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United States Department of Agriculture

Agricultural Research Service

Research Project: GENETIC IMPROVEMENT OF MAIZE AND PEARL MILLET FOR RESISTANCE TO INSECTS AND AFLATOXIN Title: Evaluation of spatial and temporal patterns of insect damage and aflatoxin level in the pre-harvest corn fields to improve management tactics

Authors
item Ni, Xinzhi
item Wilson, Jeffrey
item Toews, Michael -
item Buntin, G. David -
item Li, Xin -
item Lei, Zhongren -
item He, Kanglai -
item Xu, Wenwei -
item Li, Xianchun -
item Huffaker, Alisa
item Schmelz, Eric

Submitted to: Insect Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: March 26, 2012
Publication Date: N/A

Interpretive Summary: Both crop genetics and ecology are important in pest management in a crop field. Although much progress in crop genetics has been made, distribution patterns of insect damage in relation to aflatoxin contamination in a corn field are still not well understood. Thus, we examined the distribution patterns of cob and kernel feeding insect damage, and aflatoxin levels with two samplings at pre-harvest in 2008 and 2009. The ear/kernel feeding damage and maize weevil populations were assessed across the corn fields. Grid-sampling data showed a field edge effect in both insect damage and aflatoxin contamination in both years. Maize weevil infestations had an aggregated distribution more frequently than either corn earworm or stink bug damage in both years. The frequency of detecting aggregated distribution for aflatoxin level was less than any of the insect damage assessments. Stink bug damage and maize weevil numbers were more closely associated with aflatoxin level than was corn earworm damage. In addition, maize weevil populations were associated between the two sampling times, while other parameters varied in the two years. The strong field edge effect and its ramifications in the management of insect damage and aflatoxin contamination are also discussed.

Technical Abstract: Spatial and temporal patterns of insect damage in relation to aflatoxin contamination in a corn field with plants of uniform genetic background are not well understood. After previous examination of spatial patterns of insect damage and aflatoxin in pre-harvest corn fields, we examined spatial and temporal patterns of cob and kernel feeding insect damage, and aflatoxin level with two samplings at pre-harvest in 2008 and 2009. The feeding damage by each of the ear/kernel-feeding insects (i.e., corn earworm/fall armyworm damage on the silk/cob, and discoloration of corn kernels by stink bugs), and maize weevil population were assessed at each grid point with five ears. Sampling data showed a field edge effect in both insect damage and aflatoxin contamination in both years. Maize weevils tended toward an aggregated distribution more frequently than either corn earworm or stink bug damage in both years. The frequency of detecting aggregated distribution for aflatoxin level was less than any of the insect damage assessments. Stink bug damage and maize weevil number were more closely associated with aflatoxin level than was corn earworm damage. In addition, the indices of spatial-temporal association (') demonstrated that the number of maize weevils was associated between the first and fourth sampling weeks in both years on all fields. In 2009, corn earworm damage between the first and fourth week from the field on the Belflower Farm, and aflatoxin level and corn earworm damage from the field on the Lang Farm were dissociated.

Last Modified: 12/20/2014
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