RESEARCH LETTER 2.9

Cereal killers meet their match

... something a little different from our usual fare ....

This story is about snails and fires, ‘barbequed’ escargot , and cropping problems in Australia’s cereal belt.[1]

Four species of introduced snails pose problems to South Australian (and to some extent Western Australian and Victorian) farmers. Two are “White Snails” and two are “Conical Snails”. Farmers are keen to reduce the impact of these snails which feed on seedlings of wheat, barley and oil seeds, among other crops, occasionally causing total destruction. Stock reject pasture and hay contaminated by the snails. Snails crawl up the mature stems of cereals and lie dormant there during the harvest. They snarl machinery - which I guess is not a pretty sight. They contaminate grain to the extent that exports can be threatened.

Two species of the pest snails are ‘edible’ French snails - ‘ escargot ’ to the gourmet - so available in Australia’s paddocks.  Yes, Theba pisana and Cernuella virgata, two popular table-food species in France, are roaming free in South Australia’s cereal belt (Baker 1986). Don’t rush off just now for a free feed. The taste, palatability, and perhaps toxicity, of such ‘wild’ snails depends on what they have recently eaten. Restaurant snails are cultivated creatures I understand. Although free, it may be best to resist any culinary temptation posed by the Aussie-paddock escargot.

One of the options open to farmers to control the snails is the burning of stubble.  “Burning is very effective at reducing high densities of snails but increases risk of soil erosion.” (see web sites). Farmers should aim to:  “achieve [a] hot [intense?] and even burn to ‘cook’ snails”. “Even though burning is rejected by no-till farmers and farmers on fragile soils with low organic matter, it is one of the most successful methods to reduce high snail numbers in cereal stubble and pastures.” However, conical snails may achieve protection from stubble fires by sliding under rocks. Thus, for these snails, burning “Works best when: [there are] few rocks under which snails can hide”.

Information Sources:

Baker, G.H. (1986). The biology and control of white snails (Mollusca: Helicidae), introduced pests in Australia. CSIRO Division of Entomology Technical Paper 25.

http://www.sardi.sa.gov.au/crops/entomolo/sc_snails.html

http://www.sardi.sa.gov.au/crops/entomolo/snailpest.html

A. Malcolm Gill,
3 rd October, 2002.

[1] I have drawn on the web sites noted. Quotations without explicit reference come from the web pages.