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United States Department of Agriculture

Agricultural Research Service

Research Project: Genetic Improvement of Maize and Sorghum for Resistance to Biotic Stress

Location: Crop Genetics and Breeding Research

Title: Evaluation of fall armyworm resistance in maize germplasm lines using visual leaf injury rating and predator survey

Authors
item Ni, Xinzhi
item Xu, Wenwei -
item Blanco, Michael
item Williams, William

Submitted to: Insect Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: November 27, 2013
Publication Date: N/A

Interpretive Summary: The long-term goal of our research is to develop corn germplasm lines that are resistant to both whorl- and ear-feeding insects. After examining ear-colonizing pest resistance, 20 corn germplasm lines from the USDA-ARS germplasm enhancement of Maize (GEM) Program were evaluated for whorl-feeding fall armyworm (FAW) under the field conditions in 2009 and 2010. The FAW injury was rated on 7 and 14 days after the manual infestation of the corn plants with newly-hatched FAW larvae. In addition, the diversity and abundance of beneficial arthropods (i.e., predatory insects and spiders) in each experimental plot were also recorded 7 d after the FAW infestation. Of the 20 germplasm lines examined, three tropical corn germplasm lines originated from Uruguay, Cuba, and Thailand were identified as the best FAW-resistant germplasm lines. The abundance and diversity of the predators were greater in 2010 than in 2009, which might have caused the low FAW injury ratings on all lines examined in 2010. The two-year data showed that the FAW injury ratings were negatively correlated to the predator abundance and diversity. The findings suggested that tropical germplasm lines are an important source of native resistance to the FAW and the corn earworm. At the same time, the maize genotype × environment interaction, such as, predator attractiveness, and varying weather conditions from year to year, should be included to accurately assess maize germplasm resistance to insects and diseases under field conditions.

Technical Abstract: After examining ear-colonizing pest resistance, 20 maize lines from the USDA-ARS germplasm enhancement of Maize (GEM) Program were evaluated for whorl-feeding fall armyworm (FAW) (Spodoptera frugiperda) resistance using four maize inbred lines as the resistant and susceptible controls. Both FAW injury ratings at 7- and 14-d after infestation, and predator abundance and diversity at whorl stage (V6-V8) were recorded in 2009 and 2010. The survey of the diversity and abundance of predators in each experimental plot were conducted 7 d after the FAW infestation. Of the 20 germplasm lines examined, three of them (i.e., entries 9, 15, and 19 that were derived from tropical maize germplasm lines originated from Uruguay, Cuba, and Thailand, respectively) were identified as the best FAW-resistant germplasm lines using the leaf injury ratings and predator survey data. In addition, the abundance and diversity of the predators were greater in 2010 than in 2009, which might have caused the low level of the FAW injury rating on all lines examined in 2010. The two-year data showed that the FAW injury ratings were negatively correlated to the predator abundance and diversity. The findings suggested that tropical germplasm is an important source of native resistance to the FAW and the corn earworm. At the same time, the maize genotype × environment interaction (e.g., predator attractiveness, and varying weather conditions) should be included in the multiple-year evaluation of maize germplasm resistance to insects and diseases under field conditions.

Last Modified: 7/25/2014
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