Non Native Pests
Also known as Invasives, Prohibited Exotic Species and Noxious Weeds, Non Native Pests are plant and animal species that have been introduced to areas outside their natural habitat. While these species may be harmless and even at times beneficial in their own environment, they have the potential of completely destroying the delicate balance of their new habitat.
Why should I be aware of this?
History shows that humans are largely to blame for introducing Non Native Pests to new habitats. During the 17th and the 18th centuries, when colonizers set up colonies far away from their home countries, they often brought non-native species to the colonies. Their reasons were many, ranging from wanting a favoured animal or plant available locally, to using animals from their home country to control a native pest. One example is tha of cane toads, natives of South America which were introduced in the US to control sugar-cane pests.
In addition, human habitation and land clearing put significant pressure on local species, and disturbed habitat is often prone to invasions by Non Native Pests. Sometimes the alien species can even be a pre-existing one that attains dominance when other species begin to decline or some factor in their environment undergoes a change.
Non native pests and environment
Non native pests are capable of wrecking entire environments, causing extinction of local species and result in untold losses in agriculture and forestry.
The invasion of Non Native Pests can reduce biodiversity, degrade habitats, alter native genetic diversity and further risk endangered plants and animals! In areas with highly endemic flora and fauna such as Madagascar and Hawaii, alien species have spelled doom for many native species.
Non Native species often host or cause diseases that have a great impact on human health. These exotic diseases can take human as their host. Moreover, introduced birds, rodents and insects can serve as vectors of human diseases. An example of an introduced disease is the spread of the West Nile virus by mosquito vectors across North America resulting in the deaths of humans, birds, mammals, and reptiles.
All about non native species
Modern-day examples of non-native species include many exotic parrot species that escaped from bird owners, African cichlid fish in the south Florida canals that were released from aquaria, squirrel monkeys that were released or escaped from tourist attractions all over the West, and red-eared sliders, the popular “baby turtles” sold in the pet trade and are now found throughout the US.
The impact of non native pests
Every ecosystem has its own natural balance and controls, and the native plants and animals are adapted to these conditions. When an alien life form is introduced to it, a lot of things can happen. The Ten Percent Rule is a general rule of thumb that says of all non-native species that are released into new ecosystems, about 10% survive, and of these survivors, about 10% (or 1% of the original number of species released) become invasive.
Of the ten per cent that survive, a species may adapt so well, it becomes indistinguishable from native species. With it come its pathogens, which may have adverse effects on the native population. In a few extreme cases, this has led to the extinction of the related native species.
Some non natives actually find more food sources or higher nutrient levels in their new environment, which could cause their population to escalate beyond control. This has been the case with the introduction in parts of the US, of Johnsongrass and Bahaigrass, both thought to be a good pasture grasses at the time, which then grew out of control in their new environment.
Yet other non natives could compete for the same natural resources with local species. If those species are unable to adapt to the more competitive environment, they could gradually die out.
Lastly, Non Native Pests could mix with related local species, resulting in hybrids like the Africanized honey bee which are hybrids of European Bees and the more aggressive African bees.
Examples of non native pests
There are countless examples of Non Native Pests. Some of these are mentioned below --
- Asian Tiger Mosquitoes arrived in the West accidentally in tires imported from Japan. They pose the same problems as all mosquitoes, serving as hosts to a variety of diseases.
- The Tropical Soda Apple is otherwise known as the “Weed from Hell”. This native of Argentina and Brazil, is prickly and thorny and very aggressive, has about 400 seed per fruit, and is readily transferred from one place to another on animal fur and in droppings. Controls other than herbicides and cutting do not yet exist, and it has destroyed acres of land in the US.
- Kudzu, a native to Japan, Asia and China, was introduced in the US in the 1870's as a grazing crop, and ornamental vine. Its use was encouraged as an erosion control measure. However, it began growing at an uncontrollable rate and became a serious environmental threat. It has destroyed forest and crop lands, dismantled fences, encroached on roads and bridges, and threatened power lines in the US.
- Hydrilla was introduced into the US in the 1960's when it was dumped from aquariums into waterways. Native to Europe, Asia, and Africa, the plant grew exponentially in the US, choking its waterbodies. This plant has been linked to several drowning deaths in the United States, and is a problem for recreational boating, water sports and swimming.
- The Rhododendron, an ornamental flowering shrub, has invaded Britain’s woods and heath land from the Iberian Peninsula. It out-shades native plants and is causing problems in many important oak and hazel wood lands on the west coast of Scotland.
Think about it, human beings are probably the most dangerous Non Native Pests of them all, since they have the capacity to alter and destroy everything, including themselves!