DETECTION OF DNA-ADDUCTS IN DECLINING HOP PLANTS GROWN ON FIELDS FORMERLY TREATED WITH HEPTACHLOR, A PERSISTENT INSECTICIDE

Hop decline was observed in Alsace, eastern France, in reparcelled sug ar beet fields formerly abundantly treated with an insecticide, heptac hlor. Leaves were collected from 'declining hops' grown in an heptachl or-contaminated area and from 'healthy hops' grown in a soil not conta minated by heptachlor. These two samples came from hop vines treated w ith other usual pesticides. 'Control' hop leaves came from soil neithe r treated with pesticide nor contaminated with heptachlor. Hypermodifi ed nucleotides (DNA adducts) were detected using the P-32-postlabellin g method. No detectable DNA adducts were found in the 'control' specim en, whereas eight adducts were detected in the 'healthy hops' specimen , probably due to the usual pesticide treatment. However, 16 adducts, nine of which were new adducts, could be detected in the 'declining ho ps' specimen. It may therefore be supposed that the presence of these hypermodified nucleotides perturbs gene expression and so contributes to the hop decline. In addition, to confirm the genotoxicity of heptac hlor, it is shown that it induces DNA adducts in bean-cell suspension culture as well. Finally, it is proposed, in the case of alternate cul tures scheduled in fields which were formerly treated with pesticides, adapted to other cultures, that particular attention should be given to the history of the soils.