Page 41 - Fourways Gardens March 2021

Nature

One of the largest terrestrial gastropods, the Giant African Land
Snail (Achatina fulica) hails from East Africa and its natural habitat
stretches all the way from the north-eastern region of Kwazulu
Natal through Mozambique, Tanzania and Kenya to Somalia and
Ethiopia. It has an average lifespan of 5 – 7 years, although it can
live longer in ideal conditions. This snail can grow up to 20cm in
length and its shell can extend up to 7cm in height. When it is
fully grown, its shell will have between 7 and 9 spirals, which are
normally dark or medium brown with stripes at intervals.

Although classified as hermaphrodites, (having both male and
female sex organs), reproduction requires cross-fertilisation.
Mating involves both a ‘getting to know each other phase’ and
copulation which normally takes place at night. From a single Little achatina BY TIMUR V. VORONKOV
mating, the individual that received the sperm can produce
batches of fertilised eggs over a period of months, although the
sperm can also be stored by the snail for up to two years before
fertilising any eggs.

Between 100 and 500 eggs are laid at a time. The eggs hatch one
to three weeks later and the baby snails reach sexual maturity five
to eight months after hatching. And that’s how a plague of Giant
African Land Snails can develop in a relatively short period of time.

The Giant African Land Snail is now found on every continent
around the globe (except for Antarctica). Apart from being
smuggled across borders by exotic pet traders, it is transported
over large distances via cargoes of agricultural products and,
as it can survive in a state of aestivation (dormancy to avoid
excessive heat and dryness) for years, just as authorities declare
that they have the infestation under control, when weather Achatina fulica eggs BY KEN WALKER, MUSEUM VICTORIA
conditions improve, out they pop again.

WHY ARE THEY SUCH A THREAT TO HUMANS AND THE
ENVIRONMENT?
• They are voracious feeders, consuming around 500 different
species of plants. Not only do they climb into and devastate
agricultural crops such as coffee, cocoa and rubber plantations,
they also love fruit, vegetables, nuts and grains. They are known
to eat the bark and stems of trees, seaweed, lichens, fungi and
even other snails.
• Because they need calcium for their shells, they are capable of
eating the plaster off buildings, as well as sand, concrete and
even bones.
• They are hosts to a number of parasites, including Angiostrongylus Giant African Land Snail (Achatina fulica) in Hyderabad.
cantonensis, a nematode (roundworm) that causes eosinophilic Opposite page: Achatina fulica seen in a suburban garden in Johannesburg.
meningoencephalitis in humans.
• Although this has not been discussed in any of the research
HOW CAN ONE ERADICATE AND DISPOSE OF THEM? material available, speaking as a true South African male, I
• The first message here comes across loudly and clearly – DO would suggest incinerating them along with any eggs that you
NOT SIMPLY THROW THEM IN YOUR RUBBISH DESTINED FOR find. And then burying the ash under a reasonable layer of soil
LANDFILL! in a corner of the garden.
• Spraying them with vinegar is suggested, or sprinkling them
with Diatomaceous earth could be a solution. Whatever you do, with the Giant African Land Snail featuring
• Surround your plants with rings of wheat bran or corn bran – prominently on the list of Top 100 Most Invasive Species in the
you can buy these products from health food stores. They are World, it’s recommended that the handling (using suitable
eaten by slugs and snails and the ingested bran then causes gloves and other protection) and disposal of these ‘cute snails
desiccation and death. This is a totally organic solution, and on steroids’ should be done with caution.
if wildlife eat the corpses, they are getting extra nutrition. Resources:
However, you need to replenish the bran regularly in rainy www.aphis.usda.gov
www.cabi.org
weather. www.biokids.umichu.edu

Fourways Gardens • 39 • March 2021