Importation biological control of other aphids

Aphids have been important targets of importation biological control. Part of the reason for this is that we have a lot of aphid species that are not native to our area. For example, aphid specialist Dr. Dave Voegtlin of the University of Illinois and Illinois Natural History Survey indicates that there are nearly 400 species of aphids in the state of Illinois, and a whopping 20% of these are introduced.

Accidental transport and introduction of aphids occurs easily for a few reasons. First, they are small and easily overlooked when plant material is moved around. Second, their tiny over-wintering eggs are also very easy to overlook; it is likely that some species have been introduced in this stage on dormant nursery stock, for example. Third, aphids reproduce by parthenogenesis through much of their life. This means that a single aphid, even an immature aphid, can start a colony that can eventually grow into a population and then an area-wide infestation. Fortunately, not all introduced aphids develop into serious pests, but there are many that have.

There are lots of natural enemies of aphids. These include several families of parasitic wasps, and several families of predators, including lady beetles, lacewings, flower flies, and others.

Because of their importance as pests and because of the diversity of natural enemies that attack aphids, several have been targets for importation biological control. Some examples are greenbug, Russian wheat aphid, pea aphid, woolly apple aphid, spotted alfalfa aphid, and walnut aphid.