Invasive Aphid Strikes Sorghum in the U.S.

Abstract

Invasions of alien insect pests often result in dramatic shifts in the entire ecosystems brought about by severe outbreaks of the pests exploiting new and frequently defenseless host plants. The explosive population dynamics of invasive insects often enable them to outcompete native pest species and alter both the abundance and diversity of communities of their natural enemies. These impacts are probably the most conspicuous and notorious when the invaded host plant is a key commodity crop and the invasive pest an aphid (Hemiptera: Aphididae). Aphids have a remarkable ability to overwhelm their plant hosts extremely rapidly owing to their parthenogenetic reproduction (i.e., daughters are clones of their mothers), live birth, and telescoping generations (i.e., the offspring of unborn aphids are already developing within their bodies). Aphids also attract exceptionally diverse communities of predators and parasitoids, which are strongly attracted to the volatiles emitted from plants attacked by aphids, albeit the natural enemies' attraction to invasive aphids often requires a period of adaption to recognize a new prey. Hence, when new species of aphids invade a new agroecosystem, their presence frequently creates an ?ecosystem earthquake' that can have profound implications for long-term stability of the system most directly affected by the invasive aphid as well as neighboring crops.