Nebraska-Brazil Study New and Old Corn Insect Pests

Corn earworm and fall armyworm in lab studies. Photo: UNL CropWatch

US farmers may not be very familiar with the Old World bollworm, Helicoverpa armigera (Lepidoptera: Noctuidae). This species is native to Asia, Europe, Africa, and Australasia where it is a significant agricultural pest, causing billions of US dollars in damages annually due to yield losses and insecticide application. The Old World bollworm, which feeds on corn ears, is now causing damage to crops in the Western Hemisphere.

For the last five years the species has been a problem for Brazilian crops, adding to the economic damage already caused by other noctuids such as the fall armyworm (Spodoptera frugiperda) and corn earworm (Helicoverpazea). Unfortunately, this pest has impressive migratory abilities and has been increasing its range since its first detection in Brazil. While Old World bollworm moths have now been found on the western coast of Florida, the pest has not become established yet in North America.

With the introduction of this pest looming for North America, it is important to understand how it might affect US crop production. One factor affecting its status will be how it interacts with pests already established in the United States. Pest species that rely on the same food source (corn ears) will be in competition with each other and may engage in predation or cannibalism.

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From a bioecological standpoint Old World bollworm is similar to several pests already active in US corn, including the corn earworm and fall armyworm, both of which present cannibalistic and predatory behavior. In Brazil, these species are already cohabiting in diverse agricultural crops, as well as sharing the same feeding site.

Therefore researchers from the University of Nebraska-Lincoln in partnership with two Brazilian researchers, Edson Luis Baldin from the São Paulo State University and Silvana V. de Paula Moraes (EMBRAPA), today at the University of Florida, are investigating interactions of the main corn ear-feeding pests in South and North America (Figures 1-4).

The introduction of the Old World bollworm in Brazil (probably in 2008, with identification in 2012-13) led to a drastic change in pest management in crops such as corn, soybean, and cotton. As the Old World bollworm becomes prevalent in Western hemisphere crops, it can be assumed that existing pest populations may change their population dynamics.

When this occurs, the tools used to manage agricultural pests (integrated pest management and insect resistance management) will need to be improved. It is our responsibility to better understand these interactions to properly manage these economically disruptive species in crops.

Laboratory research on corn ear pests

Figure 1. Corn earworm and fall armyworm in laboratory studies to evaluate behavior patterns in the presence and absence of food.

Laboratory research on corn ear pests

Figure 2. Researchers are studying the interaction among species on non-Bt corn ears to determine the larval survival.

Laboratory research on corn ear pests

Figure 3. Interaction among species on corn under field conditions to evaluate cannibalism/predation rates.

Laboratory research on corn ear pests

Figure 4. Fall armyworm and corn earworm on non-Bt corn.


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