Insects

__Insects and the Story behind Them __

__By: Christina Katbe, Juliette Jabra, Maria Murr, Peter Kay, and Karl Bouchikian __

__Body Characteristics __

Insects have __segmented__ bodies that are supported by an exoskeleton that is made mostly of __chitin__. The segments of the body are divided into three groups, the head, the thorax, and the abdomen. An insect’s head has a pair of antennae, eyes, and a mouth. The antennae are used to touch and smell. The eyes are simple or compound. Simple eyes detect light and darkness. Compound eyes contain many lenses and can detect colors and movement. When insects have three pairs of legs and one or two pairs of wings, they are attached to the thorax. Some insects do not have wings and other insects have wings only for part of their lives. Insects are the only vertebrates that can fly. Flying allows insects to find habitat, food, and mates. Flight also helps them escape from predators. In vertebrates such as insects, the abdomen is a large cavity closed by the abdominal muscles and the vertebral column. The abdomen has neither wings nor legs but it is where the reproductive systems are found. Most adult insects have two pairs of wings, but some have only one pair. Usually insect wings are __membranous__ but in some insects they can be rough and hard. Sometimes, the wings bear hairs or small scales. Adult insects have 6 legs. Each segments of the thorax bears one pair of legs. The legs are segmented. Often the last segment of the leg has a small claw. For some insects, the legs are especially adapted for jumping.
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__Definitions: __ · Segmented: One of the parts into which something naturally separates or is divided. · <span style="font-family: 'Verdana','sans-serif'; font-size: 12pt; line-height: 115%;">Chitin: Nitrogen that forms a transparent substance and is a part of the exoskeleton or outer covering of insects. · <span style="font-family: 'Verdana','sans-serif'; font-size: 12pt; line-height: 115%;">Membranous: Consisting of a membrane.





<span style="font-family: Verdana,Geneva,sans-serif; font-size: 16pt;">Habitat of insects

<span style="font-family: Verdana,Geneva,sans-serif; font-size: 13pt;">Insects live in places all over the world however most insects are located in humid countries that have hot whether. Insects could be found in many different places like houses, beaches and on plants. <span style="font-family: Verdana,Geneva,sans-serif; font-size: 13pt;">Body systems( growth and Reproduction- Respiratory system- Fat body-CNS-Circulation- digestive System) **
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​ __<span style="font-family: Verdana,Geneva,sans-serif; font-size: 13pt; line-height: 115%;">Growth and Reproduction __

<span style="font-family: Verdana,Geneva,sans-serif; font-size: 13pt;">The reproductive activity of the male insect is little affected by nutrition but all kinds of nutritional factors may influence the production of eggs in the female. The sexes are separate in an insect which means they are not hermaphrodite. Their reproduction is usually sexual in which he male sperm fertilizes the female's egg and impregnates the female. However, in many insect groups the eggs develop without fertilization by sperm. This process is called parthenogenesis. Parthenogenesis is the process in which an unfertilized egg develops into a new individual and it is common in insects. In some insects such as bees unfertilized eggs become males and fertilized eggs become females. In other species such as aphids all the female generations are produced by parthenogenesis. What basically happens is eggs are usually laid in a sheltered place and they are kept there and hatch inside the egg. After hatching, the insect must shed off its skin as it grows, since the firm exoskeleton or protective outside skeleton does not allow the insect to grow very much, a new soft exoskeleton forms beneath the old exoskeleton and after each shedding the insect undergoes a quick growth before its new covering hardens. The stages between molts (shedding) are called instars; the final instar is the adult.

__<span style="font-family: 'Verdana','sans-serif'; font-size: 18pt; line-height: 115%;">Respiratory System __ <span style="font-family: 'Verdana','sans-serif'; font-size: 13pt; line-height: 115%;">The respiratory system carries oxygen to the cells. Spiracles which are openings in the body wall are attached to a network of silvery white tubes called trachea. Air enters the spiracles and trachea carries oxygen to the insect’s cells. Blood does not carry the oxygen to the insects, only the trachea tubes carry oxygen. __<span style="font-family: Verdana,Geneva,sans-serif; font-size: 15pt; line-height: 115%;"> <span style="font-family: Verdana,Geneva,sans-serif; font-size: 16pt;">Fat Body __ <span style="font-family: Verdana,Geneva,sans-serif; font-size: 13pt; line-height: 115%;">The major tissue for metabolism and storage of nutrients is the fat body. The metabolism is the set of chemical reactions that happen in living organisms to maintain life. Most of the fat body is in the abdomen which surrounds the guts. Over there it can quickly take up absorbed nutrients. Some fat body is scattered throughout the body near the tissue the uses its nutrients. The metabolic function of the fat body is it stores extra nutrients and it combines proteins, lipids, and carbohydrates that circulate in the insect’s blood. __<span style="font-family: Verdana,Geneva,sans-serif; font-size: 16pt; line-height: 115%;">CNS (Central Nervous System) __ <span style="font-family: 'Verdana','sans-serif'; font-size: 13pt; line-height: 115%;">The nervous system passes information about internal and external environments and shows the behavior of the insect. The insect’s central nervous system is made up of the brain and the ventral nerve cord. The ventral nerve cord is a structure that makes up the nervous system of insects. The brain is made up of dumb bell shaped visual lobes with nerves that develop on the outside of the compound eyes. The ventral nerve cord is made up of a series of ganglia, usually one per segment. The ganglia are thickened parts of the nervous system and they contain the cell bodies of nerve cells. Ganglia are connected by paired nerves called interganglionic connective __<span style="font-family: Verdana,Geneva,sans-serif; font-size: 16pt; line-height: 115%;">Circulation __ <span style="font-family: 'Verdana','sans-serif'; font-size: 13pt; line-height: 115%;">The circulatory system sends important metabolites from the fat body to the cells, carries wastes to the excretion part of the insect’s body and it gives immunity to harmful organisms. A metabolite is any substance that takes part in chemical reaction throughout the body. Insects have a simple open circulatory system. The circulatory system is made up of vessels running through the length of the body. These vessels are divided into a later heart that contains structures into a later heart that contains structures in the hollow of the heart. __<span style="font-family: Verdana,Geneva,sans-serif; font-size: 16pt; line-height: 115%;">Digestive System __ <span style="font-family: 'Verdana','sans-serif'; font-size: 13pt;">Insect digestive systems are used to digest a variety of food, but they have common structures. The digestive system is divided into three main sections. The foregut makes and stirs food before digestion. Food moves from the foregut to the midgut where it is digested and the nutrients are absorbed in the body. Malpighian tubules are also used in the digestion process. They are the organs in which insects excrete wastes. Undigested foods from the midgut and Malpighian tubules pass through the hindgut. There, the hindgut absorbs useful products and the rest of the undigested food is excreted.

__<span style="font-family: 'Verdana','sans-serif'; font-size: 18pt; line-height: 115%;"> Beneficial Insects and their Disadvantages __ <span style="font-family: 'Verdana','sans-serif'; font-size: 12pt; line-height: 115%;">Many insects are valuable as predators to harmful species and some are important as scavengers and as aerators of the soil. Aerators are insects that mix soil and air. Another important function for insects is that many plants depend on them as agents of pollination meaning they exert a force or effect that helps the pollination process. Insects are also the source of products such as honey, beeswax, and silk. Insects are also a major source of food for many animals and the fruit fly has been the experimental animal used in genetics. Some insect pests cause enormous damage to crops by eating the plants.

__<span style="font-family: 'Verdana','sans-serif'; font-size: 18pt; line-height: 115%;">Feeding Habits __

​ <span style="font-family: Verdana,Geneva,sans-serif; font-size: 13pt;">When it comes to food, insects eat anything they see, like dirt, plants, leaves, fruit etc. Most insects are plant eaters. Others feed on each other. Some have very specialized eating habits. Praying mantises have very large front legs for capturing other insects. They have a jaw like mandible to chew the exoskeleton of the insect prey. Female mosquitoes have straw like mouths with a sucking tube to get out blood and other liquids out of an animal. Some insects prefer eating fruit which are known as fruit flies, while others like eating leaves which are called caterpillars. Almost half are plant eaters, feeding on leaves, roots, seeds, nectar, or wood. Fleas and lice are types of insects which are parasites, which are small insects that suck the blood of larger animals without killing them.

<span style="color: black; font-family: 'Verdana','sans-serif'; font-size: 10pt;">__<span style="font-family: Verdana,Geneva,sans-serif; font-size: 16pt;">Insect Metamorphosis __ <span style="color: #000000; font-family: Verdana,Geneva,sans-serif; font-size: 13pt; line-height: 150%;">Metamorphosis refers to the way that insects develop, grow, and change form. There are two types of metamorphosis incomplete and complete. About 12% of all insects undergo incomplete metamorphosis. Incomplete metamorphosis has three stages. The first stage is the egg. A female insect lays eggs. These eggs are usually covered by an egg case which protects the eggs and holds them together. The second stage of metamorphosis is he nymph. The eggs hatch into nymphs. Nymphs don’t have wings. Nymphs shed their exoskeleton 4-8 times. The third stage of incomplete metamorphosis is the adult. In the adult stage insects stop molting and they grow wings. About 88% of all insects go through complete metamorphosis. Complete metamorphosis has four stages. The first stage is the egg. A female insect also lays eggs. The second stage is the larva. Larva hatches from the eggs. They do not look like adults. They usually have a worm-like shape. Larva molt their skin several times and they grow slightly larger. The third stage of reproduction is the pupa. In this stage larva make cocoons around themselves. Larvae don’t eat while they are inside their cocoons. Their bodies develop into an adult shape with wings, legs, internal organs, etc. This change takes from 4 days to several months. The last stage of complete metamorphosis is the adult. Inside the cocoon, the larvae change into adults. After a period of time, the adult breaks out of the cocoon.


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<span style="font-family: Verdana,Geneva,sans-serif; font-size: 16pt;">**__Question 1: Social insects__** <span style="font-family: Verdana,Geneva,sans-serif; font-size: 13pt;">Social insects are insects that live in colonies and have three characteristics, which are group integration, division of labor, and overlap of generations. Group integration is when a group of insects are united; division of labor is when a group of insects divide their duties equally among each other. Termites and ants and various bees and wasps are the best examples of social insects. Social insects are different in structure, function, and behavior and they have castes which means that <span style="font-family: Verdana,Geneva,sans-serif; font-size: 13pt;"><span style="color: black; font-family: 'Verdana','sans-serif';">each social insect is specialized to perform certain functions in the colony. The most important insects in a colony are the reproductives. A reproduvtive is the only fertile insect in a colony. An example of a reproductive is a queen which is the only fertile female in a colony of social insects. In a colony of social insects a steriles are also found. Steriles are an infertile couple. <span style="font-family: 'Verdana','sans-serif';">that the <span style="color: black; font-family: 'Verdana','sans-serif';">physically distinct group of individuals.


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<span style="font-family: Verdana,Geneva,sans-serif; font-size: 16pt;"> __**Question two: The bee society**__

<span style="font-family: Verdana,Geneva,sans-serif; font-size: 13pt;">An insect society is a colony of insects working together. Some bees belong to the order Hymenoptera. Most Hymenoptera have two pairs of clear wings and they have chewing mouth parts. Some bees can suck up liquids and they can undergo complete metamorphosis. Bees collect pollen and nectar. They are covered with hairs that trap pollen. They do this while visiting flowers. When a bee is in a flower it gathers pollen and stores the pollen in pollen baskets on its hind legs. A tongue-like part of the bee’s mouth sucks up nectar. Honeybees are social insects. Each member has a specific job to do and honeybees live in colonies. A single honeybee cannot survive by itself; there are three different kinds of honeybees in a colony, the queen, worker, and drone. The queen is the longest bee in the hive but it has short wings. Her most important job is to lay eggs. She is the reproductive and mother of all eggs in the hive. She can lay more than 1,500 eggs a day. A good queen lays one egg in every cell. A drone is a male bee in a colony. Drones are not as large as queens. A drone has large eyes that touch each other at the top of their head. Drones do not have stingers or pollen baskets and their mouth parts are too short to gather nectar. Their only function is to fertilize with the queen and they die in the process of reproduction. While queens and workers develop from fertilized eggs, drone eggs are large. Small drones are developed in worker cells. Workers are smaller than drones and queens but there are lots of them. A strong bee colony can have 100000 workers. These bees keep the colony going. A worker’s job changes with its age. At each age the worker has a specific job to do. For example old workers gather nectar pollen and water. A bee colony is very interesting. All the bees in the colony fight as one. When one part of the colony is threatened, the whole colony reacts. Also, when one bee in the colony is diseased, the colony heals itself or splits into two or more separate colonies. The colony also changes to survive different seasons. For example, when the weather is hot the bees store the heat for the winter.



<span style="font-family: Verdana,Geneva,sans-serif; font-size: 13pt;">Body characteristics: Juliette Jabra Feeding Habits: Maria Murr Body systems: Christina Katbe Beneficial insects and their disadvantage: Peter Kay Social insects: Christina Katbe Bee Society: Christina Katbe and Juliette Jabra Habitat: Christina Katbe Pictures: Christina Katbe and Juliette Jabra __<span style="font-family: 'Verdana','sans-serif'; font-size: 18pt; line-height: 115%;">References: __ __ · <span style="font-family: 'Verdana','sans-serif'; font-size: 12pt; line-height: 115%;">www.wikipedia.org/insects.bodycharacteristics · <span style="font-family: 'Verdana','sans-serif'; font-size: 12pt; line-height: 115%;">www.worldnetweb.princeton.edu/perl/webwn · <span style="font-family: 'Verdana','sans-serif'; font-size: 12pt; line-height: 115%;">www.infoplease.com/c36/sci/AO858839.html · <span style="font-family: 'Verdana','sans-serif'; font-size: 12pt; line-height: 115%;">www.en.wiktionary.org/wiki/aerator · <span style="font-family: 'Verdana','sans-serif'; font-size: 12pt; line-height: 115%;">www.google.com/theimportanceofinsects <span style="font-family: Verdana,Geneva,sans-serif; font-size: 13pt;"> · Animal Diversity Book · <span style="font-family: 'Verdana','sans-serif'; font-size: 12pt; line-height: 115%;">www.wikianswers.com · <span style="font-family: 'Verdana','sans-serif'; font-size: 12pt; line-height: 115%;">www.globio.org · ____<span style="font-family: Verdana,Geneva,sans-serif; font-size: 13pt;">www.kwic.com/species/insects/pics/bugprts2.jpg ·www.cartage.org.lb/en/themes/sciences/zoology/insects/insectanatomy/introduction/insecta · <span style="font-family: 'Verdana','sans-serif'; font-size: 12pt; line-height: 115%;">www.dpughphoto.com/images/wheel%20bug%nymph%20.jpg __ __<span style="font-family: Verdana,Geneva,sans-serif; font-size: 13pt;"> · <span style="color: #4f81bd; font-family: 'Verdana','sans-serif';">[] · <span style="color: #4f81bd; font-family: 'Verdana','sans-serif';">[] · <span style="color: #4f81bd; font-family: 'Verdana','sans-serif';">[] · <span style="color: #4f81bd; font-family: 'Verdana','sans-serif';">http://www.xylemsci.ca/images/thoughts/ladybug_bugs_insects_aphids_beneficial_plants_peppers_.jp · <span style="color: #4f81bd; font-family: 'Verdana','sans-serif';">[|www.atpm.com/6.08/insects/images/insects08.jpg] · <span style="color: #4f81bd; font-family: 'Verdana','sans-serif'; font-style: normal;">[|www.uky.edu/Ag/Entomology/.../4h/**bee**keep/**bee**bio&s.htm] · <span style="color: #4f81bd; font-family: 'Verdana','sans-serif';">[] · [] __