Submitted to: Multicrop Aflatoxin and Fumonisin Elimination and Fungal Genomics Workshop-The Peanut Foundation
Publication Type: Proceedings
Publication Acceptance Date: 9/30/2007
Publication Date: 11/1/2007
Citation: Ni, X., Krakowsky, M.D., Buntin, G., Lee, R., Brown, S.L. 2007. Natural distribution patterns of aflatoxin contamination and ear-feeding insect damage in pre-harvest corn: Summary of two-year data. In: Proceedings of the Multi-crop Aflatoxin and Fumonisin Elimination and Fungal Genomics Workshop, October 22-24, 2007, Atlanta, GA. p. 125.
Interpretive Summary: not required
Technical Abstract: Natural distribution patterns of ear-feeding insect damage and aflatoxin levels were examined in 2005 and 2006. A pre-harvest corn field (1/6 hectare) was sampled according to an 8x8 m grid each year. The husk coverage and insect damage were assessed in the field. Insect damage assessment included the corn earworm, Helicoverpa zea (Boddie), the maize weevil, Sitophilus zeamais Motschulsky, as well as the brown, Euschistus servus (Say), and southern green stink bug, Nezara virdula (L.). The top ears from five plants were collected at each grid point in the field when the kernel moisture was at 12% for aflatoxin quantification. The aflatoxin levels in 2005 were positively correlated to the number of the maize weevils (r = 0.3, P = 0.002, n = 92), but not to either corn earworm or stink bug damage, or husk coverage (P-values > 0.05). In contrast, the data collected in 2006 showed that aflatoxin levels in corn samples were positively correlated to both maize weevil number (r = 0.46, P =0.0001, n = 76) and percentage of stink bug-damaged kernels (r = 0.36, P = 0.0012, n = 76), but not to other indices (i.e., corn earworm damage or husk coverage) (P-values > 0.05). The mean aflatoxin levels were not different F = 0.74, df =1, 166, P = 0.3917) between 2005 (33.78 ppb, n = 92) and 2006 (25.51 ppb, n = 76). The roles of insect feeding and other environmental factors on aflatoxin and other mycotoxin accumulations in pre-harvest corn are also discussed.