Tracking the movements of transgenic endotoxins through complex food webs

  • Harwood, James (PI)
  • Obrycki, John (CoI)

Grants and Contracts Details


The planting of transgenic crops has increased rapidly since the commercialization of Bacillus thuringiensis (Bt) com in the mid-1990's. These crops convey significant benefits to natural enemy communities in agroecosystems through the reduced input of broad-spectrum insecticides. However, questions remain on the movement of Bt endotoxins through arthropod food webs and potential subtle effects on fitness parameters in some arthropod species. Through a series of focused hypotheses, we will quantify movement in the field, using antibody-based assays developed for Bt-endotoxins (CrylAb and Cry3Bbl), to detect the interaction pathways between transgenic com and complex arthropod food webs. We will quantify specifically the rates at which Bt-endotoxins flow through food chains, and potential major interaction pathways to carabids and spiders through the detrital food web. Tracking the flow of transgenic material along the food chain will indicate those natural enemies most likely to take up Bt-endotoxins, and allow laboratory experiments to quantify the effect of exposure at concentrations observed in the field. Our laboratory trials will test the hypothesis that endotoxin concentration in prey will influence fecundity parameters in predators through some (but not all) interaction pathways. This multi-faceted approach, utilizing antibody-based technology with field and laboratory studies, will provide a significant advance in our understanding of the movement of Bt-endotoxins in non-target food webs and aid in the risk assessment of transgenic organisms in the environment. Screening for Bt-endotoxin will follow protocols already designed for their detection in non-target arthropod species. To our knowledge, this will be the first study to both quantify the potential for Bt-endotoxins to flow through invertebrate food webs in the field and examine potential chronic effects of field-determined levels of Bt-endotoxins on arthropod predators.
Effective start/end date9/15/069/14/10


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