Volume 22, Issue 2
  • ISSN: 0002-9637
  • E-ISSN: 1476-1645


A biological control method is reported, utilizing an ampullarid snail, to eliminate the molluscan host of The limitations and economics of this method required further clarification. This study was conducted in nine small reservoirs in Puerto Rico to establish the probability of success of the method under various loading rates and vegetation conditions. Adult were transplanted from natural habitats into 7 of 9 study ponds, all of which contained stable populations of the planorbid snails. The snail populations were monitored for almost 2 years after the initial loading with Although the planorbid snail populations remained strong in the untreated ponds, they were controlled in two of the treated ponds, and significantly reduced in three others. In the remaining two treated ponds there was no significant decrease in the populations. There was a close correlation between the success of the method and the amount of vegetation in the ponds. In the two ponds where the planorbid snails were controlled, there was very little vegetation. In the two ponds where the planorbids were not affected, the surfaces of the ponds were completely covered with vegetation. There was no correlation between the success of the biological control method and the rate at which the were added to the ponds. The average loading rate for all seven ponds was two per m of pond surface.


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