Rondelaud D
Ann Parasitol Hum Comp. 1981;56(1):45-56. doi: 10.1051/parasite/1981561045.
The author analyzes the positive and negative results of a year of biological control by predation on 49 stations of Lymnaea truncatula in Haute-Vienne, France. The negative results can be explained by the effects of 6 natural factors: 1--the rainfall over the habitats during the first 10 days of the experimentation. The rate of natural mortality and predation of L. truncatula is reduced at values above 8 mm rainfall. The predatory snails leave the sodden soil and do not consume L. truncatula; 2--the presence of stone blocks on the habitat. These blocks constitute shelters for L. truncatula; 3--the quality of the plant cover. Rushes and graminaceae preferentially must be used; 4--the previous treatment of the habitat by a molluscicide (copper sulphate) just before the application of biological control. The predators preferentially consume the more poisoned L. truncatula and forsake the more healthy snails; 5--the presence of phoretic acaridae on the predators which die; 6--the behaviour of sheep on the habitats situated on pastures with steep slopes. Their repeated passages cause the squashing of the predators. The proposed solutions are discussed in the limits of the region of experimentation.
作者分析了在法国上维埃纳省对49个截口圆扁螺监测点进行为期一年的捕食性生物防治的正负结果。负面结果可由6种自然因素的影响来解释：1——实验开始前十天栖息地的降雨量。降雨量超过8毫米时，截口圆扁螺的自然死亡率和被捕食率会降低。捕食性蜗牛会离开湿透的土壤，不再捕食截口圆扁螺；2——栖息地存在石块。这些石块为截口圆扁螺提供了庇护所；3——植被覆盖的质量。优先选用灯心草和禾本科植物；4——在进行生物防治前，栖息地刚用过杀螺剂（硫酸铜）。捕食者优先捕食中毒更深的截口圆扁螺，而舍弃更健康的蜗牛；5——死亡的捕食者身上有携播螨科螨虫；6——在陡坡牧场的栖息地中羊的行为。它们反复经过会压死捕食者。在实验区域范围内对提出的解决方案进行了讨论。
