Classification of Insect

Entomology

1. Kingdom of Saudi Arabia Al Imam Mohammad Ibn Saud Islamic University College of Science Department of Biology Entomology 353 Bio T. Amani Alsharidah 1441 – 2019

2. Lecture 2 The diversity and Importance of Insect Classification of Insect Study of Metamorphosis Process

3. Entomology Entomology is the study of insects. Entomologists, the people who study insects, observe, collect, rear, and experiment with insects. Research undertaken by entomologists covers the total range of biological disciplines, including evolution, ecology, behavior, anatomy, physiology, biochemistry, and genetics.

4. Why the Biologist work with the Insect ? Ease of culturing in a laboratory. Rapid population turnover. Availability of many individuals are important factors. The minimal ethical concerns regarding responsible experimental use of insects, as compared with vertebrates.

5. The Diversity Of Insects Feeding specializations of different insect groups include ingestion of detritus, rotting materials, living and deadwood, and fungus. predation and parasitism. The diversity of insect life style, Its may live in water, on land, or in soil, during part or all of their lives. Insect life cycles allow survival under a wide range of conditions.

6. The Importance of Insect Insects are essential to the following ecosystem functions: nutrient recycling, via leaflitter and wood degradation, dispersal of fungi, disposal of carrion and dung, and soil turnover. plant propagation, including pollination and seed dispersal maintenance of plant community composition and structure, via phytophagy, including seed feeding. food for insectivorous vertebrates, such as many birds, mammals, reptiles, and fish. maintenance of animal community structure, through transmission of diseases of large animals, and predation and parasitism of smaller ones.

7. The Importance of Insect Insects contain a vast array of chemical compounds, such as Chitin, a component of insect cuticle, and its derivatives act as anticoagulants, enhance wound and burn healing, reduce serum cholesterol, serve as non-allergenic drug carriers, provide strong biodegradable plastics, and enhance removal of pollutants from waste water. Drosophila melanogaster, have made it a model research organism. Studies of D. melanogaster have provided the foundations for our understanding of genetics and cytology, and these flies continue to provide the experimental materials for advances in molecular biology.

8. Classification of Insect The formal naming of insects follows the rules of nomenclature developed for all animals. The Linnaean system, which provides every described species with two given names (a binomen). The first is the generic (genus) name, used for a usually broader grouping than the second name, which is the specific (species) name. Kingdom > Phylum > Class > Order > Family > Genus > Species Kingdom=Animal Phylum=Arthropods Class= Insecta Order = Depending on the classification system used, some 25 to 30 orders of Insecta may be recognized.

9. Classification of Insect Divided into these orders based on structure of wings and mouthparts and their type of metamorphosis.

10. Activates 4 Grade. Choose one order, and make presentation about it ( no more than 5 Slide). Presented for your classmate.

11. General Characteristic of Arthropod Arthropoda ( Arthon - Jointed; podos- legs). Arthropoda, animals having jointed appendages or legs (which are modified to different structures to perform different functions like jaws, gills, walking legs, paddle). Most successful phylum on the Earth. Bilaterally symmetrical. See figure 1 Body is triploblastic (having body derived from 3 emboryonic cell layer (ectoderm, mesoderm, endoderm). See figure 2 Body is divided into head, thorax and abdomen ( class: insect). See figure 3 Body is covered with chitinous exoskeleton. Figure 1

12. Figure 2 Figure 3

13. General Characteristic of Arthropod Head bears a pair of compound eyes and antenna. Locomotion takes place by jointed appendages. Digestive system is complete, straight and well developed. See Figure 4 Respiration takes place by general body surface or gills (in Crustaceans) or trachea ( in insects, diplopoda and chilopoda ) or booklungs (Arachnida) and book gills (in king cobra). See Figure 4 Circulatory system is of open type .The blood is colorless. See Figure 4 Excretion takes place through Malphigian tubules (in terrestrial form) or green glands or coxal glands (in aquatic forms). See Figure 4 Nervous system consists of brain and ventral nerve cord. See Figure 4

14. Figure 4

15. General Characteristic of Arthropod Unisexual i.e. sexes are separate. Fertilization is internal or external. They are either oviparous or ovoviviparous. Sensory organ include antennae, sensory hairs for touch and chemoreceptor, simple and compound eyes, auditory organs (in insects) and statocysts (in crustacean).

16. Metamorphosis Change of form or structure in an individual after hatching or birth. Hormones called molting and juvenile hormones, which are not species specific, apparently regulate the changes. These hormone involving growth and differentiation are accompanied by alterations of the organism’s physiology, biochemistry, and behavior . Because development is not the same in all insects, it is convenient to group them into major categories according to the pattern of structural changes: ametabolous, hemimetabolous, and holometabolous .

17. Ametabolous Insect development in which there is no metamorphosis and immature stages appear very similar to the adults, except that they lack genitalia. This kind of development occurs in the silverfish, springtail, and other primitive insects.

18. Hemimetabolous metamorphosis or incomplete metamorphosis The hemimetabolous life cycle consists of egg, nymph, and adult. The nymph, or immature insect, resembles the adult in form and eating habits, differing in size, body proportions, and color pattern. Rudimentary wings are visible and develop externally. Development is gradual through a series of molts (periodic shedding of the outer skeleton), the adult emerging from the final molt. Example (grasshoppers, termites, true bugs)

19. Holometabolous or complete metamorphosis Their life cycle includes four stages: egg, larva , pupa , and adult. The larva differs greatly from the adult. It is wingless, and its form and habits are suited for growth and development rather than reproduction. The change to the adult occurs during the inactive, nonfeeding pupal stage. At this time the larva undergoes a transformation in which the wings appear externally, larval organs and tissues are broken down, and adult structures are developed. metamorphosis is characteristic of beetles, butterflies and moths, flies, and wasps.

20. Complete metamorphosis

21. Type of metamorphosis