25 - Invasive species RNR 2031

Invasive species

Non-native, undesirable, rapidly expanding plants, animals, and pathogens. With modern globalization, invasive species can be transported anywhere in the world overnight.

Damage and control costs

The annual cost of damage and control of invasive species in the United States, which approaches $150 billion.

Characteristics of invasive species

Traits that make invasive species successful, including filling empty niches, having few or no natural predators, rapid reproduction, the ability to outcompete native species, and high dispersal ability.

Intentional introductions

The deliberate movement of species by humans (since domestication (9000 BC) for various purposes, such as food (early times as well as now), work/utility, companionship, economic value, aesthetics, and biological control.

Cane toad

Native to Central and South America.
Can grow to 15” in size and weigh 6 lbs
Toxic skin; tadpoles are highly toxic when ingested by predators

Cane toad introductions

The intentional introduction of cane toads to Puerto Rico in the 1930s to control beetles ravaging sugarcane plantations, which later spread throughout northern Australia.
Hailed as a miraculous means of biological control!

Cane toads in Australia

Introduced sugar cane in the late 1800s as a cash crop
Increasing crop damage caused by the native Grey-backed Cane Beetle and Frenchi Beetle
Released 102 cane toads in northeastern Australia in 1935

By early 2000s they spread throughout northern Australia

Ecological impacts of Cane Toads

Lack predators that can deal with the poisonous toad; Evolution!
Massive declines in native species such as the northern quoll, freshwater crocodile, and Argus monitor

Ecological impacts of Cane toads

The negative effects of invasive species on native species and ecosystems, including declines in native species and disruption of ecological balance.

Social and economic impacts of Cane toads

The adverse effects of invasive species on society and the economy, such as toxicity to pets and children, public nuisance, and potential economic losses.

Nutria

A species native to South America with phenomenal reproductive capabilities:
Mature at 6 months, an produce a litter of up to 13 three times a year and at any given time, 65% of females are pregnant.

Consume 25% of their body weight daily, eating both above and belowground biomass of aquatic vegetation

Nutria invasion

The introduction of nutria to Louisiana in the 1930s for their value as a furbearer, leading to people letting them lose due to not being profitable and the rest escaping and then the subsequent damage to wetlands.

Nutria control and impacts

Herbivory damage to LA wetlands totaled >100,000 acres in 1998
Well-funded bounty program established, reducing damage to 8,000 acres during the 2020-2021 season.
$4 (now $6) per nutria tail attempts to create a market for nutria meat, such as Marsh Dog biscuits made from nutria.

European Starling

A bird species native to temperate Europe and western Asia, introduced to North America; along with other 60 bird species released into Central Park by Eugene Schieffelin, head of the American Acclimatization Society.

Starlings today

More than 200 million throughout North America
Vicious competitors for nest cavities, outcompeting swallows, bluebirds, etc.

Accidental introductions

The unintentional introduction of invasive species through various means, such as transportation methods, including boats, planes, and hiking boots, as well as through the movement of other animals, produce, firewood, and flowers.

Brown Tree Snake

A snake species native to Australia, New Guinea, and adjacent islands. Arrived in Guam as a stowaway in military cargo or landing gear in the late 1940s with severe consequences for avian and reptile species.

Ecological and social impacts of Brown Tree Snakes

A lot of avian extinctions and as a result a lot of native plant species were not dispersed causing many species to be eliminated.

With no natural predators and an abundant naïve prey base, snake numbers grew to over 2 million from 1940s - 1970s.
Problems with snakes shorting out power lines.
Concern about venomous bites to children.

Controlling the Brown Tree Snake

Methods used to control and manage the population of the Brown Tree Snake, including barriers, trapping, chemical, and biological control.

Zebra mussels

Invasive mussels native to Russia, introduced to the Great Lakes through ballast tanks in 1985 and spread through river connections, causing economic and ecological consequences.

Ecological and social impacts of Zebra mussels

• Serious economic consequences - foul marine equipment and pipelines, densities as high as 750,000 mussels/m²

• Overwhelm other benthic species

• Alter water clarity and ecosystem ecology

• Concentrate toxins; bioaccumulation in predators

Spongy moths

Formerly known as Gypsy moths, invasive moths native to Europe that have caused significant defoliation and economic and ecological impacts in the United States.

Ecological and economic impacts of spongy moths

Responsible for defoliating more than 80 million acres since 1970. Economic impacts on valuable trees ($ billons). Ecological impacts on forest-dependent species, especially birds.

Control options for spongy moths

Strategies used to control spongy moth populations, including monitoring, pheromone flakes, viral insecticides, and bacterial insecticides.