Biotechnology, environmental forcing, and unintended trophic cascades

Abstract

A long ongoing discussion between scientists and policy decision-makers seems to have entered recently into a new phase. The consequences of release of transgenic crops into the environment are being discussed not only by scientists but also by farmers, environmental groups and politicians, while an increasing amount of data is becoming available at all biological scales, including the field level. However, data still rely on experiments designed to capture direct consumer-resource interactions.Here we argue that we should attempt to concentrate on the ecosystem functioning of soil biota under geneticallymodified (GM) plants, because functional and mechanistic analysis of the multitrophic effects of GM plants on soil biota is still lacking. It is our opinion that we should avoid addressing taxa and soil communities separately, but link them at their functional level. We shall explain why, using examples from ecosystem services, allometric scaling, and soil food webs. The energy flow of any food web under stress incorporates several factors and pooled information on ecosystem services and on the different responses of soil invertebrates to induced perturbations in other trophic levels. Therefore, we will systematically focus on the complementarities of these approaches.

Food preference in the woodlouse Porcellio scaber (Isopoda) in a choice test with fungicidal GM wheat

“…Beside such benefits, there might also occur ecological and environmental risks. As GM plants will eventually be grown under field conditions, they may change ecological interactions (from what they were and how they developed and changed over time before) and ecosystem services like decomposition (Mulder and Lotz 2009). Prior to release of GM plants, potential risks have to be defined and characterized in an ecological risk assessment (ERA).…”

Effects of intraspecific variation in white cabbage (Brassica oleracea var. capitata) on soil organisms

“…Depending on the trophic level in the soil food web, the level of interaction with the plant differs. Root feeders directly interact with living plant roots, whereas detritivores and predacious soil organisms feed on plant litter or on second and higher trophic level organisms (Berg and Bengtsson 2007;de Ruiter et al 1995;Holtkamp et al 2008;Mulder and Lotz 2009;Mulder et al 2003), leading to a more indirect interaction with living plant roots (Wardle et al 2004). Due to their direct exposure to the roots, rootassociated and lower trophic level organisms in the soil food web are more likely to be affected by variation in plant quality than other soil organisms (Wardle 2006).…”

“…Due to their direct exposure to the roots, rootassociated and lower trophic level organisms in the soil food web are more likely to be affected by variation in plant quality than other soil organisms (Wardle 2006). Nevertheless, decomposer organisms and higher trophic level organisms can potentially be influenced via changes in the quality and quantity of litter, in root-exudates, or via differences in the quality or quantity of prey or host species (Mulder and Lotz 2009). In the present study, we examine how intra-specific variation among plant cultivars may affect these different components of the soil food web.…”

“…Therefore we analyzed the fate of organisms that feed on living plant roots and organisms belonging to the detritus-based food web. These soil organisms differ in their nutrient requirements, body size, and growth/reproductive rates (Mulder and Lotz 2009). We tested the hypothesis that the intraspecific chemical variation in our plants will affect root-feeding nematodes due to their close contact with the roots and we determined the extent to which this variation influences other important groups such as mites, Collembola, earthworms, and enchytraeids in the soil food web.…”

Genetically Engineered Antifungal Wheat has no Detrimental Effects on the Key Soil Species Lumbricus terrestris

“…Genetic engineering is, beside potential benefits like more agricultural output or less pesticide use, accompanied by concerns about potential detrimental effects on the environment. GE plants will possibly change ecological interactions and ecosystem services such as decomposition since they will eventually be grown under field conditions (Mulder and Lotz, 2009). Hence it is essential to do ecological risk assessments (ERA) prior to the release of GE plants and assess all effects on their surrounding environment and evaluate whether ecosystem services and functioning are affected.…”