Weed control through the enhancement of beneficial ground-dwelling invertebrates

Background/Question/Methods

There has been a strong emphasis nationwide to move away from conventional tillage systems due to the negative impact tillage can have on soil quality and erosion potential.  Less tillage often requires greater reliance on herbicides, which can have a negative impact on the quality of surface and ground waters, and can lead to the development of herbicide resistant weed communities.  In contrast to these negative environmental consequences of reduced tillage, there are aspects of reduced tillage systems that are compatible with sustainable pest management.  Here our goal was to create and evaluate a reduced tillage system in an attempt to enhance the granivorous invertebrate community while effectively controlling weeds with a focus on soil and water conservation.   The effects of integrated (a reduced tillage system), no tillage, and organic transition cropping systems on seed eating invertebrate activity-density and invertebrate weed seed predation were evaluated in a maize/soybean system.  The systems (integrated, no-till and organic) were arranged in the agricultural field in a randomized complete block design with 4 replicates and were sampled for 2 years.

Results/Conclusions

The integrated weed management system employed in this study increased the activity-density of four of the five examined granivorous invertebrate taxa when compared to either no-till or organic systems. This integrated system was not detrimental to any granivorous invertebrate population or to weed seed predation.  Correlations between seed removal and taxon activity-density largely supported expected trends with activity-densities of the taxa known to be important seed predators (Gryllidae, H. pensylvanicus and P. melanarius) being significantly correlated (p < 0.05) or marginally correlated (p < 0.075) with seed removal rates.  Likewise, it was expected that activity-densities of Aranea, Opiliones, and insectivorous carabids would exhibit significant negative correlations (p < 0.05) with seed removal rates, as was found.  Our results suggest that integrated weed management strategies can reduce herbicide application while effectively controlling weeds.