Impact of large strip cropping system (24 and 48 rows) on soybean aphid during four years in organic soybean

• Large strip cropping of four crops reduced soybean aphid abundance.
• A better natural control of soybean aphid was observed in strips.
• Land equivalent ratio was higher in 18 m strips than in control plots, indicating potential higher economic return.

Strip cropping could be used to deliver several eco-services, including reducing pest pressure. The objective of this study was to evaluate the impact of the management of a strip cropping system of soybean, wheat, corn and vetch on soybean aphid Aphis glycines Matsumura, its natural enemies and on the harvest of soybean. Experimental set up of 18 m and 36 m strips were installed in 2006 on an organic farm at Les Cèdres, Québec, Canada and compared with control plots of 180 m of soybean. Each plot was replicated two times on the farm and measured 1 km long. Observations of soybean aphid and natural enemies were carried out on 18 plants per replicate strips and control plots during summer 2007–2010. Abundance of soybean aphid was reduced between 33 and 55% in strips compared with the control plots during both high infestation years (2007 and 2009), while natural control (prey/predator ratio and parasitism rate) was more efficient in strips in 2009 and 2010. Land equivalent ratio (LER), an indicator of yield production was higher in 18 m strips than in control plots. Strip cropping could be envisaged as an effective managing tool against soybean aphid in North America.