European corn borer (ECB) numbers, as well as damage attributed to the insect, were at record lows across the U.S. Corn Belt in 2004. Given the resulting low overwintering populations, early-season threats from this pest are predicted to be relatively light. However, experts encourage growers to prepare for potential pressure from second-generation corn borer in 2005.

Utilizing insect-resistant hybrids with Bt technology, such as Herculex¹ I insect protection, is an effective risk management tool against first- and second-generation ECB pressure. Entomologists agree investing in Bt technology can prevent yield loss, as well as limit the need for scouting and potential insecticide treatments throughout the growing season.

"It is very difficult to accurately predict if an insect such as ECB will reach its reproductive potential," says John Obermeyer, Extension entomologist at Purdue University. "More than any other factor, environmental conditions during the growing season will determine whether this insect becomes a serious threat in 2005."

Obermeyer explains that wet spring weather, similar to what the Corn Belt experienced in 2004, has an adverse effect on the mating and egg-laying of ECB - which results in low overwintering populations. However, with prime environmental conditions for egg hatch, growers could still see heavy second-generation ECB infestation levels. Under optimal conditions, each female corn borer can lay 400 eggs across many locations, quickly populating a previously non-populated area.

Entomologists caution growers

Although overwintering numbers are at a 5-year low, Obermeyer encourages producers to calculate the economic risks before making a decision not to plant a Bt hybrid.

"We've been studying the economic impact of this pest for years," says Obermeyer. "Even with the low amount of ECB damage in 2004, the state average remains at a $5 to $6 loss per acre. The investment in insect-resistant hybrids is about or a little less than that."

Kevin Steffey, Extension entomologist at the University of Illinois, agrees that first-generation ECB pressure probably won't be high, but the second generation is unpredictable.

"The fact is that densities could explode," says Steffey. "Insects are notorious for that - going from one to thousands in just two generations."

Illinois also experienced extremely low ECB pressure throughout the growing season in 2004. The University of Illinois' annual ECB survey reports the average percent infestation of second-generation ECB per 100 plants was only 17.1 percent. However, Steffey cautions growers to examine long-term ECB trends in the area where they'll be planting.

"Our fall survey does no more than give a snapshot of ECB pressure from the past season and where we'll start the next growing season," says Steffey. "Planting dates, weather patterns, storms, extreme weather (wet or dry), natural enemies - all effect ECB pressure. Depending upon the combination of these factors, ECB populations can go either up or down, whether they get off to a relatively slow start or not."

Murt McLeod, entomologist and agronomy research manager for Pioneer Hi-Bred International, Inc., also cautions growers not to use overwintering populations as the only factor in determining whether to use a Bt technology for the next year.

"Too many environmental factors influence ECB pressure to base decisions strictly on overwintering populations," says McLeod. "We've had a couple of years of low pressure. But be very careful in using that as an indication of what's to come in 2005. Corn borer pressures are very hard to predict. Low ECB pressures in 2004 has absolutely nothing to do with 2005."

Options for managing risks

Pioneer® brand corn hybrids offer producers several choices of Bt technology for the upcoming planting season. Hybrids containing the Herculex I insect protection offer the industry's broadest spectrum of in-plant insect control. The Herculex I trait provides excellent control of European (first and second brood) and southwestern corn borer, as well as fall armyworm. It also offers moderate resistance to corn earworm and is the only Bt gene offering in-plant resistance to black cutworm and western bean cutworm.

Pioneer also offers hybrids containing the YieldGard² Corn Borer gene for season-long resistance to European and southwestern corn borer, along with intermediate resistance to corn earworm and above-average resistance to fall armyworm.

Pioneer Hi-Bred International, Inc., a subsidiary of DuPont, is the world's leading source of customized solutions for farmers, livestock producers and grain and oilseed processors. With headquarters in Des Moines, Iowa, Pioneer provides access to advanced plant genetics, crop protection solutions and quality crop systems to customers in nearly 70 countries. DuPont is a science company. Founded in 1802, DuPont puts science to work by creating sustainable solutions essential to a better, safer, healthier life for people everywhere. Operating in more than 70 countries, DuPont offers a wide range of innovative products and services for markets including agriculture, nutrition, electronics, communications, safety and protection, home and construction, transportation and apparel.

¹ Herculex is a trademark of Dow AgroSciences LLC. Herculex I insect protection by Dow AgroSciences and Pioneer Hi-Bred.