More pests resistant to GMO crops—study



PARIS—More pest species are becoming resistant to the most popular type of genetically-modified, insect-repellent crops, but not in areas where farmers follow expert advice, a study said on Monday.

The paper delves into a key aspect of so-called Bt corn and cotton — plants that carry a gene to make them exude a bacterium called Bacillus thuringiensis, which is toxic to insects.

Publishing in the journal Nature Biotechnology, US and French researchers analyzed the findings of 77 studies from eight countries on five continents that reported on data from field monitors.

Of 13 major pest species examined, five were resistant by 2011, compared with only one in 2005, they found. The benchmark was resistance among more than 50 percent of insects in a location.

Of the five species, three were cotton pests and two were corn pests.

Three of the five cases of resistance were in the United States, which accounts for roughly half of Bt crop plantings, while the others were in South Africa and India.

The authors said they picked up a case of early resistance, with less than 50 percent of insects, in yet another US cotton pest.

And there were “early warning” signs (one percent resistance or less) from four other cotton or corn pests in China, the United States and the Philippines.

The scientists found big differences in the speed at which Bt resistance developed.

In one case, it took just two years for the first signs to emerge; in others, the Bt crops remained as effective in 2011 as they were 15 years earlier.

What made the difference was whether farmers set aside sufficient “refuges” of land for non-BT crops, said the study’s authors.

The idea behind such refuges comes from evolutionary biology.

The genes that confer resistance are recessive, meaning that insects can survive on Bt plants only if they have two copies of a resistance gene — one from each parent.

Planting refuges near Bt crops reduces the chances of two resistant insects mating and conferring the double gene to their offspring.

“Computer models showed that refuges should be good for delaying resistance,” study co-author Yves Carriere, an entomologist at the University of Arizona at Tucson, said in a press release.

Practical evidence of this is shown in the case of a cotton-munching pest called the pink bollworm, said his colleague, Bruce Tabashnik.

Bt crops in the southwestern United States, where growers work closely with scientists to devise a refuge strategy, do not have a resistance problem.

In India, though, local pink bollworms became resistance within six years, simply because farmers did not follow the guidelines or get this support.

The researchers cautioned that resistance to Bt crops was simply a matter of time, as all pests eventually adapt to the threat they face. But refuges were the key to braking it.

“Either take more stringent measures to delay resistance such as requiring larger refuges or this pest will probably evolve resistance quickly,” said Tabashnik.

Farming groups have been furiously debating the value of refuges, and in recent years the US Environmental Protection Agency (EPA) relaxed its refuge-planting requirements.

More than a billion acres (420 million hectares) of land have been planted with Bt crops since the mid-1990s.

In 2011 alone, 66 million hectares (164 million acres) of land was planted with Bt crops.

That year Bt corn accounted for 67 percent of corn planted in the United States and Bt cotton for between 79-95 percent of cotton planted in the US, Australia, China, and India.

Transgenic crops are opposed in Europe and other parts of the world where green activists say they are a potential threat to human health and the environment.

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  • ApoNiLolo

    A lot was said by both pros and cons regarding GMO crops. Unless it is proven by either side their safety or health hazard, IMHO, it is prudent to stick to “natural” farming for the mean time… just to be on the safe side.

    • WeAry_Bat

      Just as there is growing disdain for vegetables grown with pesticides, why would anyone want to eat food intrinsically laced with pesticide, even if natural.

    • kangsongdaeguk

      That would be ideal, but consider long-term planning, population explosion (less land for farming because used for housing, infrastructure, among others), turning to GMO crops is a seemingly good proposition.

      • ApoNiLolo

        Point taken as long as they ironed out every kinks and everybody agrees that GMO crops are safe for human consumption. : )

      • kangsongdaeguk

        Yeah, problem is there are those people (i.e. church people) whose reasoning are to the likes of “don’t interfere with God’s plan for nature”. Duh.

      • ApoNiLolo

        Religious fanatics? What do this people who delve in pseudo-science know? Pwera ang mga taong hindi marunong mag-isip at walang bait sa sarili.

      • kangsongdaeguk

        Indeed. And unfortunately, ang dami ding di masyadong knowledgeable sa aspect na ‘to at basta na lang tanggap ng tanggap sa mga sinasabi ng mga to.

  • alex ca

    cancer ang aabutin nyo sa GMO mga kababayan umiwas kayo……..

  • Apex Illuminati

    maswerte sa ngayon ang may sariling taniman at masipag magtanim kawawa ang wala at mga tamad magtanim ng sarili.

  • calipso_2100

    But of course. Scientists knew there will come a time their GMO crops will become resistant to nothing. Insects evolve fast since they reproduce fast. Heck, the GMO crops are evolving as well and they could be evolving in a way the manufacturers don’t like. Like maybe becoming able to produce seeds that will actually grow (most GMO crops are designed such that their seeds are “infertile” so that farmers will have to buy the “fertile” seeds or seedlings every time they plant).

    Nature has it’s way of balancing things up when one side is gaining an unfair advantage.

  • opinyonlangpo

    What is bad for living organisms is bad for human. This GMO at the end will also cause human mutation, a problem for future mutant generation.

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