Letters in Applied Microbiology (2005) 41, 428-433

X. Ni and D.A. Streett (2005)
Modulation of water activity on fungicide effect on Aspergillus niger growth in Sabouraud dextrose agar medium
Letters in Applied Microbiology 41 (5), 428-433
Abstract: Aims: To examine whether water activity (aw) in combination with low concentration of fungicides can be used to effectively control Aspergillus niger van Tieghem growth in cultural medium, the Sabouraud dextrose agar (SDA). The data would be used as baseline information for reducing A. niger contamination in insect artificial diets.
Methods and Results: Aspergillus niger was isolated from an insect artificial diet. Four concentration levels (i.e. 0, 1, 10 and 20 µmol) of two fungicides (i.e. amphotericin B and itraconazole) were tested against A. niger under four aw levels (i.e. 0·994, 0·961, 0·921 and 0·859) adjusted by including 0, 12·5, 25 and 38% of glycerol in the medium mixture. Aspergillus niger growth was significantly reduced at low fungicide concentration (1 µmol), and at reduced aw. The spore germination was prevented with either higher fungicide concentration (>10 µmol), or low aw in the medium (aw < 0·921). The two ecological determinants (fungicides and aw) showed a significant impact on A. niger survival in the medium (P < 0·0001). Itraconazole is more effective than amphotericin B in controlling A. niger contamination in the agar medium.
Conclusion: Adjustment of aw (with 12·5% of glycerol) in combination with 1 mol of itraconazole can effectively prevent A. niger growth in the SDA cultural medium.
Significance and Impact of the Study: Aspergillus niger contaminations have frequently affected the quality of insects produced from mass rearing facilities. Low aw in combination with low fungicide concentration has the potential to become one of the most cost-effective management strategies to prevent A. niger contamination in insect artificial diets. The effect of fungicides and low aw in artificial diets on insect biology needs to be further examined.
(The abstract is excluded from the Creative Commons licence and has been copied with permission by the publisher.)
Link to article at publishers website
Database assignments for author(s): Xinzhi Ni

Research topic(s) for pests/diseases/weeds:
control - general

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Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
	Aspergillus niger