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In Cockroach, nymphal characters are maintained by,
(This question has multiple correct options)
A. Ecdysone
B. Salivary glands
C. Parotid gland
D. Juvenile hormone

Last updated date: 20th Jun 2024
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Hint: Cockroaches are a group of omnivorous and cursorial (running by legs) insects, nocturnal (more active at night), included in the Class-Insect of Phylum Arthropoda of Kingdom Animalia. They are found to be in places where dampness, warmth and plenty of organic food is found.

Complete step-by-step answer:
The female cockroach contains the ootheca, protruding from the tip of her abdomen for many days, till the time it gets deposited to a suitable surface, commonly in a crack or services where high relative humidity is present like near a food resource.
Every egg inside the ootheca undergoes the process of cleavage and finally results in the nymph’s formation. Freshly hatched nymphs are delicate, transparent and almost colourless having black eyes. They contain nearly all adult characters but variates in size and colour, in being sexually immature and lack of wings. The next to the last nymphal stage contains wing pads but only the adult cockroaches contain wings.
The nymph develops and grows by the process of moulting about 13 times to attain the adult form. This development consists of the formation of wings, growth of body size, change in colour (colour changes to dark brown or black) and development of genitalia, etc. The development of cockroach, called Periplaneta Americana is through gradual metamorphosis, means occurs through a series of nymphal stages and hence is called as "paurometabolous".
Now let’s talk about the information about given option:
> Ecdysone: Ecdysone is secreted by Prothoracic gland to control ecdysis of the nymph. These glands degenerate after the process of metamorphosis.
> Salivary glands: These glands are found in humans and absent in insects. They are used to produce saliva. They help in thoroughly mixing food.
> Parotid gland: This gland is found in humans near the cheek area. It is a type of salivary gland. It doesn’t perform any role in metamorphosis.
> Juvenile hormone: Corpora Allata secrete a juvenile hormone namely ‘Neotinin’, which retains nymphal characters which keeps a check on the appearance of adult characters. When juvenile hormone is absent, it allows the appearance of the adult characters. In adult cockroaches, a gonadotropic hormone is secreted by Corpora allata which regulates the development and functioning of reproductive organs.

Hence, the correct answers are option (A) and (D). Ecdysone and Juvenile hormone.

Note: Metamorphosis is reported in insects which is thus regulated by two hormones, ecdysone which is secreted by prothoracic glands and juvenile hormone which is secreted by corpora allata. Neurosecretory cells are associated with the brain and secrete brain hormone which in turn activates the prothoracic glands to secrete their hormone.