A citizen army is needed to help tackle invasive species that threaten the natural environment and in some cases human health, MPs have said.

The cost to the economy of non-native species taking hold in the UK is estimated to be £1.8bn a year, a report from the environmental audit committee says.

Among their recommendations, they call for an army of 1.3 million volunteers to be trained across the country to identify and respond to the threat from non-native species, in a scheme modelled on one developed in New Zealand.

The report says urgent action is needed to slow the rate of arrival of invasive species and prevent them from becoming established. It estimates that about 40 non-native species will become invasive within the next 20 years.

The report says ministers have missed the legal targets on tackling invasive species and have failed to give the threat the same priority and funding as animal and plant health regimes.

Current funding for biosecurity in Great Britain is estimated at £220m a year, while invasive species work receives less than 1% of that sum (£0.9m).

Invasive non-native species are those that have been moved as a result of human activity. They are considered one of the top five threats to the natural environment.

Invasive species and their effects currently in the UK include:

An epidemic of ash dieback caused by a non-native fungus, which is predicted to kill half of the UK’s native ash trees, at a cost of £15bn, over the next 100 years.

Signal crayfish, which have been the main cause of the rapid decline in native crayfish through the transmission of crayfish plague.

Xylella on olive imports that can infect more than 350 different plant species and causes symptoms including leaf scorch, wilt, dieback and plant death.

Labour’s Mary Creagh, the chair of the committee, said: “If we’re to beat this, we need people power, with an army of volunteers trained to spot and stop an invasive species before it becomes established.

“We’re witnessing changes, from climate change, that put the future of our natural landscape at risk. Oak processionary moth caterpillars can strip an oak tree bare, as well as posing a hazard to our own health. We face losing half of the UK’s native ash trees to ash dieback within a century, costing £15bn. New regulations to halt their progress are welcome but they are too little, too late. Government funding to tackle invasive species is tiny and fails to match the scale of the threat.”

Richard Benwell, the chief executive of Wildlife and Countryside Link, said: “These invaders can choke out native species, spread disease and strangle industry. Yet the government’s defences against invasive species are decades behind animal and plant health security. It’s time to dedicate the funds and personnel needed to hold the line to defend wildlife.”

The UK has one of the highest numbers of invasive species in the world, MPs on the committee heard in evidence.

A significant increase in the numbers of invasive species across the globe is attributed to a threefold increase in travel and a rise in air and sea transport of goods. The species arrive in the UK in a variety of ways, including by attaching themselves to the hulls of ships or “hitchhiking” within ballast water, as contaminants of ornamental plants, or on fishing equipment.