Consequences of the neonicotinoid seed treatment ban on oilseed rape production – what can be learnt from the Swedish experience?

Abstract

There has been great concern about negative effects on crop production resulting from the ban on insecticide seed treatments containing neonicotinoids. I examine how the neonicotinoid ban has affected crop protection and crop production in oilseed rape (Brassica napus L.) using Sweden as a case study and compare the Swedish situation with that in leading countries growing winter and spring oilseed rape, respectively. The cropping area of winter and spring oilseed rape in Sweden has increased by approximately 40% to around 100 000 ha and decreased by approximately 90% to around 4000 ha, respectively following the ban and there are trends for increased pest and disease pressure. Overall, however, the ban has not had any major impacts on total oilseed rape cropping area or crop yields per hectare of either winter or spring oilseed rape, which is in contrast to elsewhere in Europe. In Germany and the United Kingdom, for example, the cropping area has decreased following the ban on neonicotinoid seed treatments, attributed to increased insect pest pressure especially from cabbage stem flea beetle, Psylliodes chrysocephala. I conclude that winter oilseed rape has remained a viable crop to grow in Sweden without insecticide seed treatments, but that further investments into integrated pest management are needed for sustainable insect pest control in oilseed rape in the future. © 2021 The Author. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Cold winters drive consistent and spatially synchronous 8‐year population cycles of cabbage stem flea beetle

“…Since the resource base is an annual agricultural crop delineated by human managed decisions, we can rule out the hypothesis that bottom‐up forces, in the form of long‐term variation and delayed feedbacks in plant quality, are driving the population cycles for P. chrysocephala in annual winter oilseed rape fields. Though large‐scale changes in agriculture can dampen pest population cycles (Bell et al, 2012), we see no such shifts in the amplitude and periodicity of P. chrysocephala cycles that could be attributed to changes in the area planted to winter oilseed rape in Scania (Figure S8), overall pesticide use (Figure S9) or policy‐driven changes, such as the ban of neonicotinoid seed treatments since 2013 (Lundin, 2021).…”

How contradictory EU policies led to the development of a pest: The story of oilseed rape and the cabbage stem flea beetle

“…It has been shown that diversified landscapes with higher proportions of semi-natural areas exhibit lower pest abundance and/or higher biocontrol services in fields than simple large-scale landscapes with low proportions of non-crop areas (Bianchi et al, 2006;Gagic et al, 2021;Landis et al, 2008;Veres et al, 2013). Although there have been some studies that showed CSFB population increases over the period that the area of the crop has expanded (Collins, 2017;Lundin, 2021;Nilsson, 2002), none have yet clearly related these with increases in OSR grown area. However, it has been shown how pollen beetle (Brassicogethes aeneus) became a troublesome pest after 3-4 years of intensive OSR cultivation and remains so (Hokkanen, 2000); indeed, reproductive success of pollen beetles has increased by 200%-300% during the first 16 years of OSR cultivation compared to those beetles living on cruciferous weeds (their natural host plants; Hokkanen, 2000).…”

Success, despite another plague year

“…Safety assessments of the effects of genetically‐modified crops on bee pollinators in the EU are reviewed 38 . Lundin discusses the Swedish experience in banning oilseed rape seed treatments with neonicotinoid insecticides 39 …”