We all have an intuitive understanding that organisms interact with one another, through such events as predation, parasitism, and even mutualism. It is easy for us to relate to plants and animals this way because we too are often focused on direct interactions between ourselves and the people and things around us. Less often do we consider how we are indirectly linked to one another; that is, how two things influence each other through a shared intermediary.
Field ecologists are often interested in multiple species that are connected to one another through a third living thing, including some in the Gratton Lab at theUniversityofWisconsin-Madison. Steve Hong and his colleagues have been studying how two pests of the important crop soybean affect the plant and one another. Soybean has historically fallen victim to tiny worms called nematodes that attack the plant below the surface. Above ground the plant is fed upon by tiny insects known as aphids which have been introduced to Wisconsin only in the last decade.
Experiments in the laboratory and the field with soybean and its above and below-ground pests have revealed the complicated relationships among them. Winged aphids have been shown to prefer soybeans that are uninfected by the nematodes, both in the lab and in the field. However aphid growth and reproduction were not reduced on plants infected by nematodes versus those that were not infected. However yield and seed production were reduced in the field by nematodes and aphids respectively.
Hong, SC, A MacGuidwin, C Gratton. In review. Soybean aphid (Aphis glycines Matsumura) and soybean cyst nematode (Heterodera glycines Ichinohe) interactions in the field and effects on soybean yield.