The proglottid can copulate with itself, with others in the strobilla, or with those in other worms. When the segment reaches the end of its strobila, it disintegrates en route, releasing eggs in a process called apolysis. Lifecycle
H. nana is the only cestode capable of completing its lifecycle without an intermediate host. It can, however, pass through an intermediate host, as well. The most common intermediate hosts for H. nana are arthropods (e.g. flour beetles). When an egg is ingested by the definitive host, it hatches and releases a six-hook larva called the oncosphere (hexacanth) which penetrates the villi of the small intestine and develops into a cysticercoid. Infection
Transmission of H.nana occurs by the fecal-oral route. It also occurs by accidental ingestion of an insect containing the cysticercoid. Screening for activity against H. nana
H. nana in mice is used because:
Human infection is easily maintained in mice. Its armed scolex is similar to other pathogenic tapeworms. It corresponds to other tapeworms in its sensitivity to standard anthelmintics,Method:
Mature worms are collected from infected mice. Terminal gravid proglottids are removed, crushed under coverslips, and eggs are removed. Eggs containing hooklets (mature) are counted. 0.2 ml stock soln. containing 1000 eggs/ml given to each mouse. Adult worms develop in 15–17 days. The test drug is given orally; mice are necropsied on the third day after treatment. A standard drug is given. The intestines are examined under a dissecting microscope for worms or scolices. The response is measured bt the number mice cleared.
Also known as the rat tapeworm, H. diminuta adults live and mate in the bowels of rats. Eggs of H. diminuta are excreted by the rats in droppings, which are frequently consumed by beetles. Once inside the beetle, the eggs mature into a cysticercoid. The juvenile tapeworms claw their way out of the beetle gut into the circulatory system by means of their three pairs of hooks. There, they wait for a rat to ingest the host beetle, where they mature to adult form, lay eggs, and restart the entire cycle. Beetle manipulation
H. diminuta has an effective mechanism for interspecies transfection. Beetles prefer to ingest rat droppings infected with tapeworm eggs, because of their odor. It is not known if the odor is produced specifically by the eggs or the droppings. H. diminuta also sterilizes its beetle host, if female. This is so the beetle does not waste energy in its reproductive system, allowing H. diminuta to further exploit the beetles metabolic resources. H. nana
H. nana is a tapeworm, belonging to the class Cestoidea, phylum Platyhelminthes. It consists of a linear series of sets of reproductive organs of both sexes; each set is referred to as a genitaluim and the area around it is a proglottid. New proglottids are continuously differentiated near the anterior end in a process called strobilation. Each segment moves toward the posterior end as a new one takes its place and, during the process, becomes sexually mature.