To control grubs consuming the roots of sugar cane, scientists applied silica, like finely ground sand, to the soil. The bioavailable form of silicon (soluble sodium silica) was taken up by plants, but not directly. Arbuscular mycorrhizal (AM) fungi were needed to bring the silica into the plant roots. The result was gritty plant tissue. The silica has no effect on humans or livestock that consume the plant tissue. For insects, however, the silica can damage mouthparts and make the plant less palatable. This works on both below-ground pests, such as grubs, and insects that eat the leaves. Unlike the pesticides that accumulate in the food chain, the silica has no effect on birds or mammals that consume the gritty grubs.
Host plant colonisation by arbuscular mycorrhizal fungi stimulates immune function whereas high root silicon concentrations diminish growth in a soil-dwelling herbivore. Adam Frew, Jeff R. Powell, Ivan Hiltpold, Peter G. Allsopp, Nader Sallam, and Scott N. Johnson. Soil Biology and Biochemistry, 2017, Volume 112, Pages 117-126.
- Janet Wallace