Who’s Afraid of Giant African Snails? Maybe We Shouldn’t

this Giant African snail The snail is the poster child for a global epidemic: the threat of invasive species. It is native to coastal East Africa but is now found across Asia, the Pacific, and the Americas—in fact, on nearly every tropical continent and island except Australia.

Despite their notoriety, our research An investigation into Christmas Island’s invasive snail population suggests the threat they pose to the local ecosystem has been greatly exaggerated.

The giant African snail certainly has the classic traits of a successful invader: They can thrive in many different places; they feed on a wide range of foods; they reach reproductive age quickly; and they lay more than 1,000 eggs in their lifetime. Add all that together, and you have a species that is widely recognized as a One of the worst invaders in the world.

Snails can be eaten Hundreds of plant speciesIncluding vegetable crops (even calcium-rich Plaster and stucco) and is described as Major Threats agriculture.

They have Stopped at Australian portthe Ministry for Primary Industries agrees that snails are “serious threat”.

despite this, No specific research has been done on its impact on the environment. Some Researchers Some argue that the risk to agriculture is exaggerated by reports of damage to gardens. There have been no reports of giant African snails damaging natural ecosystems.

Quietly eating fallen leaves

In a recent study published in the journal Southern EcologyWe tested these hypotheses by investigating giant African snails living in the African rainforests. Christmas Island.

The giant African snail has spread across Christmas Island, helped by another invasive species: Yellow Crazy Ant.

Before these ants appeared, the abundant native Red Land Crab The giant snail was eaten before it could gain a foothold in the rainforest. Unfortunately, the yellow crazy ants Completely eliminate crabs In some areas of the island, the snails thrive.

We predicted that the broad range of snail food would have a significant impact on leaf litter and seedling survival.

However, our evidence simply does not support this idea. Using several different methods – including field trials, laboratory experiments and observational studies – we found that giant African snails largely ate only a few dead leaves and little else.

We could barely tell the difference between leaf litter that the snails had removed and leaf litter that had naturally decomposed. They would eat the leaf litter, but not much.

We saw almost no impact on seedling survival, and almost never saw snails eating live leaves. In one lab trial, we tried feeding snails only fresh leaves, but so many of them died that we had to end the experiment early. Perhaps the common plants on Christmas Island are just not tasty.

Giant African snails may also cause other problems on Christmas Island. In Florida, for example, they Carrying parasites that are harmful to human healthBut for the key ecological processes we study, the snails are not causing the kind of disruption we might think because of their large numbers.

The assumption that the giant African snail is dangerous to local plants and agriculture comes from an overriding sentiment that Invasive species are destructive and must be controlled.

Do we have reliable data on the ecological impacts of all invasive species? Of course not. Should we still try to control all large invasive species, even if there is no evidence that they cause harm? This is a more difficult question to answer.

this Precautionary Principle This drives much of the thinking behind the management of invasive species, including the giant African snail. The cost of inaction can be very high, so the safest approach is to assume that invasive species are having an impact (especially when they are present in large numbers).

But we should also work to test these hypotheses. Proper monitoring and experimentation allow us to truly understand The risks of taking action (or not taking action).

In fact, the giant African snail is more like a poster child for our knee-jerk reaction to large numbers of invaders.