Document Detail

Responses of stream macroinvertebrates to Bt maize leaf detritus.
MedLine Citation:
PMID:  21049882     Owner:  NLM     Status:  MEDLINE    
In the midwestern United States, maize detritus enters streams draining agricultural land. Genetically modified Bt maize is commonly planted along streams and can possibly affect benthic macroinvertebrates, specifically members of the order Trichoptera, which are closely related to target species of some Bt toxins and are important detritivores in streams. The significance of inputs of Bt maize to aquatic systems has only recently been recognized, and assessments of potential nontarget impacts on aquatic organisms are lacking. We conducted laboratory feeding trials and found that the leaf-shredding trichopteran, Lepidostoma liba, grew significantly slower when fed Bt maize compared to non-Bt maize, while other invertebrate taxa that we examined showed no negative effects. We also used field studies to assess the influence of Bt maize detritus on benthic macroinvertebrate abundance, diversity, biomass, and functional structure in situ in 12 streams adjacent to Bt maize or non-Bt maize fields. We found no significant differences in total abundance or biomass between Bt and non-Bt streams, and trichopterans comprised only a small percentage of invertebrate biomass at all sites (0-15%). Shannon diversity did not differ among Bt and non-Bt streams and was always low (H' range = 0.9-1.9). Highly tolerant taxa, such as oligochaetes and chironomids, were dominant in both Bt and non-Bt streams, and macroinvertebrate community composition was relatively constant across seasons. We used litterbags to examine macroinvertebrate colonization of Bt and non-Bt maize detritus and found no significant differences among litter or stream types. Our in situ findings did not support our laboratory results; this is likely because the streams we studied in this region are highly degraded and subject to multiple, persistent anthropogenic stressors (e.g., channelization, altered flow, nutrient and pesticide inputs). Invertebrate communities in these streams are a product of these degraded conditions, and thus the impact of a single stressor, such as Bt toxins, may not be readily discernable. Our results add to growing evidence that Bt toxins can have sublethal effects on nontarget aquatic taxa, but this evidence should be considered in the context of other anthropogenic impacts and alternative methods of pest control influencing streams draining agricultural regions.
Catherine P Chambers; Matt R Whiles; Emma J Rosi-Marshall; Jennifer L Tank; Todd V Royer; Natalie A Griffiths; Michelle A Evans-White; Amber R Stojak
Publication Detail:
Type:  Journal Article; Research Support, U.S. Gov't, Non-P.H.S.    
Journal Detail:
Title:  Ecological applications : a publication of the Ecological Society of America     Volume:  20     ISSN:  1051-0761     ISO Abbreviation:  Ecol Appl     Publication Date:  2010 Oct 
Date Detail:
Created Date:  2010-11-05     Completed Date:  2010-12-02     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  9889808     Medline TA:  Ecol Appl     Country:  United States    
Other Details:
Languages:  eng     Pagination:  1949-60     Citation Subset:  IM    
Department of Zoology and Center for Ecology, Southern Illinois University, Carbondale, Illinois 62901, USA.
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MeSH Terms
Bacillus thuringiensis / genetics*
Bacterial Proteins / chemistry,  genetics*,  toxicity
Biodegradation, Environmental
Endotoxins / chemistry,  genetics*,  toxicity
Environmental Monitoring
Hemolysin Proteins / chemistry,  genetics*,  toxicity
Invertebrates / drug effects*
Plant Leaves
Plants, Genetically Modified
Rivers / chemistry*
Water Pollutants, Chemical / toxicity*
Zea mays / genetics*
Reg. No./Substance:
0/Bacterial Proteins; 0/Endotoxins; 0/Hemolysin Proteins; 0/Water Pollutants, Chemical; 0/insecticidal crystal protein, Bacillus Thuringiensis

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