Lecture 1: The Importance of Insects to Agriculture & Its Physiology PDF

Lecture 1: Introduction: The Importance of Insects to Agriculture & Its Physiology Marife S. Sayat Faculty, Crop Protection Department BS Agriculture Program Course: ES 9 - Pests, Disease Mana...

Lecture 1: Introduction: The Importance of Insects to Agriculture & Its Physiology Marife S. Sayat Faculty, Crop Protection Department BS Agriculture Program Course: ES 9 - Pests, Disease Management and Protection  Entomology – the study of insects Insects Are animals belonging to phylum Arthropoda or simply arthropods. most abundant and diverse group of organisms on earth Are segmented, bilaterally symmetrical and possess hard chitinous exoskeleton and paired jointed appendages. Course: ES 9 - Pests, Disease Management and Protection  Importance of Insect in Agriculture Insects comprise 75% of all animal species that scientists have named and described, there are about 751,000 described insects (versus 281,000 other animals and 284,000 plants).  Of these the 300,000 described beetles (Coleoptera) are by far the largest group, and most of these insects have wings.  The key to insect success is their ability to survive on land and take to the air. The evolution of wings is an obvious key to insect success and diversity because it means that most insects can disperse widely and escape unfavorable environmental changes. Course: ES 9 - Pests, Disease Management and Protection  The numbers of species in the largest orders of insects:  Coleoptera 300,000  Lepidoptera 200,000  Hymenoptera 130,000  Diptera 110,000 Since these numbers add to 740,000, it can be seen that they comprise the bulk of the Class Insecta. Remember, these numbers are gross estimates only. Indeed, the actual number of insect species is thought to be at least double this figure or greater. The common Orders of insects. Hemiptera (aphids) Siphonaptera (=Psocoptera, booklice, lost wings through evolution) Phthiraptera (lice, an Order that has lost wings through evolution. Hymenoptera (ants, wasps and bees) Diptera, flies (house flies, blow flies, mosquitoes, midges) Siphonaptera (fleas, another Order that has lost wings through evolution) Lepidoptera (moths and butterflies). Course: ES 9 - Pests, Disease Management and Protection  Fields in the study of Entomology  deals with the study of comparative anatomy and the development of an insects form and structure. Course: ES 9 - Pests, Disease Management and Protection   deals with the study of the physical and chemical changes in the insect’s body or the functions of forms and structures. Course: ES 9 - Pests, Disease Management and Protection   the science of classification and identification of insects. Course: ES 9 - Pests, Disease Management and Protection  Products from Insects: Apiculture refers to the rearing of honey bees (Apis millifera) originally for honey, wax and other products (royal jelly) Sericulture refers to the rearing of silkworm (Bombyx mori) for the production of silk. Shellac Stickybrown resinous substance produced from the thick scale of the lac insect (high quality polish, manufacture of insulators, buttons, sealing wax, hairsprays). Course: ES 9 - Pests, Disease Management and Protection  Cochineal is a red dye produced from the dried and powdered bodies of the cactus mealybug (used in foodstuff coloration, cosmetics). Course: ES 9 - Pests, Disease Management and Protection  Economic Importance (Beneficial and Harmful) of Insects Benefits of Insects a. Used as food 1. swarming locust 2. Mole cricket or suhong- Pampanga 3. Termites-Igorots 4. Grubs of Ulalo- by some natives in Mindanao 5. Insect Product- Honey for human food Course: ES 9 - Pests, Disease Management and Protection Course: ES 9 - Pests, Disease Management and Protection Course: ES 9 - Pests, Disease Management and Protection  b. Pollination of flowers - Many plants rely on insect pollinators - Some naturally cross-pollinated annual crops (cucumbers) or perennial fruit crops will have not produce good fruit without the help of insect pollinators. - Plants of economic importance that are pollinated by insects include most vegetables and fruits, along with fiber and hay crops. - Pollinating insects include bees, wasps, butterflies, moths, flies and beetles. Course: ES 9 - Pests, Disease Management and Protection  c. Recycling of organic materials  Decomposition may not be the most glorious role of insects and other arthropods, but it's one of the most important.  many insects species feed on cellulosic plant materials and animal remains.  They help in converting complex organic materials into simpler forms usable again by plants for growth and development. Course: ES 9 - Pests, Disease Management and Protection  d. Control of some insect pests  Some insects feed on other insects.  Predatory insects are dragonflies, lacewings, bugs, tiger beetles, ladybird beetles, mantids, robber flies, ants, bees, and wasps. These insects are predators, either in the adult stage or larvae or at both stages. Some groups of insects are parasitoids. They parasitize the eggs, larvae, or adults of other insects.  Bio-control agents of natural enemies a. predators b. parasitoids Course: ES 9 - Pests, Disease Management and Protection  Bio-control agents of natural enemies a. predators b. parasitoids Course: ES 9 - Pests, Disease Management and Protection  Harmful effects of Insects a. Annoys man- some people especially children are very sensitive to: 1. insect bites 2. contact with hairs of larva. 3. Stings of ants, bees and wasp 4. Reduced quality of stored products b. Destruction of buildings, clothes and other valuable materials c. Transmission of pathogenic microorganisms to man, animals and plants d. Destruction of crops Course: ES 9 - Pests, Disease Management and Protection  Three distinct parts of Insects Course: ES 9 - Pests, Disease Management and Protection  Insect Morphology 1 1 pair of compound 1 pair of antennaeeye simple eyes (ocelli) mouth parts Course: ES 9 - Pests, Disease Management and Protection  Classification based on head position in relation to the long axis of the body: Course: ES 9 - Pests, Disease Management and Protection Course: ES 9 - Pests, Disease Management and Protection  Eyes Compound eyes – located on each side of the head Simple eyes – of most adult insects, located between which consist of many tiny compound eyes on hexagonal elements the front of the known as facets or head, visual ommatidia, each structure with one has its own lens lens for detecting at the front and its own light cluster of light sensing Caterpillar have cells at the back. visual different types of structures with many simple eyes called lenses., photoreceptor stemmata. cells which distinguish brightness and color. Course: ES 9 - Pests, Disease Management and Protection  Mouthparts vary in types depending on the kind of food the insects eat.  a cover which may the lower cover, often referred to as be loosely referred to the lower lip.... as the upper lip. hard, powerful cutting jaws. 'pincers' which are less powerful than a tongue-like the mandibles.... structure in the floor of the mouth. Course: ES 9 - Pests, Disease Management and Protection  Types of Mouthparts: Course: ES 9 - Pests, Disease Management and Protection  Types of Mouthparts: Course: ES 9 - Pests, Disease Management and Protection Course: ES 9 - Pests, Disease Management and Protection Course: ES 9 - Pests, Disease Management and Protection Course: ES 9 - Pests, Disease Management and Protection Course: ES 9 - Pests, Disease Management and Protection  Antennae elongated, segmented structures of varying designs and sizes. are used for sensory purposes and sometimes for defense. Three main parts: 1 the basal segment that articulates with 2 the head capsule 3 2 the second antennal segment. 1 the all remaining 3 “segments” (individually called flagellomeres. Course: ES 9 - Pests, Disease Management and Protection  Types of Antennae: Course: ES 9 - Pests, Disease Management and Protection Course: ES 9 - Pests, Disease Management and Protection Course: ES 9 - Pests, Disease Management and Protection Course: ES 9 - Pests, Disease Management and Protection Course: ES 9 - Pests, Disease Management and Protection Course: ES 9 - Pests, Disease Management and Protection Course: ES 9 - Pests, Disease Management and Protection Course: ES 9 - Pests, Disease Management and Protection Course: ES 9 - Pests, Disease Management and Protection Course: ES 9 - Pests, Disease Management and Protection  2 prothorax mesothorax metathorax Course: ES 9 - Pests, Disease Management and Protection Legs  Are articulated appendages comprising five segments. The insects have five segments of legs: 1. Coxa – the proximal segment that is usually short and stout 2. Trochanter – connects the coxa with femur 3. Femur – the stoutest and sometime the largest segment of the leg, in some instances, it is armed with strong spines 4. Tibia – is often a long, slender structure with downward- pointing spines that aid in climbing. 5. Tarsus – usually made up of several subsegments called tarsomeres, terminate in a pretarsus. Course: ES 9 - Pests, Disease Management and Protection  Types of Legs: 1. Cursorial legs – running legs of roaches 2. Saltatorial – jumping hindlegs of grasshoppers and fleas 3. Fossorial – digging forelegs of mole crickets. 4. Natorial – swimming legs of aquatic insects such as damselflies, dragonflies, mayflies, water beetles. 5. Raptorial – grasping forelegs of preying mantis. 6. Leg of worker honey bee – hindlegs of honeybees used for gathering pollen 7. Clinging legs of lice 8. Clasping legs of aquatic beetles Course: ES 9 - Pests, Disease Management and Protection  Wings Course: ES 9 - Pests, Disease Management and Protection Course: ES 9 - Pests, Disease Management and Protection  Elytra 1 Hindwings Course: ES 9 - Pests, Disease Management and Protection Course: ES 9 - Pests, Disease Management and Protection Course: ES 9 - Pests, Disease Management and Protection Course: ES 9 - Pests, Disease Management and Protection Course: ES 9 - Pests, Disease Management and Protection Course: ES 9 - Pests, Disease Management and Protection  3 Other important parts of Abdomen: Spiracles – these are external openings of the respiratory system found along the side of the thorax and the abdomen. Cerci – slender, pointed structures found on the 11th segments of the abdomen. Tympanum or ear – it is the main auditory organ. Course: ES 9 - Pests, Disease Management and Protection  Important Pest species attacking crop plants in the field belong to the following orders: I. INSECT PESTS A. Chewing Insects-the destructive stage of the pest consuming plants tissues has chewing mouthparts. 1. Lepidoptera (moths, butterflies and skippers) Course: ES 9 - Pests, Disease Management and Protection  2. Coleoptera (weevils and beetles) a. Both larvae (called grubs) and adults have chewing mouthparts 3. Orthoptera (grasshoppers, crickets, katylids) Course: ES 9 - Pests, Disease Management and Protection  4. Isoptera (termites) The termites are principally structural pests attacking wooden parts of a building. A few species attack crops like cassava and coconut. 5.Homoptera (cicadas, leafhoppers, aphids, treehoppers, planthoppers)- Most insect vectors of plant pathogens belong to this order: a. both nymphs and adults suck plant sap. 6. Hemiptera (bugs) a. adults with sucking mouthparts 7. Thysanoptera (thrips, always with s ) 8. Diptera (flies) Course: ES 9 - Pests, Disease Management and Protection  Important Beneficial Insects in the field belong to the following orders: II.BENEFICIAL INSECTS (Pollinators and Natural Enemies) 1. Hymenoptera (bees and wasps) 2. Diptera- some parasitoids and predatory flies belong to this order 3. Neuroptera (lacewings and ant-lion) - Lacewings may be recognized by 2 pairs of wings with highly netted veins producing the appearance of a lace. The wings have extra branches of longitudinal veins and numerous veins: has chewing mouthparts 4. Dermaptera (earwigs) 5. Odonata (dragonflies and damselflies) Course: ES 9 - Pests, Disease Management and Protection 1 – 3. Give the three distinct parts of the Insects. 4 – 8. Give atleat 5 insect orders that are considered as pests. 9– 11. Give atleast 3 reasons why some insects are considered as pests? 12 – 15. Give atleast 4 insect orders that are beneficial to plants and humans.  1 – 3. Give the three distinct parts of the Insects. 1. Head 2. Thorax 3. Abdomen 4 – 8. Give atleat 5 insect orders that are considered as pests. 4. Lepidoptera 5. Coleoptera 6. Orthoptera 12 – 15. Give atleast 4 insect orders that are 7. Isoptera beneficial to plants and humans. 8. Homoptera 12. Hymenoptera Hemiptera 13. Diptera Thysanoptera 14. Neuroptera Diptera 15. Odonata Dermaptera  Insect antennae and its modifications Apr 24, 2020 Yuvraj Singh