Insect resistance to Bt crops can be predicted, monitored and managed

Nov 23, 2009

Since 1996, crop plants genetically modified to produce bacterial proteins that are toxic to certain insects, yet safe for people, have been planted on more than 200 million hectares worldwide. The popularity of these Bt crops, named after the bacterium Bacillus thuringiensis, comes from their ability to kill some major pests, allowing farmers to save money and lessen environmental impacts by reducing insecticide sprays.

However, since can evolve resistance to toxins, strategies must be implemented to ensure that Bt crops remain effective. A new study published in the December issue of Journal of Economic Entomology entitled "Field-Evolved Insect Resistance to Bt Crops: Definition, Theory, and Data" (http://www.entsoc.org/btcrops.pdf) analyzes insect resistance data from five continents, as reported in 41 studies, and concludes that existing theories and strategies can be used to predict, monitor, and manage insect resistance to Bt crops.

According to lead author Dr. Bruce E. Tabashnik, "Resistance is not something to be afraid of, but something that we expect and can manage if we understand it. Dozens of studies monitoring how pests have responded to Bt crops have created a treasure trove of data showing that resistance has emerged in a few pest populations, but not in most others. By systematically analyzing the extensive data, we can learn what accelerates resistance and what delays it. With this knowledge, we can more effectively predict and thwart ."

Among the authors' conclusions are:

  • The refuge strategy (growing non-Bt crops near the Bt crops) can slow the evolution of insect resistance by increasing the chances of resistant insects mating with non-resistant ones, resulting in non-resistant offspring.
  • Crops that are "pyramided" to incorporate two or more Bt toxins are more effective at controlling insect resistance when they are used independently from crops that contain only one Bt toxin.
  • Resistance monitoring can be especially effective when insects collected from the field include survivors from Bt crops.
  • DNA screening can complement traditional methods for monitoring resistance, such as exposing insects to toxins in the lab.
  • Despite a few documented cases of field-evolved resistance to the Bt toxins in transgenic crops, most insect pest populations are still susceptible.
With Bt crop acreage increasing worldwide, incorporating enhanced understanding of observed patterns of field-evolved resistance into future resistance management strategies can help to minimize the drawbacks and maximize the benefits of current and future generations of transgenic crops.

Source: Entomological Society of America (news : web)

Explore further: Genetically tracking farmed fish escaping into the wild

add to favorites email to friend print save as pdf

Related Stories

GM crops protect neighbors from pests

Sep 18, 2008

A study in northern China indicates that genetically modified cotton, altered to express the insecticide, Bt, not only reduces pest populations among those crops, but also reduces pests among other nearby crops that have ...

New designer toxins kill Bt-resistant insect pests

Nov 01, 2007

A new way to combat resistant pests stems from discovering how the widely used natural insecticide Bt kills insects. Figuring out how Bt toxins punch holes in the cells of an insect's gut was the key to designing ...

Insecticide combo delivers knockout punch

Mar 12, 2008

A cocktail of insecticides containing a plant protein and a common insecticide may be more lethal to crop pests than either ingredient used alone, according to biologists. The one-two punch also inhibits the insects' growth ...

Recommended for you

Genetically tracking farmed fish escaping into the wild

19 hours ago

European sea product consumption is on the rise. With overfishing being a threat to the natural balance of the ocean, the alternative is to turn to aquaculture, the industrial production of fish and seafood. ...

France fights back Asian hornet invader

22 hours ago

They slipped into southwest France 10 years ago in a pottery shipment from China and have since invaded more than half the country, which is fighting back with drones, poisoned rods and even chickens.

Tide turns for shark fin in China

22 hours ago

A sprawling market floor in Guangzhou was once a prime location for shark fin, one of China's most expensive delicacies. But now it lies deserted, thanks to a ban from official banquet tables and a celebrity-driven ...

Manatees could lose their endangered species status

Aug 19, 2014

About 2,500 manatees have perished in Florida over the last four years, heightening tension between conservationists and property owners as federal officials prepare to decide whether to down-list the creature to threatened ...

User comments : 0