Course Content
Introduction – Definition, position of insects in animal kingdom.
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Introduction
Characters of Class Insecta
FEATURES OF ARTHROPODS
Systematic Classification of Insects
Class: Arachnida (arachnids)
Class: Chilopoda (Centipedes)
Class: Diplopoda (millipedes)
Class: Crustacea (Crustaceans): crabs, shrimp, barnacles, sow bugs, etc.
Class: Insecta (Insects); beetles, bugs, wasps, moths, flies, etc.
Reasons for the dominance of insects over other animals
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DOMINANCE OF INSECTS
REASONS OF DOMINANCE
Some fascinating facts about insects
BENEFICIAL AND HARMFUL EFFECTS OF INSECTS
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Beneficial effects
Detrimental effects
External morphology: Body regions, external processes, cuticle
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Body segmentation of Insect
Insect Body wall/Integument/Exoskeleton
Cuticle
Principle Layers of the Cuticle
Epidermis
Molting
Insect Head
Types of head or orientation of Head
Insect Antennae
MODIFICATIONS OF INSECT ANTENNAE
MOUTH PARTS
Parts of Mouth
Modification of mouth parts
MANDIBULATE MOUTH PART
PIERCING-SUCKING MOUTHPARTS
RASPING AND SUCKING MOUTH PARTS
CHEWING AND LAPPING TYPE
SIPHONING TYPE
SPONGING TYPE
CUTTING AND SPONGING TYPE
Visual Organs or Photoreceptor
Difference between Simple Eyes and Compound Eyes
THORAX AND THORACIC SEGMENTS AND ITS APPENDAGES
Structure of legs
Modification of legs
Other forms of modification of legs
WINGS
Wing venation
Wing adaptations and modifications
Abdominal Appendages
Some parts of Post genital appendages
Internal Anatomy
Digestive, Reproductive (Male and Female), Respiratory, Circulatory, Nervous and Excretory Systems.
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DIGESTIVE SYSTEM OF INSECTS
Salivary glands
Process of digestion
Digestive enzymes
Modification of digestive system of insects.
CIRCULATORY SYSTEM OF INSECTS
Dorsal blood vessel
Accessory pulsatile organs
Process of blood circulation
Properties of blood
Functions of blood
EXCRETORY SYSTEM OF INSECTS
RESPIRATORY SYSTEM OF INSECTS
Classification of tracheal system based on the number and arrangement of functional spiracles
Other types of respiration
REPRODUCTIVE SYSTEM IN INSECTS
Female reproductive system
Male reproductive system
Types of Reproduction
NERVOUS SYSTEM OF INSECTS
Classification of Nervous System
Insect Metamorphosis and Development
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Introduction
Types of Metamorphosis
Types of Larvae
Quiescence and Diapause
Classification and Study of Economically Important Orders and Families of Insects
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Classification of insects
EXOPTERYGOTA (Simple body change during growth)
ENDOPTERYGOTA (Complex body change during growth)
INSECT ORDERS OF ECONOMIC IMPORTANCE
Families of economic importance
ORDER: HOMOPTERA
Families of economic importance
COLEOPTERA
Economically important families
ORDER: DIPTERA
Economically important families
ORDER: HYMENOPTERA
Economic important families
ORDER: LEPIDOPTERA
Economically important families
Moths (Heterocera)
Introduction to Industrial Entomology: Apiculture, Sericulture, Lac culture.
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Life cycle of Honeybee (Apis milifera )
Life cycle of silkworm (Bombyx mori Linnaeus )
Life Cycle of Lac Insect ( Kerria lacca)
Learn Introductory Entomology with Rahul
About Lesson

Visual Organs or Photoreceptor

Photoreceptors of insects include

  1. Compound eyes
  2. Simple eyes or dorsal ocelli
  3. Lateral ocelli or stemmata

 

 

  1. Compound eyes:
  • They are found in nearly all adults and many immatures of ametabolous and hemimetabolous orders.
  • Compound eyes are composed of many similar, closely packed facets (called ommatidia) which are the structural and functional units of vision.
  • The number of ommatidia varies considerably from species to species: some worker ants have fewer than six while some dragonflies may have more than 28,000.
  • Primary pigment cells (or) Iris pigment cells: These are darkly pigmented cells, commonly two in number, present around the crystalline cone which is mainly useful for separating the ommatidia from one another and also rrestrictsthe movement of light passing from the neighboring ommatidia.
  • The light-sensitive part of an ommatidium is called the rhabdom consisting of closely packed micro-tubules where light-sensitive pigments (e.g. rhodopsin, etc.) are stored.
  • Most diurnal insects have pigment cells surrounding each ommatidium.
  • Nocturnal and crepuscular (those that are active primarily during twilight -i.e., dawn and dusk) insects have pigment cells that do not completely isolate each facet. They can detect polarization patterns in sunlight, and discriminate wavelengths in a range from ultraviolet to yellow (but not red).

 

  1. Simple eyes or dorsal ocelli:
  • Two types of “simple eyes” can be found in the class Insecta: dorsal ocelli and lateral ocelli (=stemmata). Although both types of ocelli are similar in structure, they are believed to have separate phylogenetic and embryological origins.
  • Dorsal ocelli are commonly found in adults and the immature stages (nymphs) of many hemimetabolous species.
  • They differ from compound eyes in having only a single corneal lens covering an array of several dozen rhabdom-like sensory rods.
  • Lateral ocelli (=stemmata) are the sole visual organs of holometabolous larvae and certain adults (e.g. Collembola, Thysanura, Siphonaptera, and Strepsiptera).
  • Larvae use these simple eyes to sense light intensity, detect outlines of nearby objects, and even track the movements of predators or prey.
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