Fourie L J, Kok D J, Krugel L, Snyman A, Van Der Lingen F
Department of Zoology and Entomology, University of the Orange Free State, Bloemfontein, South Africa.
Med Vet Entomol. 1996 Jan;10(1):39-43. doi: 10.1111/j.1365-2915.1996.tb00080.x.
Karoo paralysis, caused by feeding Ixodes rubicundus females, is a major disease of small stock in South Africa. Control methods currently practised are almost exclusively chemical based. To limit overdependance on chemicals, vegetation management was investigated as a possible method for control, to be incorporated in an integrated tick management system. Laboratory and field experiments were conducted to determine, firstly, the extent of vertical migration and survival of ticks on long and short copper rods which simulated grasses as questing substrates; secondly, the infestation burdens of sheep exposed to similar tick challenges in pens with long and short grass; and thirdly, the effect of trimming the lower crown line of wild olive trees, simulating the browsing effect of goats, on tick density in the immediate environment of the trees. When ticks were exposed to optimal ( > 45 cm) and sub-optimal ( < 10 cm) length rods on which to quest, the extent of vertical migration over extended periods of time (up to 87 days) was significantly higher (P < 0.001) for the ticks exposed to long rods. Also, almost 3 times as many ticks exposed to long rods survived compared to those exposed to short rods. Sheep exposed to long grass were infested by twice as many ticks compared to those exposed to short grass. Tick density at modified wild olive trees (Olea europaea africana) (0.027 ticks/m2) differed significantly (P < 0.05) from that at control trees (0.088 ticks/m2). It is recommended that coarse grazers such as cattle and horses should be used to graze down long grasses before sheep are introduced into camps known to be infested with I. rubicundus. Similarly, domestic goats can, through their browsing effect on shrubs and trees, modify the vegetation and as such play an important role in an integrated tick management system.
由血红扇头蜱雌蜱叮咬引起的卡鲁麻痹是南非小家畜的一种主要疾病。目前采用的控制方法几乎完全基于化学手段。为了减少对化学药品的过度依赖，人们研究了植被管理作为一种可能的控制方法，以便纳入综合蜱虫管理系统。开展了实验室和野外实验，首先是确定蜱虫在模拟草丛作为宿主寻找基质的长、短铜棒上的垂直迁移程度和存活情况；其次是确定在长草和短草围栏中面临类似蜱虫挑战的绵羊的感染负担；第三是确定修剪野生橄榄树下部树冠线（模拟山羊的啃食效果）对树木周围环境中蜱虫密度的影响。当蜱虫接触到适合（> 45厘米）和不适合（< 10厘米）长度的宿主寻找棒时，在较长时间（长达87天）内，接触长棒的蜱虫垂直迁移程度显著更高（P < 0.001）。此外，接触长棒的蜱虫存活数量几乎是接触短棒蜱虫的3倍。接触长草的绵羊感染的蜱虫数量是接触短草绵羊的两倍。经过改造的野生橄榄树（非洲油橄榄）处的蜱虫密度（0.027只蜱虫/平方米）与对照树处（0.088只蜱虫/平方米）有显著差异（P < 0.05）。建议在将绵羊引入已知感染血红扇头蜱的营地之前，先用牛和马等粗食草动物啃食长草。同样，家山羊通过对灌木和树木的啃食作用，可以改变植被，因此在综合蜱虫管理系统中发挥重要作用。
