Influence of Bt and environmental factors on Fusarium ear rot in maize

Fusarium verticillioides is responsible for Fusarium ear rot (FER) and fumonisin (FUM) in maize (Zea mays L.). Multiple factors, including drought stress, humidity, and insects, influence the severity of FER and FUM. This study aimed to assess the occurrence and severity of FER, FUM, and corn earworm (Helicoverpa zea Boddie) feeding in Bt and non-Bt maize grown on commercial farms in North Carolina. We attempt to identify important environmental factors specific to maize growth stages that contribute to FER and FUM. Two Bt and three non-Bt hybrids were sampled in 50 environments in North Carolina for FER and FUM under natural infection. Bt hybrids had 7.2% ear rot compared to 11.7% for non-Bt hybrids. For corn earworm feeding, Bt hybrids had 1.5 cm2 per ear of feeding damage compared to 4.2 cm2 per ear for non-Bt hybrids. Although differences in FUM were not significant, Bt hybrids had a numerically lower FUM than non-Bt hybrids. In some counties and years, the FUM levels exceeded those recommended for products intended for human and animal consumption, with the highest level recorded at 27.8 ppm in a non-Bt hybrid. We identified several environmental covariates related to FER, FUM, and corn earworm feeding. The results highlight the complexity of ear rots, mycotoxin, and insects and their interaction in maize. It also highlights a need for a larger sample size in multiple environments with adequate variation in FER, FUM, and insect feeding to tease apart factors influencing ear rots and mycotoxins.轮状镰刀菌（Fusarium verticillioides）可引发玉米（Zea mays L.）的镰孢穗腐病（Fusarium ear rot, FER）与伏马毒素（fumonisin, FUM）污染。干旱胁迫、湿度条件、虫害等多种因素，均会影响镰孢穗腐病与伏马毒素污染的发生严重程度。本研究旨在评估北卡罗来纳州商业农场种植的转Bt基因（Bt）与非转Bt基因（non-Bt）玉米的镰孢穗腐病、伏马毒素污染发生情况，以及玉米穗虫（Helicoverpa zea Boddie）的取食危害程度，并尝试鉴定与玉米生育期相关的、影响镰孢穗腐病与伏马毒素污染的关键环境因子。研究在北卡罗来纳州的50个试验环境中，对2个转Bt基因杂交品种与3个非转Bt基因杂交品种开展了自然感染条件下的镰孢穗腐病与伏马毒素采样分析。结果显示，转Bt基因杂交品种的穗腐病发生率为7.2%，而非转Bt基因杂交品种的发生率为11.7%；在玉米穗虫取食危害方面，转Bt基因品种每穗的取食损伤面积为1.5 cm²，非转Bt基因品种则为4.2 cm²。尽管伏马毒素含量的组间差异未达统计学显著性，但转Bt基因品种的伏马毒素含量在数值上低于非转Bt基因品种。在部分县份与年度中，伏马毒素含量超出了供人类及动物食用产品的推荐安全限量，其中一例非转Bt基因杂交品种的伏马毒素最高记录值达27.8 ppm。本研究鉴定出了与镰孢穗腐病、伏马毒素污染及玉米穗虫取食相关的多项环境协变量。研究结果凸显了玉米穗腐病、真菌毒素与虫害及其相互作用的复杂性，同时也指出，需在镰孢穗腐病、伏马毒素污染与虫害取食存在足够变异的多环境中开展更大样本量的研究，以厘清影响穗腐病与真菌毒素积累的各类因素。