The effect of transgenic nematode resistance on non-target organisms in the potato rhizosphere

A paper published today (26.11.02) in the December Issue of Journal of Applied Ecology by Cowgill et al describes the results of small-scale field trials that were used to assess the effect of PI-expressing potatoes on non-target soil organisms. The impact of a currently used PCN management option, the nematicide, aldicarb, on soil organisms was also studied.

The transgenic plants had an adverse effect on the fungal component of the soil microbial community, while the nematicide adversely affected the bacterial component of the microbial community. However, the changes brought about by the transgenic plants or nematicide use were small relative to natural fluctations in fungal and bacterial populations that were observed between sampling dates and growing seasons.

The observed changes in microbial community structure did not result in differences in soil function, as measured by C mineralization or rates of decomposition, between the treatments. There were also no differences in the abundance of soil microarthropds (mites and Collembola) or free-living nematodes between the treatments.

The study highlights the importance of including current management options when assessing the impact of transgenic plants and the importance of carrying out studies over several growing seasons.