GM crops improve PH biodiversity

GENETICALLY-modified (GM) crops help improve biodiversity, the chief biotechnologist of the Department of Agriculture (DA) argues.

Dr. Saturnina C. Halos, chairwoman of DA’s Biotechnology Advisory Team (BAT), says developments in areas planted to GM crops in the Philippines attest to the beneficial impact of these crops.

“Biodiversity in the context of GM crops covers variations observed within the crop, of organisms within the farm and of organisms in the environment where the farm is,” she said.

Halos noted that GM crop areas have expanded to 148 million hectares in 29 countries and the cultivation of these crops is covered by the Cartagena Protocol on Biosafety of the Convention on Biological Diversity.

She cited the Carpenter study last year to show that “over-all currently commercialized GM crops have reduced the impacts of agriculture on biodiversity, through enhanced adoption of conservation tillage practices, reduction of insecticide use and use of more environmentally benign herbicides and increasing yields to alleviate pressure to convert additional land into agricultural use.”

Only four GM crops are planted in 148 million hectares - soybean, corn, canola and cotton with 2 transgenic traits – insect resistance and herbicide tolerance (HT.)

“Insect resistance is due to the Bacillus thuringienses (Bt) gene and herbicide tolerance to a variant epsps gene transferred to the plant. The Bt gene produces a protein toxic to lepidopterans (moths and butterflies) or coleopterans (beetles). Herbicide tolerance is ability to survive glyphosate, a herbicide that degrades rapidly in the environment. The genes may be found singly or in combination in the plant. These crops have been much studied in the past 15 years,” Halos stressed.

Since the Bt corn cultivated in the Philippines has herbicide tolerance, it follows that minimum tillage is required, meaning the soil is not cultivated as much as in conventional farming. GM crops with herbicide tolerance are planted in  million hectares worldwide.

“With herbicide tolerant crops in minimally cultivated soils, the weeds are allowed to grow then sprayed with glyphosate, killing the weeds and leaving the herbicide tolerant GM crop to grow. This means the soil organisms are not disturbed, hence their diversity is maintained,” Halos noted.

She said weed populations may change since glyphosate kills the weeds and the seeds below the ground will eventually sprout and get killed.

“Studies showed that some HT crops retain weed diversity and others have reduced weed diversity. Local studies by our own Bureau of Plant Industry (BPI) show that weed diversity in HT corn fields and non-HT corn fields are the same.  Other factors other than the HT trait that affects the extent of weed diversity in GM crop fields,” Halos revealed.

The Bt protein product, being insecticidal, has been subjected to serious questions since it may act in the same fashion as synthetic insecticides.

“Is the Bt protein specific enough to act benign on non-target organisms and kill only the target organisms? Limited laboratory tests show that other non-target Lepidoptera succumbs to Bt proteins intended for Lepidoteran pests. A very good example was the laboratory test killing of Monarch butterfly larvae. However, several field studies have shown that the laboratory exposure does not happen in the field and that Monarch butterfly are more in abundance in Bt corn fields than in conventional fields that are sprayed with insecticides,” Halos reported.

“Similarly, other non-target organisms including friendly arthropods thrive better in Bt crop fields, a conclusion reached by other scientists, including Filipino scientists and regulators of the BPI. Thus, Bt crops promote biodiversity,” she declared.

The most direct negative impact of agriculture to biodiversity is from loss of natural habitat due to the conversion of natural ecosystems into agricultural land, Halos argued.

However, this impact can be nullified by increasing yields per unit area, making it possible to grow more food in less land.

“A major reason why GM crops have been expanding is because farmers are making more money from getting higher yields per unit area. Globally, GM soybean yields increased 29.8 percent, and this additional yield would have required an additional 5.9 million hectares using conventional varieties, GM corn yields increased by 7.6 percent, which would have required 3.0 million hectares more, and GM cotton by 19.8 percent, which would have required 2.5 million hectares of land. Planting GM crops can thus reduce the pressure of converting natural ecosystems to agriculture and thereby promote biodiversity. Over-all, studies in the past 15 years show that GM crops promote biodiversity,” Halos concluded.

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