Role of Hormones in Completing the Life History of Insects and Frogs

The role of hormones in completing the life history of insects and frogs involves regulating developmental stages such as metamorphosis, growth, reproduction, and behaviour. The hormones are chemical messengers that play an important role in the life cycle of insects and frogs.

In frogs, the hormone thyroxine is responsible for metamorphosis whereas in insects, ecdysone and juvenile hormones are needed. These hormones are produced in small quantities but are essential for the completion of the life cycle of insects and frogs. In this article, we will study the role of hormones in completing the life cycle of insects and frogs.

What are the Hormones in Insects and Frogs?

Hormones in insects, such as juvenile hormones and ecdysteroids, control growth, metamorphosis, development and behavior. In frogs, thyroid hormones regulate tadpole metamorphosis, while gonadotropin-releasing hormone stimulates reproduction. Corticosteroids in frogs respond to stress and regulate metabolism. Environmental factors like pollutants can disrupt hormonal balance and seasonal variation influences hormone levels and developmental timing. Hormonal feedback mechanisms maintain homeostasis.

Role of Hormone in Insects Metamorphosis

Insects have several hormones that control their growth and development. These hormones regulate a variety of developmental processes, including embryogenesis, larval growth and moulting, metamorphosis, and reproduction. They also control other processes in insects, like metabolism, muscle activity, tanning, and colour change. The two major endocrine hormones that regulate these processes are the steroid hormone ecdysone and juvenile hormone. The role of these hormones are explained below:

Role of Ecdysteroids in Insects

Ecdysteroids are a class of steroid hormones that control molting and metamorphosis in insects. They are also found in crustaceans and spiders. Ecdysteroids are also known as “moulting hormones”. Ecdysteroids are produced in the following ways:

• Larval stages: Synthesized from dietary cholesterol in the prothoracic glands.
• Adult insects: Synthesized by the gonads.

Ecdysteroids are involved in the process of differentiation of tissues and organs during development, regulates reproductive processes, such as ovarian development and egg maturation.

Role of Juvenile Hormone in Insects

Juvenile hormone is a group of sesquiterpenoids that regulate insect development and physiology. JH is produced in the corpus allatum, a paired neuroendocrine gland. It secretes Juveline hormone (JH) into the hemolymph for delivery to target tissues.

• JH affects the process of molting, the periodic shedding of the outer skeleton during development. 
• In adults it is necessary for normal egg production in females.
• Juveline hormone is a regulator of multiple developmental and physiological processes, such as metamorphosis, reproduction, and behavior. It’s known for its ability to delay metamorphosis.

Role of Hormones in Metamorphosis of Frog

Hormonal regulation in frogs is responsible for the changes that occur during metamorphosis. The role of various hormone in growth and development of frog is explained below:

Thyroid Hormones

The thyroid glands of frogs are located between their eyes and undergo various morphological changes during metamorphosis. The thyroid gland secretes thyroxine (T4) and triiodothyronine (T3) hormones during metamorphosis. Thyroxine is produced by the thyroid gland and secreted into the bloodstream. 

• Thyroid hormones help in the differentiation of tissues and organs during metamorphosis. It plays a role in the transition from aquatic tadpole to terrestrial frog.
• Thyroid hormone promote the resorption of the tadpole’s tail, an important step in metamorphosis. It play an important role in the development of hind limbs and transition to a fully functional frog.

Gonadotropin-Releasing Hormone

Gonadotropin-Releasing Hormone is produced in the hypothalamus, and acts on the pituitary gland to release gonadotropins. Gonadotropin-Releasing Hormone in frogs stimulates gonadal development and regulates reproductive behaviors. GnRH secretion is influenced by environmental and seasonal variations, coordinating with reproductive cycles.

Factors Affecting Hormonal Control in Insects and Frogs Metamorphosis

Environmental factors like temperature, light, and nutrition can influence hormone secretion in insects and frogs.

Temperature

Insects: Temperature can affect the rate of hormone synthesis and secretion. Warmer temperatures generally accelerate metabolic processes, including hormone synthesis. It influences various developmental processes such as molting and metamorphosis. It may lead to faster growth and development in insects.

Frogs: Temperature regulates the activity of the hypothalamus and pituitary gland, which control hormone secretion in frogs. Warmer temperatures may lead to faster growth and development in frogs. Variation in temperature can affect the timing and progression of tadpole development and metamorphosis.

Light

Insects: Light influences hormone secretion and influence specific behaviors such as reproduction, migration, and diapause. Photoperiod can regulate the synthesis and release of hormones like juvenile hormones and ecdysone. It control insect growth and development.

Frogs: Light exposure can affect the secretion of hormones such as melatonin and corticosterone in frogs. Photoperiod help regulate seasonal changes in hormone levels. It influences reproductive behaviors and the timing of metamorphosis in tadpoles.

Nutrition

Insects: Availability of nutrition directly impacts hormone synthesis and secretion in insects. Adequate nutrition is essential for the production of hormones like juvenile hormones, which regulate growth and development. Poor nutrition can disrupt hormone balance, leading to developmental abnormalities or delayed metamorphosis.

Frogs: Nutrient availability affects hormone secretion and metabolic processes involved in tadpole growth and tissue differentiation. Nutrition influences the tadpole growth and development. Inadequate nutrition can delay metamorphosis or result in smaller, weaker adult frogs.

Environmental Stress

Both insects and frogs may experience environmental stress such as pollution, habitat loss, and climate change, which can disrupt hormone secretion and affect their life cycle. Stress hormones like cortisol in frogs and catecholamines in insects may increase under adverse environmental conditions. It may alter the developmental processes and reproductive behaviors.

Conclusion – Role of Hormones in the Life History of Insects and Frogs

Hormones plays an important role in regulating and coordinating the life history of insects and frogs. They control growth, development, metamorphosis, behaviour and reproductive processes. It ensures the successful completion of their life cycles that ensures their continuation. In insects, the hormones ecdysone and juvenile hormone help in the transition from pupa to adult form and in frogs, the hormone thyroxine help in the transformation of a tadpole into a frog.

FAQs on Role of Hormones in Completing the Life History of Insects and Frogs

What are the Hormones in Insects Class 8?

Hormones in insects include ecdysone, juvenile hormone, and various neuropeptides, which regulate growth, metamorphosis, reproduction, and other physiological processes essential for insect development and survival.

What is the Role of Hormones in Growth of Insects?

Hormones in insects regulate growth by controlling processes such as molting and tissue development, ensuring proper development from larvae to adults.

Which Hormones are Responsible for the Life Cycle of a Frog?

The life cycle of a frog is governed by hormones such as thyroxine, prolactin, and corticosteroids, which coordinate metamorphosis from tadpole to frog.

How do Hormones Help in the Completion of Life History of Insects and Frogs?

Hormones play a crucial role in the completion of life history in insects and frogs by orchestrating developmental stages like growth, metamorphosis, and reproduction, ensuring successful transition between life stages.

How do Hormones Influence Metamorphosis in Insects and Frogs?

Hormones like ecdysone in insects and thyroxine in frogs trigger and regulate metamorphosis. It help in the transformation from larval to adult forms.

Which of the Following Hormones is Responsible for Metamorphosis in Frogs?

The thyroid gland secretes the hormones thyroxine (T4) and triiodothyronine (T3), which are responsible for the metamorphosis of frogs.

Which Hormone is Responsible for Metamorphosis in Insect?

Ecdysone and juvenile hormones (JHs) are the key hormones that control insect metamorphosis and molting.

What are the Major Hormones in Insects?

The major hormones in insects include ecdysone and juvenile hormone.