Grønvold J, Høgh-Schmidt K
Royal Veterinary and Agricultural University, Institute of Hygiene and Microbiology, Frederiksberg, Denmark.
Vet Parasitol. 1989 Apr;31(1):57-70. doi: 10.1016/0304-4017(89)90008-3.
Laboratory experiments were conducted to investigate rain splash dispersal of infective Ostertagia ostertagi larvae (L3) from cow pats to the surroundings during simulated rainfall. Simulated rainfall on dry cow pats resulted in dispersal of only very few L3. When cow pats were watered prior to the experiments, many infective larvae were stimulated to migrate up onto the surface of the pats, where they might be hit by water drops. When pre-watered pats were hit by falling drops, a considerable proportion of L3 was translocated. More than 90% of the translocated larvae were transported passively by splash droplets and only a minor part of the larvae migrated actively in water films or were transported passively by water run-off to the soil surrounding the pats. A reduction of the fall height of the simulated raindrops resulted in a significant reduction of the number of translocated L3. When cow pats were hit by drops of diameters between 2 and 5 mm, it was found that small raindrops were just as effective as large drops in splash dispersal of L3, provided the amount of rain was the same; but individual small drops were less effective in this respect than individual large drops. When splash droplets could travel freely, most of the splash-dispersed L3 were found within a horizontal distance of 90 cm from the pats; this applied for all sizes of drops. Most splash droplets carrying L3 were travelling within a vertical distance of 30 cm from the ground.
开展了实验室实验，以研究在模拟降雨期间，感染性奥斯特他线虫幼虫（L3）从牛粪溅散到周围环境中的情况。对干燥牛粪进行模拟降雨，结果只有极少数L3被溅散。在实验前给牛粪浇水时，许多感染性幼虫被刺激迁移到牛粪表面，在那里它们可能会被水滴击中。当预先浇水的牛粪被下落的水滴击中时，相当一部分L3发生了转移。超过90%的转移幼虫是由溅起的水滴被动运输的，只有一小部分幼虫在水膜中主动迁移或被径流被动运输到牛粪周围的土壤中。模拟雨滴下落高度的降低导致转移的L3数量显著减少。当牛粪被直径在2至5毫米之间的水滴击中时，发现如果雨量相同，小雨滴在L3的溅散方面与大雨滴同样有效；但在这方面，单个小雨滴比单个大雨滴效果要差。当溅起的水滴能够自由移动时，大多数溅散的L3在距离牛粪90厘米的水平距离内被发现；这适用于所有大小的水滴。大多数携带L3的溅起水滴在距离地面30厘米的垂直距离内移动。
