Vip3Aa and Cry1Ab proteins in maize reduceFusarium ear rot and fumonisins by deterring kernel injury from multiple Lepidopteran pests

Abstract

Field trials were conducted in 2008, 2009 and 2011 to assess fumonisin contamination in transgenic (Bt) and non- Bt maize hybrids infested with European corn borer, corn earworm, and Western bean cutworm. Comparisons were made among maize hybrids expressing two transgenic insect resistance proteins (Cry1Ab × Vip3Aa), a single resistance protein (Cry1Ab), or no insect resistance. The field design was a randomised complete block design with four replicates of each hybrid × insect combination. Kernel injury, Fusarium ear rot, and fumonisins (FB1+FB2+FB3) in maize grain were measured. These measurements differed significantly among years of the study. In all years, significant positive correlations were present between insect injury and Fusarium ear rot, insect injury and grain fumonisin levels, and Fusarium ear rot and grain fumonisin levels. Under all insect infestation treatments, Cry1Ab × Vip3Aa hybrids were the most resistant of the hybrids with regard to any of the grain quality measurements. Averaged over all insect infestations and years, insect injury, Fusarium ear rot, and grain fumonisin levels were all low in Cry1Ab × Vip3Aa (0.1% and 2.2% of total kernels, and 0.56 mg/kg, respectively). The highest average levels of insect injury, Fusarium ear rot, and grain fumonisin contamination (3.3% and 7.2% of total kernels, and 5.47 mg/kg, respectively) were found in the non-Bt hybrids. The presence of transgenic insect protection (Cry1Ab × Vip3Aa or Cry1Ab) resulted in significant reductions in all grain quality measurements as compared with the non- Bt hybrids. Only grain obtained from Cry1Ab × Vip3Aa hybrids consistently had acceptable fumonisin content according to both US guidance levels and EU regulatory limits. These results indicate that Cry1Ab × Vip3Aa maize hybrids are more likely to yield high quality, low-fumonisin grain compared to hybrids expressing only Cry1Ab or lacking insect resistance.

Larval western bean cutworm feeding damage encourages the development of Gibberella ear rot on field corn

“…Our results parallel those of others examining WBC and its association with ear rots. In one study, Bowers et al found similar trends, whereby greater kernel injury attributed to WBC (and other ear‐feeding Lepidoptera) led to increased levels of Fusarium ear rot and subsequent higher levels of fumonisins in grain. Importantly, both of these studies were focused chiefly upon quantifying Bt hybrid treatment differences with respect to the presence of Cry toxins targeting lepidopteran pests, and in both cases it was demonstrated that targeting larvae with these hybrids effectively reduced the incidence of the disease and mycotoxins.…”

Delaying harvest for naturally drying maize grain increases the risk of kernel rot and fumonisin contamination

“…Inverse results were observed for the hybrid Attack, which presented low incidence of kernel rot and higher levels of fumonisin in the grains. Although F. verticillioides and fumonisins may be found in asymptomatic corn grains (Lanza et al 2017), high levels of fumonisins are commonly associated with ear rot incidence (Bowers et al 2013). According to Parsons and Munkvold (2010), grains showing physical injuries have a higher incidence of ear rot and contamination with fumonisins than undamaged grains.…”

“…According to Parsons and Munkvold (2010), grains showing physical injuries have a higher incidence of ear rot and contamination with fumonisins than undamaged grains. In particular, insect-damaged grains are more likely to be contaminated with fungi and mycotoxins (Bowers et al 2013). According to these authors, the use of transgenic hybrids expressing the Cry1AB x Vip3Aa genes reduced the fumonisin content in the grains when compared to hybrids expressing only the Cry1AB gene or non-transgenic hybrids.…”

“…The fumonisin B1 (FB1) is the most frequent and highly toxic, but FB2 and FB3 are also found eventually (Marasas 2001;Samapundo et al 2006;Yılmaz and Tuncel 2010;Bowers et al 2013;Guo et al 2016). FB1 is classified as a human carcinogen (Group 2B) by the International Agency for Research on Cancer (IARC) and is associated with several animal diseases (Jackson and Jablonski 2004;Lanza et al 2017;Lerda 2017).…”

Mycotoxins that affect the North American agri-food sector: state of the art and directions for the future

“…Currently, biotechnology developers are stressing the use of insecticidal proteins other than Cry1Ab, or using newer traits together with Cry1Ab, in combinations that provide resistance to the full range of Lepidopteran pests. Fumonisin levels in these hybrids have been extremely low in field trials (Bowers et al, 2013), and they show increased capacity to reduce aflatoxin levels as well.…”