Non-native Arthropods

Globalization, a process that we are increasingly aware of, has been going on for a very long time. Nature supports restricted globalization but this process is usually slow. Plant seeds spread on the wind and water and hitch rides in and on animals. Animals fly, walk, swim and hitch-hike.

Increasingly, globalization of the world's flora and fauna has been assisted by people. In the early days, mass migrations, explorers, traders and colonists all moved plants and animals around, but this was rather limited. The fauna on many islands suffered greatly from the introduction of domestic animals and rats. Early colonists brought the European Honey Bee to North America. Legends from various Pacific islands talk of how visitors spread mosquitoes to various islands. Some plants, now regarded as weeds, and some insects were introduced in seed stock and other plant material. Today, as people and products are moved about, so, frequently, are various arthropods - mainly insects, spiders and mites - despite all of our precautions.

Most introductions are not intentional. The Cabbage Butterfly, the commonest white butterfly seen along our coast, arrived from Europe in the middle of the last century. The Argentine Ant, also common here, is native to South America. The Spruce Sawfly, Japanese Beetle and Gypsy Moth are some other successful invaders. Once sufficient numbers arrive (and this can be just one pregnant female), the species usually does quite well due to the lack of predators, and often displaces native species. Some colonizers exhibit behavior not seen in their native lands. Non-native arthropods can easily go unnoticed until they are well established.

Numerous predators, particularly ladybird beetles, parasitic wasps and parasitic flies, have been purposely introduced in different countries to help control non-native insects. Locally, a parasitic wasp from Mexico has been enlisted in the fight against the Giant Whitefly. In some cases, herbivorous insects have been introduced to control non-native plants. While precautions are taken to avoid creating new problems, these have not always been sufficient.

As we move towards a global culture, we also move towards a distinctly human-defined global environment, one whose foundation lies in continual disturbance and energy intensive practices. Along many coasts, we are developing extensive, extended megacities. A relatively new field, urban entomology, and a large part of our pest control industry specialize in arthropods adapted to this strictly human environment. In order to feed and house our growing numbers, we have constructed a global agricultural environment concentrating on a few plants which cover substantial contiguous acreages. These areas are ideal for pest insects that, once established, are difficult to eradicate. In the past, the wholesale application of pesticides has only honed the strategies that insects use to bypass plant defenses, so integrated pest management techniques aimed at limiting rather than eliminating damage are in more general use now. (Paradoxically, controlling insects and / or fixing the damage caused by them is good for the economy because it increases the gross national product.)

Increasingly the globalization of our world is associated with extinctions. Out of this is rising a flora and fauna more globally distributed, one based on adaptability and determined largely by the environment we decide to live in.

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Ron Lyons (volunteer 1990-1999)
Chula Vista Nature Center, 1000 Gunpowder Point Drive, Chula Vista, CA 91910-1201