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: Giant anteaters kill two hunters in Brazil

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

Giant anteaters kill two hunters in Brazil

Jul 26, 2014

Giant anteaters in Brazil have killed two hunters in separate incidents, raising concerns about the animals' loss of habitat and the growing risk of dangerous encounters with people, researchers said.

Study indicates large raptors in Africa used for bushmeat

Jul 24, 2014

Bushmeat, the use of native animal species for food or commercial food sale, has been heavily documented to be a significant factor in the decline of many species of primates and other mammals. However, a new study indicates ...

Noise pollution impacts fish species differently

Jul 24, 2014

Acoustic disturbance has different effects on different species of fish, according to a new study from the Universities of Bristol and Exeter which tested fish anti-predator behaviour.

User comments : 0