Nancy Gore Hunger Professor University of Tennessee Knoxville, Tennessee
Elusive extinctions? Insect losses driven by invasions (especially insect invasions) Daniel Simberloff, University of Tennessee The role of biological invasions in the sixth mass extinction is controversial, though in some circumstances (e.g, vertebrate invasions of oceanic islands) many incontrovertible examples are known. On mainland, the decline to extinction is often a slower process, and though invasions are frequently implicated as one of several causative factors, solid evidence is often lacking. Surely, just as the number of imperiled insects is drastically underestimated (e.g., the U.S. endangered species list includes 896 angiosperms, 382 vertebrates, and only 93 insects), the number eliminated or threated by invasions is barely known. This statement is even truer for threat or extinction by introduced insects than for threat or extinction by other introductions, such as those of plants that replace an insect’s host plant or change a fire regime. In a few cases, such as insects introduced for biological control, there is some evidence of an important role in decline of native insects. In other instances, the role is less certain, but for the classes of invasive impacts recognized for other species (predation, parasitism, disease, competition, habitat change, and various indirect effects) insect examples are known and are probably greatly outnumbered by unrecognized cases.
