Submitted to: Aflatoxin Elimination Workshop Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 10/15/2003
Publication Date: 2/18/2004
Citation: Dowd, P.F., Barnett, R.J., Bartelt, R.J., Beck, J.J., Berhow, M.A., Boston, R.S., Duvick, J.P., Johnson, E.T., Lagrimini, L.M., Molid, G., White, D. 2004. Insect management for reduction of mycotoxins FY 2003 report. Aflatoxin Elimination Workshop Proceedings. p. 13-14. Interpretive Summary:
Technical Abstract: Predictive Monitoring: A sampling technique was developed to augment predictions made by a computer program used to forecast mycotoxin presence in Midwest corn. Samples of different tissues taken from corn plants during 2000-2003, and analyzed using PCR, indicated material that accumulated in leaf axils (primarily anthers and pollen) was a good source of material to detect the presence of Fusarium fungi potentially involved in mycotoxin production. There was considerable variability from field to field and year to year. In both 2002 and 2003, F. proliferatum and F. verticillioides were relatively uncommon compared to F. subglutinans. Visible moldiness of leaf axil material was a relatively good indicator of the presence of Fusarium spp. fungi. Conversion of the predictive computer program from a DOS to Windows version has been completed. An additional portion to help farmers make economic decisions on treating for pests or early harvest is under development. Values predicted for fumonisin for 2002 (a relatively hot, wet year during the growing season in Central Illinois) were relatively low compared to actual field values, but collected data was used to adjust the program without adversely affected predictions for prior years, which had been fairly accurate. Although low levels of aflatoxin were predicted for the Central Illinois area, no aflatoxin was detected in fields surveyed. However, some grain loads were rejected by elevators in the area near the highest predicted values. When weather data from the areas where high levels of aflatoxin occurred in 2002 were used in the program, in predictions of over 100 ppm resulted in some cases. In 2003, no aflatoxin was predicted, and fumonisin levels were predicted to be low in general (< 2 ppm). Analysis is pending. In the third year of a study on trap types and pheromone sources in Bt vs. non-Bt sweet corn, a commercial source of traps were found to be as effective as prior traps developed by USDA; and a commercial source of the dusky sap beetle pheromone was found to be as effective as USDA produced material. Thus, effective commercial materials are now completely available for monitoring the dusky sap beetle (which is also associated with mycotoxin problems). Insect Resistance/Plant Transformation: Lines of tobacco that produce an activated form of the maize RIP have now had plants identified that appear to have the gene in homozygous state. This will allow crosses with other plants having different resistance genes (tobacco anionic peroxidase) to determine gene combination effects. Plant allelochemicals responsible for insect resistance in silks of Tex6 are still being determined, as are insect resistance chemicals produced in high peroxidase plants. Constructs with maize peroxidase clones potentially involved in fungal resistance based on pIs similar to isozymes associated with resistant material have been produced and await expression in maize lines for evaluation. A construct incorporating a gene coding for an analog of a novel protein previously demonstrated to be toxic to caterpillars is being introduced into maize for evaluation. Plants containing a mutated regulatory gene introduced transgenically that allows for accumulation of phenylpropanoids and other resistance materials appears to be more resistant to some insect feeding, such as by fall armyworms, but has lower productivity than wild-type plants. Floral tissue from a mutant plant line was found to cause high mortality to cabbage loopers and corn earworms, and to significantly reduce feeding and growth of fall armyworms. Responsible bioactive compounts from the floral tissue are being evaluated. Constructs produced from different transposon sources designed to increase precision of gene insertion have been produced and are being evaluated.