Open access publications in the SLU publication database

Abstract

Plants genetically modified (GM) for insect resistance (IR) have to be tested and compared to their non-GM counterparts with respect to several aspects. This thesis summarizes the effects of three transgenic lines of oilseed rape (Brassica napus) expressing pea (Pisum sativum) seed lectin (PSL) in the pollen on a target pest: the pollen beetle (Meligethes aeneus), and a non-target insect: the honey bee (Apis mellifera). The competitive ability of the transgenic plants was tested to evaluate potential invasive characters. Finally, attitudes towards GM crops among Swedish farmers were surveyed. Pollen beetle adults and larvae were exposed to three PSL expressing plant lines and two control lines without any PSL. Fourteen life history parameters were studied and significant differences between transgenes and controls were found for egg size and larval mortality. This means that the modification does not prevent direct damage to the attacked crop but the effects could, together with the action of natural enemies, lead to a reduced pollen beetle population. The sensitivity of honey bee larvae to PSL containing pollen was tested by feeding them diets with high levels of transgenic or control pollen. The addition of pollen had a positive effect on developmental time and larval weight but no differences were detected between transgenic and non-transgenic pollen. Competitive ability was tested by growing transgenic plants either in monoculture or mixed with control plants, with or without pollen beetles, and with or without pollinators (bumblebees). Plant characters related to plant fitness were measured but transgenic plants did not benefit from the transformation regarding pest damage. However, yield was higher on transgenic plants when grown mixed with control plants than when grown in monoculture, and the opposite was true for control plants. A majority of the surveyed farmers were negative to GM crops and considered consumers' unwillingness to buy GM products as the largest drawback, while higher yield was considered the largest potential benefit from growing such crops.