 98.02%). As for fungi, microscopic observations revealed occurrences of eight fungal species. Then six species (Aspergillus versicolor, A. flavus, A. terreus, Rhizopus sp., Fusarium sp. and one unidentified species) were constant (50% <Ci <100%), while one A. niger was common species (38.27±25.55) and Penicillium sp. was rarely encountered (3.7±4.9). The moisture contents at the end of the storage of the treated grains were close to those of grains before storage but significantly lower than those of the untreated grains. Besides, the germination rates at the end of the storage of the treated grains were similar to those of grains dried before storage but significantly higher than those of the untreated grains regardless of the sampled zones. Conclusion: Insects and fungi are the main biotic agents which deteriorate the quality of stored grains.

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