Haemaphysalis longicornis on sheep and pastures of farmed deer

Abstract

The cattle tick Haemaphysalis longicornis is widespread in the more temperate areas of New Zealand and causes economic losses in the deer industry. It is also a vector of the protozoa which causes Bovine Theileriosis. In this study a few small researches have been done at the Deer Research Unit of Massey University in Palmerston North, New Zealand.

To find which paddocks contained any ticks at all towels were dragged around the paddocks and ticks counted. This was compared with groups of three sheep that stayed in the paddocks for seven days and were then checked for ticks in wool free areas (armpits, groins and in- and outside of the ears). The sheep were able to catch ticks in all paddocks tested. The towelling method only found ticks in the paddocks that had higher tick burdens. The difference in tick-catching ability between towels and sheep was significant with p<0,01.

To find good circumstances to go out tick catching towelling of the paddocks was done under different weather conditions. Also two different colours towels (a white and a dark blue one) were used to see if ticks have a preference for one colour. Not enough data was collected to be able to conclude anything about preferred weather conditions for ticks to become active, but it was noticed that hardly any ticks were found under rainy or windy conditions. It seemed that ticks have a preference for a dark blue towel compared to a white towel, but this was not significant.

The last research was to see how long the ticks stay on a host. It was noted that the ticks stayed on shorter than was expected after reading literature. It also seemed that the ticks weren’t fully engorged when dropping off, and new ticks were seen after a few days even though the sheep were in a known tick free area. It could be possible that ticks moved to another place to engorge further, but more research is required.