The impact of biofumigation on non-targeted soil arthropods and subsequent host-mediated interactions with aboveground insects

Cultural control, a component of integrated pest management, can provide crops with a competitive edge against pests and reduce the need for frequent insecticide applications. However, because cultural practices are assumed to be safer than synthetic pesticides, there has been relatively less focus on their potential negative impacts on non-targeted organisms and needs to be studied further. For example, although biofumigation, i.e., the soil incorporation of brassica cover crops or their byproducts, can suppress subterranean pests, they can also negatively impact non-target organisms, some of which are important contributors to soil health and beneficial to our agroecosystem. The present greenhouse study is developed to determine the effect of soil-incorporated brown mustard seed meal on the springtail Folsomia candida (Collembola: Isotomidae), as a non-target organism. Initially, the soil incorporation of brown mustard seed meal significantly reduced springtail populations, however, springtail populations rebounded within 3 weeks of soil incorporation and proceeded to exceed those in non-treated controls. We further examined the potential plant-mediated impacts of soil biofumigation on the bird cherry-oat aphid Rhopalosiphum padi L. (Hem., Aphididae). In our preference bioassays, aphids initially avoided the plants grown in biofumigated soil and visited control plants more frequently; this preference disappeared after 24 hours. Aphid reproduction results showed a significant interaction between treatments and repeat (time-block), and additional data is needed before concluding. The result of this project will help to inform the development of management practices that can simultaneously control soil-borne pests and minimize harmful impacts on soil health and ecosystem function.