The Effect Of Different Factors On Fumonisin Contamination In Corn

The corn is a major food and feed crop in our country, which is also one of thethree major crops in the world. Maize ear rot is an important disease affecting maizeproduction and quality, and more importantly, Fumonisins（FBs） produced by ear rotpathogens have a strong impact on corn edibleness and vendibility. Fumonisins arecarcinogenic mycotoxins produced by Fusarium verticillioides and Fusariumproliferatum as secondary metabolites. FBs have not only been shown to induce thefatal disease syndromes: equine leukoencephalomalacia and porcine pulmonaryedema, but also have been linked with an increased risk of esophageal cancer inhumans. Based on their toxicity, FB₁has been classified by International Agency forResearch on Cancer （IARC） as possibly carcinogenic in humans （Group2B）. In ourcountry, the prevention and treatment of corn disease and insect pests will be ahotspot on corn study with the development of economy and the regulation ofeconomic structure. However, the relationship between corn disease and insect pests,the occurrence of maize ear rot, as well as fumonisins contamination has merelyreported. In this study, cotton bollworm and corn borer were as test insects and wedetected the effect of pests, pathogenic bacteria, and climate conditions on maize earrot and fumonisins contamination at silking stage by inoculating or co-inoculating twostrains of F. verticillioides which had different toxin-producing ability. What’s more,we evaluated the contamination of fumonisins B₁and B₂in corn in Inner Mongolia,Gansu, Ningxia, Henan, Hebei, and Shandong provinces. The results of study were asfollows:Pests and pathogens can increase the occurrence of maize ear rot and the level offumonisins. Cotton bollworms are more sensitive than corn borer and grow inappropriate temperature，precipitation and relative humidity。Corn borers are lesssensitive to precipitation and relative humidity。The volatility of temperature，precipitation and relative humidity has merely effect on corn borers。In the conditionof same pests,high precipitation and high humidity promoted the occurrence of maizeear rot.therefore, to reduce the occurrence of ear rot in different climate，we shouldprevent main pests and enhance field management controlling density of planting andimproving ventilation and transmittancy. The pathogenicity of pathogens andtoxin-producing ability were mainly controlled by their own conditions and had lessrelation with climate conditions. The study was undertaken to evaluate the natural occurrence of fumonisins B₁and B₂in corn from Inner Mongolia, Gansu, Ningxia, Henan, Hebei, and Shandongprovinces. Fumonisin levels in the three studied provinces varied from region toregion in occurrence and mean. This detectable spread of fumonisin was high inLiaocheng，Shandong province （81.1%for FB₁and67.9%for FB₂） when compared toGansu （24.5%for FB₁and16.0%for FB₂）, Ningxia （19.2%for FB₁,42.3%for FB₂）,Inner Mongolia （FB₁:53.6%, FB₂:42.9%）, Hebei（FB₁:38.9%, FB₂:22.2%） andHenan（FB₁:50.0%, FB₂:20.0%）. The samples from Shandong had total fumonisins（FB₁and FB₂） concentration exceed the American limits of2000μg/kg. The totalfumonisins of all provinces were lower than Europe limits of4000μg/kg. The meanlevels of fumonisins in Inner Mongolia, Gansu, Ningxia, Henan, Hebei, and Shandongprovinces were1399,175,373,354,251and2496μg/kg respectively.