The advent of Bollgard II has North Carolina State University entomologist J.R. Bradley, Monsanto and other researchers wondering whether refuges planted in compliance with federal insect resistance management requirements delay resistance.
The 2005 season will give researchers two years of data on the issue and likely will lead to a request to the Environmental Protection Agency.
"I know of no law or legal basis for IRM," Bradley says. "While the goal to delay resistance development is honorable, a wealth of information has been obtained that suggests the refuge requirement is inappropriate for the Southeast."
Monsanto representatives also suspect refuge management is superfluous with the advent of Bollgard II.
However, Monsanto representive Jennifer Garrett says: "We continue to support the current refuge requirements, however we are continuing to monitor and collect data both in the 2004 and 2005 growing seasons for Bollgard II. We will only be requesting changes if we compile a sufficient amount of scientific data to support changes."
Bradley doubted the scientific validity of insect resistance management even before Bollgard II was introduced. With the introduction of a second mode of action, his doubts increased.
Bradley is gathering data again this year with a goal of filing a request with the U.S. Environmental Protection Agency requesting removal of refuge requirements for Bt cotton.
The problem, as Bradley sees it, has many layers:
- Entomologists donâ€™t have a good track record for predicting the time of resistance, particularly when a new pest control technology is at issue.
- No "untreated check" exists to determine if refuge requirements work.
- New technologies on the horizon make IRM irrelevant.
- Weed and non-cotton cultivated hosts, such as peanuts and tobacco, also provide refuge, possibly enough to alleviate the need for planted cotton refuge.
- Cotton refuges donâ€™t produce enough moths â€“ and donâ€™t produce them synchronously with those that survive in Bt cotton.
- Many growers donâ€™t strictly comply with refuge requirements, making them moot in many instances.
The requirements are that a grower who plants Bt cotton must also plant conventional cotton, either 20% if he intends to treat for insects or 5% if he doesnâ€™t spray the conventional field with insecticide.
"In my area," Bradley says, "many growers plant a 5% refuge and then spray the heck out of it."
Monsantoâ€™s statistics are a bit better - but theyâ€™re based on a survey rather than Bradleyâ€™s on-the-ground experience. According to their compliance survey, Garrett says, grower compliance with refuge requirements still is 90% or better.