environmental iSSUeS

WitH tranSgenic croPS

Presented by… Bhubanananda Adhikari

Ph.D scholar

Dept. of EntomologyO.U.A.T,, Bhubaneswar

Odisha

GMO: Boon or Bane

Long-term exposure to pollen from GM insectresistant maize causes adverse effects on the behaviour (Prasifka et al . , 2007) and survival (Dively et al . , 2004) of the monarch butterfly, America’s most famous butterfly.

Few studies on European butterf l ies have been conducted, but those that have suggest they would suffer from pesticide-producing GM crops (Lang, & Vojtech, E. 2006).

Toxic to harmless non-target species

These studies are all based on one type of toxin, Cry1Ab, present in GM maize variet ies Bt11 and MON810

Toxic to harmless non-target species

• In 1999,  Dr. John Losey, sent a description of the study to the editors of the science journal Nature (Volume 399, 20 May 1999, page 214).

• In Dr. Losey 's s tudy, monarch caterpil lars in a laboratory were fed milkweed leaves that had been dusted with pollen from Bt corn .

• His study found that " … larvae of the monarch butterfly on milkweed leaves dusted with transgenic Bt-corn pollen ate less, grew more slowly, and suffered higher mortali ty than those fed leaves dusted with untransformed corn pollen or leaves without pollen . "

Toxic to harmless non-target species

Toxic to harmless non-target species

• Some people understood the results of the lab study to mean that Bt corn harms monarch caterpillars, but other scientists pointed out that the study may not accurately reflect what would happen in a field of Bt corn. They noted that:

• There were higher amounts of Bt pollen on the milkweed leaves in the lab than there would be found in a field

• In the lab, caterpillars were l imited to eating only leaves covered in corn pollen, whereas in a f ield, caterpillars may be able to avoid pollen-coated leaves.

Toxic to harmless non-target species

• Cry1F, present in the GM maize 1507 is highly l ikely to also be toxic to non-target organisms l ike lepidoptera and coleoptera (Otto and Lang, 2010)

Toxic to harmless non-target species

Toxic to harmless non-target species

Toxic to beneficial insects

Effect of Cry 1 Ab toxin maintained in Green lace wing (Obrist et al . ,2010).

transgenic crops expressing Cry1Ab protein at 5000 ppb may affect food consumption or learning processes and thereby may impact honey bee foraging eff iciency . (Ramirez-Romero et al . ,2008)

Uptake of Cry1Ab toxin by larvae of the green lacewing Chrysoperla carnea (Stephens) tested af ter consuming two Bt maize- fed herbivores (Tetranychus urticae Koch and Spodoptera l i t toralis (Boisduval) by means of an immunological test (ELISA) and the act ivi ty of the Cry1Ab toxin following ingestion by the herbivores.

The activity of Cry1Ab toxin produced by Bt maize to that of purif ied toxin obtained from transformed Escherichia coli , which is recommended to be used in toxicity s tudies. The act iv ity of the toxin was assessed by performing feeding bioassays with larvae of the European corn borer Ostrinia nubilal is

ELISA confirmed the ingestion of Bt toxin by C. carnea larvae when fed with either of the two prey species and feeding bioassays using the target pest showed that the biological activi ty of the Cry1Ab toxin is maintained after ingest ion by both herbivore species.

The purif ied Cry1Ab protein was more toxic to O. nubilal is compared to the plant-derived Cry1Ab toxin when applied at equal concentrations according to ELISA measurements. Possible reasons for these f indings are discussed. (Obrist et al . ,2010)

Toxic to beneficial insects1.To Green Lace wing

Case Study

The goal of study was to assess potential effects of two concentrations of Cry1Ab protein (3 and 5000 ppb) on young adult honey bees.

Experiments evaluated effects of the Cry1Ab on three major l i fe traits of young adult honey bees: (a) survival of honey bees during sub-chronic exposure to Cry1Ab, (b) feeding behaviour, and (c) learning performance using the proboscis extension reflex (PER) procedure. The same effects were also tested using a chemical pesticide, imidacloprid, as positive reference.

Honey bees exposed to 5000 ppb of Cry1Ab had disturbed learning performances. Honey bees continued to respond to a conditioned odour even in the absence of a food reward.

Our results show that transgenic crops expressing Cry1Ab protein at 5000 ppb may affect food consumption or learning processes and thereby may impact honey bee foraging eff iciency . (Ramirez-Romero et al . ,2008)

Toxic to beneficial insects1.To Honeybee

Case Study

A threat to soil ecosystems…

Many Bt crops secrete their toxin from their roots into the soil

Residues left in the f ield contain the active Bt toxin . (Flores et al . , 2005)

The long-term, cumulative effects of growing Bt maize are of concern.

A threat to soil ecosystems…Case Study

A Risk for aquatic life.…

Leaves or grain from Bt maize can enter water courses where the toxin can accumulate in organisms and possibly exert a toxic effect (Douville et al. , 2009)

This demonstrates the complexity of interactions in the natural environment and underlines the shortcomings of the current risk assessment.

A Risk for aquatic life.…

• The purpose of this study was to examine the contamination of cry1 and cry1Ab genes from Bacillus thuringiensis and transgenic corn in feral freshwater mussels collected from sites located in proximity of corn fields.

• In addition, mussels were transplanted for 2 months to a site in the Huron River, upstream to the Richelieu River, which is subject to intensive corn farming.

• Gene sequence analysis confirmed the presence of transgenic corn cry1Ab gene in mussel t issues. In an attempt to explain the presence of the transgene in mussel t issues, heterotrophic bacteria were grown from surface water and sediment samples on agar plates in the Richelieu River in May and August. The transgene was found at two out of six surface water samples and in one sediment sample. (Douville et al. , 2009)

• The study revealed that exposure to transgenic corn cry1Ab gene in mussels seems to proceed by ingestion of microorganisms during feeding

GM herbicide tolerant crops

Generally associated with one of two herbicides:

Glyphosate (the act ive ingredient of Monsanto’s herbicide Roundup used with Roundup Ready GM crops, also sold by Monsanto).

Glufosinate, used with Bayer’s Liberty Link GM crops.

Toxic effects of herbicides on ecosystems

• Several new studies suggest that Roundup is far less benign than previously thought (www.greenpeace.org www.gmfreeze.org) .

• It is toxic to aquatic organisms such as frog larvae (Relyea, 2005) and there are concerns that i t could affect plants essential for farmland birds (ACRE. 2004).

• Wider impacts may exist. Glyphosate is associated with nutrient (nitrogen and manganese) deficiencies in GM Roundup Ready soya, thought to be induced by its effects on soil microorganisms (Zobiole et al. , 2011).

A Risk for tadpoles…

• Impact of four globally common pesticides (two insecticides, carbaryl [Sevin] and malathion; two herbicides, glyphosate [Roundup] and 2,4-D) on the biodiversity of aquatic communities containing algae and 25 species of animals were tested in labaratory.

• Species richness was reduced by 15% with Sevin, 30% with malathion, and 22% with Roundup, whereas 2,4-D had no effect. Both insecticides reduced zooplankton diversity by eliminating cladocerans but not copepods (the latter increased in abundance). The two herbicides had no effects on zooplankton, insect predators, or snails . Moreover, the herbicide 2,4-D had no effect on tadpoles.

• Roundup completely eliminated two species of tadpoles and nearly exterminated a third species, result ing in a 70% decline in the species r ichness of tadpoles.

• (Relyea, 2005)

A Risk for soil microbes..

• The objective of this research was to evaluate the microbiological interactions in the rhizospheres of GR2 and GR1 soybean and the performance of the cultivars with different rates of glyphosate applied at different growth stages.

• A greenhouse study was conducted using GR1 and GR2 soybean cultivars grown in a sil t loam soil . Glyphosate was applied at V2, V4 and V6 growth stages at three rates. Plants harvested at R1 growth stage had high root colonization by Fusarium spp.; reduced rhizosphere f luorescent pseudomonads, Mn-reducing bacteria, and indoleacetic acid–producing rhizobacteria; and reduced shoot and root biomass.

• Conclusions: Glyphosate applied to GR soybean, regardless of  cultivar, negatively impacts the complex interactions of microbial groups, biochemical act ivity and root growth that can have

subsequent detrimental effects on plant growth and productivity. (Zobiole et al . , 2011).

Increased weed tolerance to herbicide..

• Weed resistance to Roundup is now a serious problem where Roundup Ready crops are grown on a large scale (Johnson et al. , 2009). Increasing amounts of (Duke,2005) glyphosate or additional herbicides are needed to control these ‘SUPERWEEDS’, adding to the toxicity of food and the environment.

Increased weed tolerance to herbicide..

• Weed resistance to Roundup is now a serious problem where Roundup Ready crops are grown on a large scale (Johnson et al. , 2009). Increasing amounts of (Duke,2005) glyphosate or additional herbicides are needed to control these ‘SUPERWEEDS’, adding to the toxicity of food and the environment.

Increased weed tolerance to herbicide..

• Weed resistance to Roundup is now a serious problem where Roundup Ready crops are grown on a large scale (Johnson et al. , 2009). Increasing amounts of (Duke,2005) glyphosate or additional herbicides are needed to control these ‘SUPERWEEDS’, adding to the toxicity of food and the environment.

Morning glory..

• The researchers found that morning glory populations that have evolved resistance to the herbicide Roundup rely on self - fert il ization more than susceptible populations do.

• The increased reliance on self -ferti l ization may help perpetuate Roundup resistance by blocking the f low herbicide-susceptibil i ty genes from other plants, the researchers concluded.

• The results highlight the potential unforeseen consequences of human activit ies - in this case the widespread use of Roundup Ready crops, which are genetically modified to tolerate the herbicide - on wild plants such as weeds.

• 1 s t December, 2016

A news report

Health Risks…

• Three major health risks potentially associated with GM foods are: toxicity, allergenicity and genetic hazards.

• These arise from three potential sources, the inserted gene and their expressed protein, secondary or pleiotropic effects of the products of gene expression, and the possible disruption of natural genes in the manipulated organism. (Bawa and Anilakumar, 2013).

Health Risks…

Health Risks…

• “STARLINK” MAIZE provides an example of a food hazard caused directly by the expression of the inserted gene (Baulcombe, 2014).

• The modified plant was engineered with genetic information from Bacillus thuringinesis in order to endow the plant with resistance to certain insects. The inserted gene encodes a protein, called Cry9c, with pesticidal properties, but with an unintended, strong allergenicity.

• Several cases have been reported of allergic reaction in consumer safter consuming the “Starlink” maize.

Health Risks…

Does Roundup Cause Cancer?

• The product’s main ingredient,

glyphosate, is a “probable human carcinogen,” according to the International Agency for Research on Cancer (IARC). The agency is the cancer wing of the World Health Organization (WHO).

Written by Jamie Reno on August 25, 2016

Risk of toxicity

• Since the introduction of GM Bt (Cry1Ab) crops, both applicant companies and the European Food Safety Authority (EFSA) have assumed that the Cry1Ab toxin degrades rapidly in the human digestive system and is safe for human consumption.

• However, new studies show there is a lack of degradation in the human gut. This warrants further investigat ion as i t may imply this toxin has a greater potential to cause allergenic reactions than f irst thought. (Guimaraes et al . ,2010)

CONCLUSION

• The arguments, pro and con, reverberate the whole history of human technological development, pitt ing the clear advantages of intended consequence against the mucky possibil i t ies of unin-tended consequence.

• Indeed, a wise answer comprehends a diverse array of scientif ic expertise, not only in fi les of molecular biology, but also in agricultural economics, animal and micro- bial ecology, food technology, and immunology –a breadth of Expertise un likely to be found in one person.

07/08/17

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