Final answer:
The intermediate hosts of Dicrocoelium dendriticum, or lancet liver fluke, are snails and ants. The snail serves as the initial intermediate host for the larvae, and the ants serve as the second intermediate host where the larvae induce behavioral changes to ensure transmission to the definitive host.
Step-by-step explanation:
The Dicrocoelium dendriticum, known as the lancet liver fluke, is a type of parasite. This parasite has a complex life cycle involving three hosts. The primary definitive host is usually an herbivore such as a cow or sheep, but the intermediate hosts are of more interest here. Firstly, a snail serves as the initial intermediate host, in which larvae grow and develop. The snail, in response to the irritation caused by the larvae, creates cysts and expels them into the environment.
These cysts are ingested by ants, which act as the second intermediate host. Within the ant, the parasite larvae migrate to and manipulate the insect's brain, causing it to climb to the top of a blade of grass during the night or in early morning, making it more likely to be consumed by the fluke's final, or definitive host like a sheep or cow, and allowing the life cycle of the fluke to continue.
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