Controlling the raspberry beetle Byturus tomentosuswith semiochemical mass-traps in Switzerland

Abstract: The raspberry beetle Byturus tomentosus (De Geer) is a major pest of raspberries inmountainous regions of Switzerland. Today there is a demand for alternative methods to controlpests in order to minimize pesticide residues on fresh fruits. Raspberry beetles were mass-trappedwith a semiochemical trap (floral attractant) that was developed by the Scottish Crop ResearchInstitute. Mass-traps were installed in a commercial raspberry field in the Valais (1300m alt.) at adensity of 50 traps per hectare. In 2008, traps were installed shortly before flowering (beginningof June) and B. tomentosus adults were captured from the start. In 2009 and 2010, traps weretherefore installed two and four weeks earlier, respectively. Nonetheless, B. tomentosus adultswere captured from the beginning and the total number of individual captured was considerablyhigher than in 2008. Thus, raspberry beetles begin to fly much earlier than previously expected.From 2008 to 2010, the proportion of damaged fruits decreased from 9.6% to 3.4%. However,these damages were higher than in the insecticide treated control plot, since there were only 0%and 1.3% fruits damaged in 2009 and 2010, respectively. The conventional intervention withthiacloprid is therefore still more efficient and cheaper than mass-trapping. Nonetheless, our trialsshow that traps are highly attractive and that they might be a useful asset for integrated pestmanagement and organic farming.