INSECT AND MYCOFLORA INTERACTIONS IN MAIZE FLOUR

Abstract

Maize flour treated with or without Tribolium castaneum was investigated for the presence of some fungi. Fusarium moniliforme had the highest occurrence of 36.7%, 28.1% and 33.3% while Aspergillus flavus/parasiticus had a frequency of 3.2%, 3.1% and 3% on primary isolation media of czapek dox agar (CDA), potato dextrose agar (PDA) and sabouraud dextrose agar (SDA) respectively, in maize flour without T. castaneum. The frequency of F. moniliforme reduced in maize flour with T. castaneum to 11.1%, 12.1% and 18.8% on CDA, PDA and SDA while A. flavus/parasiticus increased in occurrence after introducing T. castaneum to 22.2%, 18.2% and 12.3% on the three respective media. Fourteen and 7 fungal genera were isolated from maize flour with and without F. castaneum respectively. Two fungal species isolated from maize flour without T. castaneum were Cladosporium cladosporioides and C. lunata. Ten species isolated from maize flour with T. castaneum were A. pullulans, Auxarthron spp., C. herbarum, Eurotium sp., Phoma glomerata, Neosauorya spp., Scopulariopsis brevicaulis, Rhizopus oryzae, R. stolonifer and Wallemia sebi. These results suggest an association and a synergistic interaction between important spoilage and mycotoxigenic fungi with T. castaneum such as A. flavus/parasiticus and some mildly parasitic fungal colonies but an antagonistic interaction with F. moniliforme.


Key words: Tribolium castaneum, storage fungi, synergistic/antagonistic interactions, mycotoxins


(Af. J. Food and Nutritional Sciences: 2001 1(1): 3-8)