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SESSION 5: DISEASE CONTROL AND FORECASTING MODELS
P133 - Busseola fusca and Fusarium verticillioides
interaction on Fusarium ear rot and fumonisin
production in Bt and non-Bt maize hybrids in South
Africa
E. Ncube 1 , B. C. Flett 1,2 , J. van den Berg 2 , J. B. J. van Rensburg 1 , A. Viljoen 3
1 ARC-Grain Crops Institute, Private Bag X1251, Potchefstroom, 2520, South Africa, 2 Unit of
Environmental Sciences and Development, North-West University, Private Bag X6001, Potchefstroom,
2520, South Africa, 3 Department of Plant Pathology, University of Stellenbosch, Private Bag X1,
Matieland, 7602, South Africa
E-mail: FlettB@arc.agric.za
Fusarium verticillioides causes Fusarium ear rot (FER) and produces fumonisin
mycotoxins in maize. The feeding habits of stem borers have been associated
with an increase in the incidence and severity of Fusarium ear rot in maize.
Insecticidal proteins synthesised in transgenic (Bt) maize are toxic to stem borer
larvae and have been found to reduce FER as well as fumonisin production in the
USA. In this study, the effect of the B. fusca x F. verticillioides interaction on FER
and fumonisin production was investigated in a transgenic hybrid (PAN6236B)
which expressed the MON810 Bt event, and in its non-transgenic isohybrid
(PAN6126). Treatments on PAN6236B and PAN6126 included a F. verticillioides
(MRC 826) spore suspension injected into the silk channel at the blister stage, B.
fusca infestation into the plant whorl at the 12-13 th leaf stage, and both F.
verticillioides inoculation and B. fusca infestation. Control treatments which were
neither inoculated with F. verticillioides nor infested with B. fusca were included.
All treatments had six replicates, and the experiment was repeated over three
seasons. FER was visually rated and the B. fusca damage measured on the ears
after harvest. Fumonisins were quantified using HPLC. Results indicated that the
B. fusca x F. verticillioides interaction significantly increased FER in the nontransgenic
hybrid only, but did not significantly increase fumonisin production in
both hybrids, suggesting that B. fusca is possibly a vector of F. verticillioides.
There was a significant correlation (r = 0.25; P < 0.05, n = 141) between FER and
fumonisin production in the non-transgenic hybrid, while in the transgenic hybrid
the correlation was non-significant, indicating that transgenic hybrids can have
high fumonisin levels without visible FER symptoms. In conclusion, this study
showed that B. fusca damage to maize ears increases FER, but it has no effect
on fumonisin production.
Keywords: Fusarium, fumonisins, stalkborer, Bt maize
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