Question

The development ofPoriplaneta americana is (a) holometabolous (b) paurometabolous (c) ametabolous (d) hemimetabolous.

Short answer

The development of Poriplaneta americana is (b) paurometabolous.

Step-by-step solution

Understanding the Question

The question asks to identify the type of development that occurs in the species 'Poriplaneta americana' which is commonly known as the American cockroach.

Understanding Types of Insect Development

There are different types of insect development: Holometabolous development involves a complete metamorphosis with distinct egg, larva, pupa, and adult stages. Paurometabolous development involves gradual metamorphosis where the young resemble the adults. Ametabolous development shows no metamorphosis, and the insect looks the same from hatching to adult. Hemimetabolous, or incomplete metamorphosis, involves a nymph stage that gradually resembles the adult.

Identifying the Correct Type of Development for Poriplaneta americana

The American cockroach, Poriplaneta americana, undergoes paurometabolous development, where the immature stages (nymphs) resemble the adults but are smaller and lack wings and reproductive structures. They undergo a series of molts until they reach the adult form.

Key concepts

Insect development types

Insects are incredibly diverse, not just in terms of species, but also in how they grow and develop. To understand the life cycle of any insect, including the American cockroach, it's crucial to become familiar with the following major types of development.

• Holometabolous Development: This is a type of complete metamorphosis seen in many insects, such as butterflies and beetles. It includes four distinct life stages: egg, larva, pupa, and adult. The larval stage looks entirely different from the adult, often feeding on different sources and living in different habitats.
• Paurometabolous Development: Involves gradual metamorphosis where the young, called nymphs, progressively morph into adults. They usually inhabit the same environments and have similar diets as their adult counterparts.
• Ametabolous Development: This type occurs when there's no metamorphosis. Insects that develop ametabolously look largely the same from hatching to adulthood, simply growing larger in size.
• Hemimetabolous Development: Also known as incomplete metamorphosis, here the insect emerges from the egg into a nymph stage which incrementally matures into the adult form.

By comparing these types, we can place the American cockroach into the right category and better understand its growth and life strategies.

Paurometabolous development

Paurometabolous development, also known as gradual metamorphosis, can be thought of as a series of steps rather than a total transformation. The young insects that hatch from eggs are called nymphs, and they resemble miniature adults in many ways but lack fully developed wings and reproductive organs.

• Nymph Stage: During this stage, which includes multiple molts, nymphs grow in size and gradually develop adult features.
• Molting: As the nymph grows, it sheds its exoskeleton in a process called ecdysis. This is necessary because the exoskeleton does not grow once formed.
• Subadult Stage: Eventually, nymphs enter a phase where they closely resemble adults but are not yet capable of reproduction.
• Adult Stage: The final molt reveals the sexually mature adult, with fully developed wings and the ability to reproduce.

The American cockroach undergoes this type of development, which is easier to observe and follow than the dramatic changes witnessed in holometabolous development.

American cockroach life cycle

The American cockroach, 'Periplaneta americana', has a life cycle that is characterized by paurometabolous development. Here's what this looks like for the American cockroach:

• Egg Stage: The female cockroach lays eggs contained within a case called an ootheca.
• Nymph Stage: Once the eggs hatch, nymphs emerge. These nymphs are wingless and lack reproductive structures but already resemble the adults in terms of their behavior and diet.
• Molting: Nymphs will molt several times. With each molt, they grow bigger, and their adult features, such as wings, become more pronounced.
• Adult Stage: After the final molt, the nymph becomes an adult. This stage is marked by the capacity for reproduction and, in the case of males, fully developed wings that allow them to fly. Females also have wings but do not fly as often.

Understanding the life cycle of the American cockroach is not just about memorizing these stages but observing how they interact with the environment at each stage. This knowledge is essential for both pest management strategies and appreciating this often-misunderstood creature.