One of New Zealand's most successful tourist ventures: fishing, would be under threat if GM tree and crops containing Bt are ever allowed to be grown especially near water ways.
New research has found that residue from Bt corn leaves, cobs and pollen endanger aquatic insects (1). Earlier studies found that GM DNA in pollen survived in river sediments and recombined to produce the Bt toxins in bacteria. The cry1Ab gene persisted for more than 21 days in surface water and was still detected after 40 days in clay- and sand-rich sediments. Sediments taken from the St Lawrence river, 82km down stream, had levels of Bt-toxin 5 times higher than in drainage waters and sediments near agricultural land.(2)
"With New Zealand�s temperamental weather and winds it makes it inevitable that we could not contain GM plant material and it would have detrimental results for our river systems," she says.
The surface water from Bt corn field runoff and floods washing into streams has been shown to affect important aquatic insects, like butterflies, moths, beetles and flies, severely stunting growth and affecting reproduction. The most affected insect was the caddis fly (Lepidostoma.liba) a succulent treat for fish such as trout and salmon.
�The new evidence highlights that material from transgenic Bt corn is persistent and toxic and could adversely affect aquatic insects especially caddis flies� says Claire Bleakley of GE Free NZ(in Food and Environment).
The first detailed research on the by products of GM plants on the aquatic stream organisms published in PNAS has reported that aquatic insects are highly susceptible to Bt pollen from GM corn. Detritus that entered streams was carried up to 2kms from the field. Studies on streams insects fed on Bt endotoxin from corn had lower growth rates, loss of vitality/activity and reduced fertility and reproductivity. These results would severely impact on the fish, amphibians and birds in the riparian strips who prey on the insects.
New Zealand�s rivers are already affected by nutrient run off and in places extensive habitat degradation. This new evidence indicates GM plants could damage river ecosystems and affect the trout and salmon fisheries.
"It is the time of year for farmers to plant corn. It is incumbent on MAF to have stringently enforced their "zero" tolerance for GM corn seeds so there is no chance that such events could occur" said Mrs Bleakley
ERMA has previously approved field trials of Bt crops in New Zealand, and the decision is under scrutiny following a challenge to the High Court on points of law.
Claire Bleakley (06) 3089842 Mob: 027 348 6731
(1)Rosi-Marshall E., Tank J., Royer T., Whiles M., Evans-White M., Chambers C., Griffiths N., Pokelsek J., and Stephen M., (2007) Toxins in transgenic crop byproducts may affect headwater stream ecosystems, PNAS Vol: 104; 41; p.16204- 8211;16208 www.pnas.org_cgi_doi_10.1073_pnas.0707177104
(2) Douville M, Gagn� F, Blaise C, Andr� C.(2007) Occurrence and persistence of Bacillus thuringiensis (Bt) and transgenic Bt corn cry1Ab gene from an aquatic environment. Environment Canada , St. Lawrence Centre, Epub 66(2):195-203. PMID: 16499967 [PubMed - indexed for MEDLINE]
(2) Gagn� F., Douville M., Blaise C., Marineau A.(2001) Release and Potential Impacts of Biological Toxins Bt Genetically-Modified Corn Crops and Biopesticide Application. St. Lawrence Centre, Environment Canada,