Prepare to be Invaded!, or A Quick Study on Invasive Organisms What does it mean to be “invasive”? 1) Exotic (not endemic, or native to an area) But that is simply not enough…

2) Able to survive and reproduce in the new area. -a distinct breeding population, more than just a few random individuals But this is STILL not enough!

3) The population needs to take over another populations niche, or force it out. -Invasives often become a mono- culture, and wreck the ecosystem. -Loss of diversity, loss of habitat, loss of food for other organisms, etc..

Things most invasive species have in common: 3) Have characteristics that exclude native species from a habitat. 2) Usually very prolific, reproducing very rapidly. 1) No natural predators, so nothing to hold the population down.

Some Quick Numbers: $137 BILLION dollars in damage due to invasives every year. 50,000 exotic species (estimated) are released in the US every year. But there is some GOOD news!

The 10% Rule Only 10% of introduced exotics will live at all. -Wrong climate, food availability, etc.. Of the 10% that live, only 10% will actually be able to breed and become invasive. -You need to find a mate and the proper conditions to raise young.

Invasive Organisms in Delaware -There are a number of invasive, non- native organisms that have made Delaware their home. Below is a sample of some of the most invasive, some of which you might think are native organisms.

1) Kudzu vine -Native of Asia, brought to the U.S. to control erosion along river banks and new ditches -infests 2-3 million acres in eastern U.S., with an annual loss of over $50 million due to lost productivity, and cost of control.

2) Nutria: -small wetland mammal, brought from South America for its fur. The fur trade never really took off, now it’s a very bad pest in wetlands. -it eats young shoots and roots, killing marsh plants, destroying wetlands

3) Multiflora Rose: -Native to Asia, brought to U.S. from Japan in the 1800’s. -Used to control erosion along rivers and act as a “living fence”. -Forms dense thickets, crowds out native plants and animals. -Very prolific breeder, makes many seeds, can grow just about anywhere.

4) Gypsy Moth: -introduced to this country from Asia in 1868, accidentally. -voracious eaters, especially fond of oak trees. -is responsible for the general decline in numbers of oaks in forests over the past 100 years.

5) Purple Loosetrife: -Native to Europe/Asia -Introduced in the 1800’s to U.S. -wetland plant, very aggressive competitor for land, nutrients. -crowds out native reeds, cattails. -extremely prolific, one plant can produce over 30,000 seeds.

6) Honeysuckle: -Imported from Japan in 1862 to Long Island, N.Y. -Very tenacious vine, covers and pulls down large trees and shrubs -Often grows in disturbed areas, such as roadsides, and along edges of forests.

7) European Green Crab -Native to Africa/Europe -tolerates a wide variety of conditions -eats many more clams/mussels than native crabs, causing a decrease in numbers of clams. -pushes many other crabs out of the habitat, and takes over (aggressive).

NATIVE Calico Crab INVASIVE European Green Crab

8) Mute Swan: -Native to Europe -introduced to U.S. by European admirers, has shown a great population increase since introduction. -very aggressive, competes with native waterfowl for food and breeding space. -is taking over in many places.

Introduced in 1890 as part of a plan to introduce to the U.S. all birds mentioned in the works of Shakespeare. (12 birds released) 9) European Starling Very aggressive, pushes native song birds away From feeders and nesting areas. Highly prolific, they breed in conditions that other birds cannot, and so have a high population. (Estimated at over 200 million in the U.S.)

Introduced accidentally into New Jersey from Japan in 1916 and is now widespread over the eastern United States. 10) Japanese Beetles Both the grub and the adult are voracious eaters, and cause widespread damage to trees, shrubs, and grass.

Introduction of Invasive Species 1) Intentional Introduction -for economic purposes (Ex: nutria) -for cultural purposes (Ex: starlings, Asian Shore crabs) -for misguided environmental projects (Kudzu, Multiflora rose) -for aesthetic reasons (Honeysuckle, Purple Loosestrife

2) Accidental Release -Ballast water transfer from foreign areas (Green crab, Zebra Mussel, Comb Jellyfish) -Accidental release of organisms (gypsy moth, “Killer” African bees -Transfer in packing material (European Green Crab to California, Horned Asian Beetle)

Control of Invasives Much of the control of invasive pests relies on the ability to lower the population early on, before the size has grown beyond our capability to handle it. -Once the population has a “foothold”, it is much harder, if not impossible to eliminate.

Control vs. Eradication -Is the cure better than the problem? -economics and environmental damage play a role in deciding to eradicate an invasive. It may not always be in our best interests to completely eliminate a population of pests.

Past a certain point, eradication will be virtually impossible in any case. Usually, by the time the pest is noticed, the ability to eradicate it has been lost. -Especially in marine ecosystems, because of the ability of the organism to go without being noticed until large numbers exist. This makes a good case for close monitoring of critical habitat.

Control of Invasives Point of First Discovery Ability to Control is lost Time (months) Population Size

Success of control depends on a few key factors: 1)Catching the infestation EARLY, before population numbers get out of hand. 2) Whether or not the invasive organism is mobile within the environment. 3) How rapidly the invasive can reproduce. -does it reproduce in more than one way? -does it need certain conditions? 4) How vulnerable the invasive is to control. -is it tolerant to pesticides? -will it re-grow if burned?

Control Methods can include: Control Methods 5) Chemical management 4) Biological management 3) Cultural management 2) Physical (manual & mechanical) management 1) No action. This alternative may be chosen if the pest numbers are low enough that they don't interfere with management goals

Mechanical or Physical Management: Mechanical or physical control methods involve using barriers, traps, or physical removal to prevent or reduce pest problems. Tactics may include baited or pheromone traps to capture insects, or cultivation or mowing for weed control.

Cultural management: Cultural practices are a manipulation of the habitat environment to increase pest mortality or reduce rates of pest increase and damage. There are many different cultural practices that can help to reduce pest impact such as selection of pest resistant varieties of crops, mulching, addition of beneficial insect habitat, or other habitat alterations.

Biological Management: Biological control is the deliberate use of the pest's natural enemies - predators, parasites, and pathogens - to reduce the pest population below damage levels.

Purple Loosestrife: A Study in Biological Control

Purple loosestrife is a difficult plant to kill with conventional weed killers because it grows near bodies of water. Week killers used on the invasive plants could end up in the waterways, and cause more damage to fragile aquatic organisms. Scientists went back to the origin of the plant and looked for insects that ate ONLY loosestrife.

Three beetle species have been grown and released in parts of the U.S. since Two of these species feed as both adults and immature larvae on the leaves and growing tips. The most promising beetle is Galerucella calmariensis.

They have one generation per year and overwinter as adults. Eggs are laid in clusters of 5-20 on the leaf surface, often where the leaf joins the stem. The feeding causes holes in the leaves, reducing the amount of leaf area, weakening the plant. Also, larvae feed in the growing tips, which can reduce or prevent flowering -- and no flowers means no seeds.

Before the insects were allowed into the U.S. in the early 1990s, they were tested against 49 species of plants to determine on which ones what they would feed. When they were given a simultaneous choice of purple loosestrife or the native species, the beetles fed very little on the two native species, but did NOT lay eggs on them -- meaning there would be no damage from larval feeding and no new generation of beetles on these species of plants.

There are no guarantees of success, but there are several beginning signs of promise. At one site near Savanna, Illinois, (on the Mississippi River), a total of 1,000 Galerucella beetles were released at three discrete places in In the summer of 1997, there was severe damage to the loosestrife -- many hundreds of dead plants, many thousands more that did not flower, even though other loosestrife in nearby areas was flowering.

From the release of a few hundred Galerucella in 1994, flowering at the site was reduced, by 1997, to only 3% of the plants sampled -- a number small enough that native plants can return to the area.

Chemical Control: Use of pesticides in a way that complements rather than hinders other elements in the strategy and which also limits negative environmental effects. It is important to understand the life cycle of a pest so that the pesticide can be applied when the pest is at its most vulnerable – the aim is to achieve maximum effect at minimum levels of pesticide.

Broad Spectrum vs. Targeted Pesticides A broad spectrum pesticide kills ALL of the related pests. This generally bad because beneficial plants and animals are killed as well. A targeted or NARROW SPECTRUM pesticide is much better for the environment because the beneficial organisms are not harmed.

A Brief Story of Some Invasives The St. Lawrence Seaway is the common name for a system of canals that permits ocean-going vessels to travel from the Atlantic Ocean to the North American Great Lakes, as far as Lake Superior. The Seaway opened in 1959 and cost $470 million US dollars.

The creation of the seaway also led to the introduction of foreign species of aquatic animals, including the sea lamprey, alewife, and the zebra mussel, into the Great Lakes Basin. These organisms were introduced via ballast water from oceanic vessels.

Common Alewife