Question

The parasite found in the seminal vesicle of earthworm are:
A. Monocystis
B. Nosema
C. Sarcocystitis
D. Nyctotherus

Answer 1

Hint: These parasites infect only earthworms. The adult form of this parasite is known as the trophozoite

Complete answer: Earthworms are infected by a number of protozoans and other nematode parasites. The earthworms act as intermediate hosts of many parasites of many birds and mammals
The two common parasites/ diseases that infect/ affect earthworms are Monocystis and Rhabditis which infect earthworms alone.
Monocystis is the most common genus of protozoans to infect earthworms.
The growing/ adult form known as the trophozoite and the reproductive forms of these parasites occur in the seminal vesicles of the earthworms.
Monocystis lives as an intracellular parasite in its young and immature stage when it lives in the bundles of the developing sperms. It becomes extracellular in its mature stage.

So, the correct answer is “Option A”.

Additional Information: Nosema apis is a microsporidian (spore-forming, unicellular bacteria). It is a small and unicellular parasite that was recently reclassified as a fungus that mainly affects honey bees. It causes nosemosis.
It is the most common and widespread disease of adult honey bees.
Sarcocystis is a genus of parasites of which the majority of species infect mammals.
Some also infect reptiles and birds. The lifecycle of a typical member of the genus Sarcocystis involves two host species, a definitive host and an intermediate host.

Note:The definitive host refers to the organism in which the parasite reaches its mature and reproductive form. Thus, the parasite is capable of reproduction and propagation at this stage.
For example, human tapeworm makes use of humans as its definitive host.
The host harboring a parasite till it reaches its reproductive stage is known as the intermediate host.
An intermediate host often acts as a vector of the parasite to reach its definitive host.