Alien Species and the Extinction Crisis of Hawaii's Invertebrates

In 1962, Rachel Carson eloquently and convincingly argued that the intensive and widespread use of pesticides was resulting in the pollution of ecosystems, declines in wildlife, and human health problems. These poisons were primarily insecticides used against what she called "an avalanche" of resistant insects. Most people share this concept of insects and other invertebrates as a natural disaster (Kellert 1993), and concerns for invertebrate conservation seem almost oxymoronic. Even the Endangered Species Act withholds protection for any insect viewed as a significant pest. There has never been a documented invertebrate extinction from pesticides (Howarth 1991), but, as is often the case, where our technology fails our bumbling and perseverance succeed. Like mud tracked across a living room floor, as humans perambulate, roll, sail, and fly across the face of the earth, we scatter other organisms into areas they don't belong. For example, over 2500 alien arthropods are now established in Hawaii (Howarth 1990, Howarth et al. 1995, Nishida 1992), with a continuing establishment rate of an appalling 10-20 new species per year (Beardsley 1962, 1979). Unlike chemicals, established alien organisms are permanent, they propagate, and they disperse. The visual result is a homogenization of the biological landscape. The often unseen result is the disappearance of native species, including invertebrates, due to predation, competition and associated diseases of the alien organisms. In this article, I describe how the introduction of alien species into the Hawaiian Islands has resulted in an almost unimaginable decline and extinction of invertebrates, and repercussions on the ecosystems.