Fungal Species Composition in Maize Stalks in Relation to European Corn Borer Injury and Transgenic Insect Protection

Area of Science:

• Plant Pathology
• Entomology
• Agricultural Science

Background:

• Maize stalk rot is a complex of fungal diseases.
• European corn borer (ECB) larvae create entry wounds and vector stalk rot pathogens.
• Bacillus thuringiensis (Bt) maize reduces ECB injury, potentially altering fungal pathogen dynamics.

Purpose of the Study:

• To compare the fungal species composition and diversity in Bt and non-Bt maize hybrids.
• To investigate the impact of reduced ECB injury on the maize stalk rot complex.

Main Methods:

• Field experiments conducted over three years (1998-2000).
• Comparison of five Bt maize hybrid types and their near-isogenic non-Bt counterparts.
• Manual and natural ECB infestation, followed by fungal culturing from stalk tissues.

Main Results:

• Fungal species were isolated from most maize stalks, regardless of disease symptoms.
• Fusarium species (F. verticillioides, F. proliferatum, F. subglutinans) were less prevalent in Bt hybrids compared to non-Bt hybrids.
• Gibberella zeae was more prevalent in some Bt hybrids than non-Bt counterparts.
• Fusarium verticillioides was associated with ECB injury, while G. zeae and C. graminicola were not.
• Overall fungal species diversity was lower in some Bt hybrids.

Conclusions:

• Bt maize hybrids altered the species composition and diversity of the stalk rot complex compared to non-Bt hybrids.
• ECB injury significantly influences the fungal species colonizing maize stalks.
• The ecological implications of altered fungal communities in Bt maize require further investigation.