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Natural Compound May Curb Losses Caused by Snails
By Luis Pons
July 25, 2003
A compound found in a variant of the weed mugwort may help Asian rice growers and U.S. catfish farmers stem snail-related losses.
Agricultural Research Service studies have found that a natural compound, Vulgarone B, is a potent and relatively inexpensive control agent against golden apple and ram's horn snails.
The research, led by chemist Kumudini Meepagala at the ARS Natural Products Utilization Research Laboratory in Oxford, Miss., showed that Vulgarone B is just as effective as--and faster acting than--"Meta," a commercial product currently used against golden apple snails.
The research on golden apple snails, Pomacea canaliculata, was done in collaboration with the Philippines Rice Research Institute, based in Nueva Ecija. These snails devastate rice fields by feeding on the base of paddy seedlings, as well as on plant leaves and stems.
Since being introduced to Taiwan from the Americas during the 1980s, golden apple snails have caused about $1 billion in crop losses in Indonesia, Thailand, Cambodia, Hong Kong, southern China, Japan and the Philippines.
The ram's horn snail, Planorbella trivolvis, is an intermediate host for Bolbophorus confusus, a parasitic flatworm that over the past four years has cost commercial catfish farmers in Mississippi, Arkansas, Louisiana, Alabama and California millions of dollars in losses. The parasite kills smaller fish and reduces the growth of those that survive infection.
According to Meepagala, Vulgarone B--which can be sprayed, placed in attractant traps or put directly into pond or rice paddy water--is nontoxic to grass, lettuce and rice plants. It hasn't been tested yet on mammals.
The compound is found in the oil of a variety of Artemisia douglasiana, an easily grown member of the sunflower family. It can be enriched by steam distillation, a simple and low-cost process. Meepagala got this plant from horticulturalist George Sturtz of AromaGen, an Oregon-based botanical firm.
Vulgarone B has previously shown antifungal activity against plant pathogenic fungi that cause anthracnose disease in strawberry plants.
ARS is the U.S. Department of Agriculture's chief scientific research agency.