Neonicotinoids in sugar beet cultivation in Central and Northern Europe: Efficacy and environmental impact of neonicotinoid seed treatments and alternative measures

The use of neonicotinoids in sugar beet seed treatments is widespread across Europe because they effectively control most harmful arthropods. In most European countries, neonicotinoids (clothianidin, thiamethoxam and imidacloprid) are used in seed treatments on almost 100% of conventionally cultivated sugar beet fields. Additional foliar insecticide applications during the growing period with e.g. carbamates or pyrethroids are not conducted on most fields. Currently, the use of neonicotinoids in seed treatments of bee attracting crops such as rapeseed is banned in the European Union. The European Food Safety Authority will re-evaluate the risk for pollinators posed by neonicotinoids in seed treatments presumably by 2017. A possible total ban of neonicotinoids also in beet crops is likely which might increase the application of foliar insecticides throughout the growing period. In this article, the significance of neonicotinoids for the Central and Northern European sugar beet cultivation is reviewed and alternatives are considered. Current and former uses of insecticides, frequency of arthropod pests and their control, effects on yield and problems arising from resistances against insecticides are included in this review as well as environmental hazards. Exposure of non-target organisms to neonicotinoids in sugar beet seed treatments seems to be rather unlikely: both seed pelleting procedure and drilling technique conform to highest technical standards in terms of abrasion and drift of insecticides. The release of neonicotinoids to the environment via guttation or residues at harvest is low. Moreover, neonicotinoids in seed treatments can hardly be replaced as a control measure for the most damaging pest Myzus persicae Sulz. due to a lack of effective alternatives together with resistance of many populations against carbamates and pyrethroids. To control damaging seedling pests, tefluthrin in seed treatments often might be as effective as neonicotinoids, but its efficacy can be reduced under severe pest pressure of e.g. Atomaria linearis Steph. However, damaging arthropod pests do not occur in every field in every year. Thus, there is a potential for reducing the area treated with neonicotinoids in sugar beet. Monitoring systems and models to identify regions (and years) with a high risk of harmful pest incidences should be developed and decisions on the use of insecticides in seed treatments should be based on the probability of pest occurrence. Such situation-based pest management practices are needed to improve the sustainability of agricultural systems and to reduce the potential for harmful side effects of insecticides for the environment.