The recent talk adout feral cats got me wondering. Worldwide, which invasive species has had the most catastrophic ecological effect?

“An invasive species is a plant, fungus, or animal species that is not native to a specific location (an introduced species), and that has a tendency to spread to a degree believed to cause damage to the environment, human economy or human health.”

There are plenty of candidates for ecological catastrophe caused by an invasive species. Notable ivasive species include:

Chestnut blight, dutch elm disease, crayfish plague, banana bunchy top virus, chytrid frog fungi, killer algae, avian malaria,

Redback spider, white tail spider, tiger mosquito, malaria mosquito, yellow crazy ant, asian longhorned beetle, cotton whitefly, fishhook waterflea, cypress aphid, formosa termite, argentine ant, gypsy moth, big headed ant, new guinea flatworm, fire ant, european wasp

Kudzu, pampas grass, yellow starthistle, skeleton weed, water hyacinth, invasive lawn grasses, lantana, blackberry, barbed goatgrass, diffuse knapweed, cheatgrass, smooth cordgrass, gorse, black wattle, shoebutton ardisia, giant cane, trumpet tree, siam weed, cinchona, koster’s curse, leafy spurge, japanese knotweed, ginger lily, hiptage, white leadtree, privet, loosestrife, paperbark teatree, bush currant, mile-a-minute, sensitive mimosa, prickly pear, salvinia,

Pacific sea star, european fanworm, zebra mussel, chinese mitten crab, european green crab, cannibal snail, giant african land snail, sea walnut, apple snail,

Carp, sea lamprey, silver carp, walking catfish, mosquito fish, nile perch, largemouth bass, rainbow trout, tilapia, brown trout,

Cane toad, brown tree snake, burmese python, giant chinese salamander, caribbean tree frog, american bullfrog,

Rabbit, cat, dog, black rat, brown rat, red deer, camel, wild boar, brushtail, mongoose, ferret, water buffalo, grey squirrel, beaver, pacific rat, goat, crab-eating macaque, stoat, fox,

Sparrow, pigeon, rainbow lorikeet, cockatoo, myna, red-vented bulbul,

Which of these is/are the worst?

mollwollfumble said:

The recent talk adout feral cats got me wondering. Worldwide, which invasive species has had the most catastrophic ecological effect?

“An invasive species is a plant, fungus, or animal species that is not native to a specific location (an introduced species), and that has a tendency to spread to a degree believed to cause damage to the environment, human economy or human health.”

There are plenty of candidates for ecological catastrophe caused by an invasive species. Notable ivasive species include:

Chestnut blight, dutch elm disease, crayfish plague, banana bunchy top virus, chytrid frog fungi, killer algae, avian malaria,

Redback spider, white tail spider, tiger mosquito, malaria mosquito, yellow crazy ant, asian longhorned beetle, cotton whitefly, fishhook waterflea, cypress aphid, formosa termite, argentine ant, gypsy moth, big headed ant, new guinea flatworm, fire ant, european wasp

Kudzu, pampas grass, yellow starthistle, skeleton weed, water hyacinth, invasive lawn grasses, lantana, blackberry, barbed goatgrass, diffuse knapweed, cheatgrass, smooth cordgrass, gorse, black wattle, shoebutton ardisia, giant cane, trumpet tree, siam weed, cinchona, koster’s curse, leafy spurge, japanese knotweed, ginger lily, hiptage, white leadtree, privet, loosestrife, paperbark teatree, bush currant, mile-a-minute, sensitive mimosa, prickly pear, salvinia,

Pacific sea star, european fanworm, zebra mussel, chinese mitten crab, european green crab, cannibal snail, giant african land snail, sea walnut, apple snail,

Carp, sea lamprey, silver carp, walking catfish, mosquito fish, nile perch, largemouth bass, rainbow trout, tilapia, brown trout,

Cane toad, brown tree snake, burmese python, giant chinese salamander, caribbean tree frog, american bullfrog,

Rabbit, cat, dog, black rat, brown rat, red deer, camel, wild boar, brushtail, mongoose, ferret, water buffalo, grey squirrel, beaver, pacific rat, goat, crab-eating macaque, stoat, fox,

Sparrow, pigeon, rainbow lorikeet, cockatoo, myna, red-vented bulbul,

Which of these is/are the worst?

Humans :P.

Because Australia had such a large percentage of animals that fall into the prey sizes affected by cats and they have had populations so reduced and many facing extinction I would say the cat in Australia has had the most impact on the existing animal species.

> Humans :P.

Sorry. I meant to specifically exclude humans and stock in the OP. I forgot.

The feral species who has the greatest negative impact on human health worldwide is easier to determine. Dogs. Rabies currently kills 59,000 people per year.

Pest with the greatest negative impact on agriculture. There are several answers, not all are invasive: from http://www.bbc.com/news/science-environment-15623490

Desert locust – Worst historical pest.
South american rubber blight – Hardest pest to control.
Western corn root worm – Most expensive to control.
Potato blight – Worst human impact.
Khapra beetle – Worst stored product pest (I have it inside my house).
Mountain pine beetle – Greatest climate change.
Wheat stem rust strain Ug99 – Most imminent threat.
Colorado potato beetle – Most resilient pest.

There would probably be several different categories of “most catastrophic ecological effect” such as number of species driven to extinction (probably on oceanic islands), greatest population pressure, greatest number of native animals killed, greatest area driven sterile.

AwesomeO said:

Because Australia had such a large percentage of animals that fall into the prey sizes affected by cats and they have had populations so reduced and many facing extinction I would say the cat in Australia has had the most impact on the existing animal species.

That makes sense. Not just in Australia either. “Globally, it is estimated that there are 100 million or more feral cats with at least 60 million living in the US”.

Mosquitoes ?

Over one million people die from malaria each year, mostly children under five years of age, with 90 per cent of malaria cases occurring in Sub-Saharan Africa. An estimated 300-600 million people suffer from malaria each year. More than 40 percent of the world’s population lives in malaria-risk areas.

Fruit fly damage to fruit not just damage to the fruit but costs to control/limit the damage

Cymek said:

Mosquitoes ?

Over one million people die from malaria each year, mostly children under five years of age, with 90 per cent of malaria cases occurring in Sub-Saharan Africa. An estimated 300-600 million people suffer from malaria each year. More than 40 percent of the world’s population lives in malaria-risk areas.

Fruit fly damage to fruit not just damage to the fruit but costs to control/limit the damage

You’re right. The common malaria mosquito is an invasive species. I hadn’t realised that.

Ditto the fruit fly. Well spotted.

mollwollfumble said:

The feral species who has the greatest negative impact on human health worldwide is easier to determine. Dogs. Rabies currently kills 59,000 people per year.

Pest with the greatest negative impact on agriculture. There are several answers, not all are invasive: from http://www.bbc.com/news/science-environment-15623490

Desert locust – Worst historical pest.
South american rubber blight – Hardest pest to control.
Western corn root worm – Most expensive to control.
Potato blight – Worst human impact.
Khapra beetle – Worst stored product pest (I have it inside my house).
Mountain pine beetle – Greatest climate change.
Wheat stem rust strain Ug99 – Most imminent threat.
Colorado potato beetle – Most resilient pest.

There would probably be several different categories of “most catastrophic ecological effect” such as number of species driven to extinction (probably on oceanic islands), greatest population pressure, greatest number of native animals killed, greatest area driven sterile.

AwesomeO said:

Because Australia had such a large percentage of animals that fall into the prey sizes affected by cats and they have had populations so reduced and many facing extinction I would say the cat in Australia has had the most impact on the existing animal species.

That makes sense. Not just in Australia either. “Globally, it is estimated that there are 100 million or more feral cats with at least 60 million living in the US”.

In “List of recently extinct mammals” it’s noted that introduced species on continents never cause extinctions, with the notable exception of cats in Australia. The normal causes of extinction are hunting, agriculture, logging and disease.

This wouldn’t be true of island flora and fauna. Introduced species there can cause extinctions.

mollwollfumble said:

mollwollfumble said:

The feral species who has the greatest negative impact on human health worldwide is easier to determine. Dogs. Rabies currently kills 59,000 people per year.

Pest with the greatest negative impact on agriculture. There are several answers, not all are invasive: from http://www.bbc.com/news/science-environment-15623490

Desert locust – Worst historical pest.
South american rubber blight – Hardest pest to control.
Western corn root worm – Most expensive to control.
Potato blight – Worst human impact.
Khapra beetle – Worst stored product pest (I have it inside my house).
Mountain pine beetle – Greatest climate change.
Wheat stem rust strain Ug99 – Most imminent threat.
Colorado potato beetle – Most resilient pest.

There would probably be several different categories of “most catastrophic ecological effect” such as number of species driven to extinction (probably on oceanic islands), greatest population pressure, greatest number of native animals killed, greatest area driven sterile.

AwesomeO said:

Because Australia had such a large percentage of animals that fall into the prey sizes affected by cats and they have had populations so reduced and many facing extinction I would say the cat in Australia has had the most impact on the existing animal species.

That makes sense. Not just in Australia either. “Globally, it is estimated that there are 100 million or more feral cats with at least 60 million living in the US”.

In “List of recently extinct mammals” it’s noted that introduced species on continents never cause extinctions, with the notable exception of cats in Australia. The normal causes of extinction are hunting, agriculture, logging and disease.

This wouldn’t be true of island flora and fauna. Introduced species there can cause extinctions.

Australia is an island and the wildlife had not seen a predator like th cat before.

roughbarked said:

mollwollfumble said:

mollwollfumble said:

The feral species who has the greatest negative impact on human health worldwide is easier to determine. Dogs. Rabies currently kills 59,000 people per year.

Pest with the greatest negative impact on agriculture. There are several answers, not all are invasive: from http://www.bbc.com/news/science-environment-15623490

Desert locust – Worst historical pest.
South american rubber blight – Hardest pest to control.
Western corn root worm – Most expensive to control.
Potato blight – Worst human impact.
Khapra beetle – Worst stored product pest (I have it inside my house).
Mountain pine beetle – Greatest climate change.
Wheat stem rust strain Ug99 – Most imminent threat.
Colorado potato beetle – Most resilient pest.

There would probably be several different categories of “most catastrophic ecological effect” such as number of species driven to extinction (probably on oceanic islands), greatest population pressure, greatest number of native animals killed, greatest area driven sterile.

That makes sense. Not just in Australia either. “Globally, it is estimated that there are 100 million or more feral cats with at least 60 million living in the US”.

In “List of recently extinct mammals” it’s noted that introduced species on continents never cause extinctions, with the notable exception of cats in Australia. The normal causes of extinction are hunting, agriculture, logging and disease.

This wouldn’t be true of island flora and fauna. Introduced species there can cause extinctions.

Australia is an island and the wildlife had not seen a predator like th cat before.

And especially not one that can breed like cats

roughbarked said:

mollwollfumble said:

mollwollfumble said:

The feral species who has the greatest negative impact on human health worldwide is easier to determine. Dogs. Rabies currently kills 59,000 people per year.

Pest with the greatest negative impact on agriculture. There are several answers, not all are invasive: from http://www.bbc.com/news/science-environment-15623490

Desert locust – Worst historical pest.
South american rubber blight – Hardest pest to control.
Western corn root worm – Most expensive to control.
Potato blight – Worst human impact.
Khapra beetle – Worst stored product pest (I have it inside my house).
Mountain pine beetle – Greatest climate change.
Wheat stem rust strain Ug99 – Most imminent threat.
Colorado potato beetle – Most resilient pest.

There would probably be several different categories of “most catastrophic ecological effect” such as number of species driven to extinction (probably on oceanic islands), greatest population pressure, greatest number of native animals killed, greatest area driven sterile.

That makes sense. Not just in Australia either. “Globally, it is estimated that there are 100 million or more feral cats with at least 60 million living in the US”.

In “List of recently extinct mammals” it’s noted that introduced species on continents never cause extinctions, with the notable exception of cats in Australia. The normal causes of extinction are hunting, agriculture, logging and disease.

This wouldn’t be true of island flora and fauna. Introduced species there can cause extinctions.

Australia is an island and the wildlife had not seen a predator like th cat before.

I just found that there is a searchable “Global Invasive Species Database” on http://www.iucngisd.org/gisd/

It has a link to “100 of the World’s Worst Invasive Alien Species” on http://www.iucngisd.org/gisd/100_worst.php

Interestingly, one of the previously listed 100 worst, rinderpest, is now extinct in the wild, replaced on the list by salvinia.

Along with the cat, “The ship rat is most frequently identified with catastrophic declines of birds on islands.”

About rinderpest, may be wrong but I believe that was only an issue with imported domestic cattle and horses, so maybe still around in the wild but we have learned to not try and stock areas infected with it.

The Hydatid tapeworm is a good reason not to have a dog.

Looking through that list of 100 worst.

The clear worst invasive species from the viewpoint of number of species driven extinct is the Nile Perch.

The Nile perch (Lates niloticus) is a large freshwater fish. Also known as capitaine, mputa or sangara, it can grow up to 200kg and two metres in length. It was introduced to Lake Victoria in 1954 where it has contributed to the extinction of more than 200 endemic fish species through predation and competition for food.

It’s far from clear which is second worst in terms of number of species driven extinct (feral cats in Australia have driven at least one bird species extinct).

One to watch out for is the brown tree snake. But the iucn redlist has only 3 extinct species in Guam and a further 2 “extinct in the wild”.

Native island species are predisposed and vulnerable to local extinction by invaders. When the brown tree snake (Boiga irregularis) was accidentally introduced to Guam it caused the local extinction of most of the island’s native bird and lizard species. It also caused cascading ecological effects by removing native pollinators, causing the subsequent decline of native plant species. The ecosystem fragility of other Pacific islands to which cargo flows from Guam has made the potential spread of the brown tree snake from Guam a major concern.

“The Academy Award-nominated documentary Darwin’s Nightmare by Hubert Sauper (a French-Austrian-Belgian production, 2004) deals with the damage that has been caused by Nile Perch introduction, including the import of weapons and ammunition in cargo planes from Europe, which are then used to export Nile perch, further exacerbating conflict and misery in the surrounding regions.”

“The state of Queensland in Australia levies heavy fines on anyone found in possession of a living Nile perch, since it competes directly with the native barramundi, which is similar.”

mollwollfumble said:

“The Academy Award-nominated documentary Darwin’s Nightmare by Hubert Sauper (a French-Austrian-Belgian production, 2004) deals with the damage that has been caused by Nile Perch introduction, including the import of weapons and ammunition in cargo planes from Europe, which are then used to export Nile perch, further exacerbating conflict and misery in the surrounding regions.”

“The state of Queensland in Australia levies heavy fines on anyone found in possession of a living Nile perch, since it competes directly with the native barramundi, which is similar.”

Well that is interesting, maybe the Lake Victoria crocodiles are not interested in the Perch?

AwesomeO said:

mollwollfumble said:

“The Academy Award-nominated documentary Darwin’s Nightmare by Hubert Sauper (a French-Austrian-Belgian production, 2004) deals with the damage that has been caused by Nile Perch introduction, including the import of weapons and ammunition in cargo planes from Europe, which are then used to export Nile perch, further exacerbating conflict and misery in the surrounding regions.”

“The state of Queensland in Australia levies heavy fines on anyone found in possession of a living Nile perch, since it competes directly with the native barramundi, which is similar.”

Well that is interesting, maybe the Lake Victoria crocodiles are not interested in the Perch?

they are into pasta now…

AwesomeO said:

mollwollfumble said:

“The Academy Award-nominated documentary Darwin’s Nightmare by Hubert Sauper (a French-Austrian-Belgian production, 2004) deals with the damage that has been caused by Nile Perch introduction, including the import of weapons and ammunition in cargo planes from Europe, which are then used to export Nile perch, further exacerbating conflict and misery in the surrounding regions.”

“The state of Queensland in Australia levies heavy fines on anyone found in possession of a living Nile perch, since it competes directly with the native barramundi, which is similar.”

Well that is interesting, maybe the Lake Victoria crocodiles are not interested in the Perch?

> they are into pasta now…

Crocodiles. I’d forgotten that.

“The fisher-folk of East Africa’s largest fresh water lake, Lake Victoria are now becoming prey in the same waters they draw fish from. Crocodile attacks have increasingly made fishing a life threatening activity. More than 15 people have been killed by crocodiles in Lake Victoria since 2013.”

mollwollfumble said:

“The Academy Award-nominated documentary Darwin’s Nightmare by Hubert Sauper (a French-Austrian-Belgian production, 2004) deals with the damage that has been caused by Nile Perch introduction, including the import of weapons and ammunition in cargo planes from Europe, which are then used to export Nile perch, further exacerbating conflict and misery in the surrounding regions.”

“The state of Queensland in Australia levies heavy fines on anyone found in possession of a living Nile perch, since it competes directly with the native barramundi, which is similar.”

What about its effect upon the Murray Cod. Doesn’t it also belong to the Percichthyidae?

mollwollfumble said:

AwesomeO said:

mollwollfumble said:

“The Academy Award-nominated documentary Darwin’s Nightmare by Hubert Sauper (a French-Austrian-Belgian production, 2004) deals with the damage that has been caused by Nile Perch introduction, including the import of weapons and ammunition in cargo planes from Europe, which are then used to export Nile perch, further exacerbating conflict and misery in the surrounding regions.”

“The state of Queensland in Australia levies heavy fines on anyone found in possession of a living Nile perch, since it competes directly with the native barramundi, which is similar.”

Well that is interesting, maybe the Lake Victoria crocodiles are not interested in the Perch?

> they are into pasta now…

Crocodiles. I’d forgotten that.

“The fisher-folk of East Africa’s largest fresh water lake, Lake Victoria are now becoming prey in the same waters they draw fish from. Crocodile attacks have increasingly made fishing a life threatening activity. More than 15 people have been killed by crocodiles in Lake Victoria since 2013.”

That would be from increasing population. The reason why I was wondering about the lake Victoria crocodiles is because absolutely everything eats Barramundi even when it gets big but after a certain size it’s only crocodiles thst can take them on, but the perch don’t seem to have that. And as I was typing that, I was thinking sharks as well.

mollwollfumble said:

AwesomeO said:

mollwollfumble said:

“The Academy Award-nominated documentary Darwin’s Nightmare by Hubert Sauper (a French-Austrian-Belgian production, 2004) deals with the damage that has been caused by Nile Perch introduction, including the import of weapons and ammunition in cargo planes from Europe, which are then used to export Nile perch, further exacerbating conflict and misery in the surrounding regions.”

“The state of Queensland in Australia levies heavy fines on anyone found in possession of a living Nile perch, since it competes directly with the native barramundi, which is similar.”

Well that is interesting, maybe the Lake Victoria crocodiles are not interested in the Perch?

> they are into pasta now…

Crocodiles. I’d forgotten that.

“The fisher-folk of East Africa’s largest fresh water lake, Lake Victoria are now becoming prey in the same waters they draw fish from. Crocodile attacks have increasingly made fishing a life threatening activity. More than 15 people have been killed by crocodiles in Lake Victoria since 2013.”

The reason is probably that there are not enough fish for the crocodiles to eat.