1 Fig. 1.1 shows the life cycle of a three-host tick that affects cattle. Fig. 1.1 (a) Name the stages of the tick labelled X, Y and Z in Fig. 1.1. [3] (b) ...

Labelled answer diagram:

(a) The stages of the tick life cycle:

A three-host tick completes its life cycle by feeding on three separate host animals. After hatching from an egg, the six-legged larva (X) attaches to and feeds on the first host, then drops off to moult on the ground. It develops into an eight-legged nymph (Y), which climbs onto a second host to feed, then drops off again to moult into the adult (Z). The adult attaches to a third host, feeds, and the female lays eggs on the ground to restart the cycle.

(b) How dipping cattle in acaricide solution controls tick infestations:

1. The acaricide kills ticks that are attached to the animal at all developmental stages (larvae, nymphs, and adults), directly reducing the parasite load on the herd. [1]
2. Regular dipping at appropriate intervals breaks the tick's life cycle by killing ticks before they can feed, drop off the host, moult, and re-infest. [1] Since each stage must feed on a host to progress to the next, killing them on the host prevents the next generation from developing.

(c) Two diseases that ticks can transmit to cattle:

1. East Coast fever (caused by the protozoan Theileria parva, transmitted by the brown ear tick). [1]
2. Babesiosis (redwater fever, caused by Babesia species, transmitted by Boophilus ticks). [1]

Other acceptable answers include anaplasmosis (gallsickness) and heartwater.