The Hunter Snail

Much of the $10 million the U.S. citrus industry spends annually on pest control goes toward fighting the Helix aspersa, a common orchard variety of snail. The Helix feeds indiscriminately on leaves, twigs and fruit. Up to now, the industry has relied on expensive chemical dusts and sprays; unfortunately, they must be applied almost constantly and they are only moderately effective. Last week Curtis P. Clausen of the University of California's Department of Biological Control announced plans to fight the Helix with one of its own kind: the Gonaxis kibweziensis, commonly known as the cannibal snail.

Combat Record. A native of East Afri ca, the Gonaxis has a distinguished battle record against the giant African snail in the islands of the Pacific. On Agiguan in the Marianas, the Gonaxis destroyed within two years nearly a million of the 5,000,000 African snails whose ancestors were brought in as emergency food by the Japanese during World War II. When Clausen heard that 5,000 Gonaxis snails had been rounded up on Agiguan for anti-pest assignments on other islands, he put in a bid for a consignment of 200. Currently being fed on a diet of Helix snails in the university laboratories, they will be turned loose in the spring in selected orange and lemon groves from Santa Barbara to San Diego.

The Gonaxis, less than an inch long, attacks by attaching itself to the foot of the garden snail and devouring it alive with minute, filelike teeth as it retreats into its shell. Although the Gonaxis occasionally turns on one of its own kind (chiefly baby snails), it generally attacks only a snail of a different species. In its native Africa, the Gonaxis has maintained a healthy balance in the snail population.

Natural Balance. Similarly, the Helix snail, presumably imported from Europe, did not become a hazard to citrus groves until it reached California. In effect, what the biologists hope to do is restore a natural balance, which was upset when the Helix left home.

Not everyone is glad to see the Gonaxis arrive in California. The state has its own carnivorous snails, and for years they have been doing a good job of keeping native California snails in check. Why import a foreign variety? In reply, Clausen points to the fact that California snails have generally stuck to wild areas, and presumably could not be coaxed into orchards. More over, says Clausen, he does not fear that the Gonaxis will devour the Helix and turn to other food. Long before that happens, the law of supply and demand will take over, freezing the population of both hunter and hunted at a safe level.

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