Designing experimental protocols to investigate the impact of GM crops on non-target arthropods
Year: 2008
Type: report
Abstract: EU legislation requires risk-assessment studies to be carried out before approval can be granted to applications for field tests and commercial cultivation of genetically modified (GM) crops. Although risk-assessment studies are necessary it has not been specified which laboratory experiments should be carried out. This report describes detailed protocols for such experiments after giving the rationale for the type of experiments proposed. A previous study identified 19 non-target arthropod species for use in laboratory tests. This report continues the research and presents experimental guidelines for investigating the impact of GM crops on non-target arthropods.Most research investigating the impact of GM crops on non-target arthropods has focussed on using protocols based on studies connected with synthetic pesticides, where the main parameter measured is that of mortality. However, mortality measurements fail to take sub-lethal effects into account, and changes in development time or fecundity can have important consequences for non-target arthropod populations. For instance, if organisms are sterilized but not killed, a mortality test will result in no effect whereas the population size would be strongly affected. The goal of assessing effects on non-target arthropods is to see whetherpopulations of non-target organisms are negatively affected and if so, to what extent. This encompasses more than only lethal effects and sub-lethal effects can play an important role. This report highlights the need to standardise and improve experimental techniques. Population growth measurements are suggested as an alternative to simple mortality tests because they combine both lethal and sub-lethal effects into one meaningful measure. An easy to carry out assessment of population growth is to address the instantaneous rate of increase (ri): a census of the population is taken at time t0, followed by a census at a time after which substantial reproduction has occurred (such as time of maximum growth). Incorporating these measures into a simple equation generates an actual measure of the population growth rate. This technique can be used in either laboratory or field studies andenables researchers to obtain important data for a minimum of effort and expense.The report presents detailed experimental protocols which can be used to investigate the impact of GM crops on non-target arthropods, including predators, parasitoids, pollinators and soil-dwelling organisms by making use of population growth measurements, such as the instantaneous rate of increase, to determine the impact on population fitness.
Authors: D.S. Charleston, Marcel Dicke
Language: English
Subfield: Plant Science
Domain: Life Sciences
SDG: Zero hunger
Open Access status: green
OpenAlex ID: W2123186012