Bollgard II cotton is in the ground on farms across the Cotton Belt. The technology-packed commodity received registration late last year, and limited quantities of Monsanto's Bollgard II seed were commercially available for this planting season.
Several cotton varieties were available with the genetic ability to express Cry1Ac and Cry2Ab proteins — toxins naturally produced by a bacterium, Bacillus thuringiensis (Bt), that infect caterpillar insects.
Dow AgroSciences has chosen WideStrike as the brand name for its cotton with the dual protein strategy — a combination of the Cry1F and Cry1Ac proteins of Bt. WideStrike is still in the development and testing stage, but it is on track for regulatory approval and commercial introduction in 2004.
Syngenta Crop Protection expects to market a transgenic Bt cotton called Vip Cotton in 2004 or 2005. Vip stands for vegetative insecticidal protein. This technology differs from the other Bt cottons in that it uses exotoxins instead of currently used endotoxins.
The Vip protein is an exotoxin derived from the same Bt bacterium, but the protein is structurally and functionally different than Bt endotoxins, making Vip Cotton an additional choice for improved “in-plant” caterpillar control.
These second-generation Bt cottons have the potential to enhance control of tobacco budworms, bollworms, and many other lepidopterous pests. However, just as with original or first-generation Bt cotton, there will be no suppression of sucking pests in second-generation Bt cotton — there will be bugs.
The importance of knowing how to manage sucking pests in this new generation Bt cotton will be greatly increased. Why will sucking pests be more important in second-generation Bt cotton than they are today?
The reasons are simply extensions of why bugs became more important in current first-generation Bt cotton. All of the factors are involved with one central idea — reduced use of broad-spectrum insecticides for major pest groups and reduced coincidental and incidental suppression of “secondary” pest groups.
For example, one major insecticide input into cotton systems is constantly being reduced — control of the boll weevil. Eradication of the boll weevil is steadily progressing over much of the Cotton Belt, and broad-spectrum insecticide inputs for boll weevil continue to dramatically decline with eradication.
Another insecticide reduction will occur with the pyrethroid insecticides that have provided supplemental control of bollworms in first-generation Bt cotton for seven years now.
If you think pyrethroid use for caterpillar control declined with Bollgard cotton, just wait until producers take a look at Bollgard II this season. Caterpillar control will not become a thing of the past (because insects will always find a way, eventually), but it will not be the focus of insect management efforts in second-generation Bt cotton.
Another reduction in broad-spectrum insecticide use that has been happening over time deals with target specificity. Insecticides for cotton insects in recent years have “gone soft.” There was, and still is, a trend toward rapid adoption/registration of selective or target-specific chemistries. Because these insecticides often target caterpillars, they have little or no activity on bug pests such as plant bugs and stinkbugs.
All of these examples of reduced broad-spectrum insecticide use illustrate how plant bugs and stinkbugs have and will continue to benefit from the direction we are headed with cotton insect control.
Furthermore, broad-spectrum insecticides that do have good activity on plant bugs and stinkbugs are seemingly subjected to constant review, regulation, and cancellation. It is really a shame that that process is not keeping up with technological advances and resulting shifts in the insect pest spectrum and, most importantly, the needs of the backbone of our country that is agriculture.
I guess the take-home message is pretty clear. Watch out for bugs in your second-generation Bt cotton — REALLY watch out. Consult your state's recommendations for identifying and managing plant bugs and stinkbugs, and don't be “bugged” this season.
Jeremy Greene is a entomologist with the University of Arkansas Cooperative Extension Service, Southeast Research and Extension Center, Monticello, Ark. (870-460-1091 or [email protected] ).