4.1

• Crpt 21 Principles of Crop Protection: Module 4.1 Entomology
• Mannylen C. Alde-Merioles
• Phylum Arthropoda


  Invertebrates, More than 1M species, Arthros=Joint; Podos=Foot, Includes spiders, mites, insects, lobsters, crabs, centipedes and millipedes, Adapted to both aquatic and terrestrial, Economically important arthropods: Insects (Insecta) and Mites (Acari)

  
• Distinguishing Characteristics of Arthropods

  • A segmented body with a head, a thorax, and abdomen segments
  • Appendages on at least one segment
  • A nervous system
  • A hard exoskeleton made of chitin
  • An open circulatory system with hemolymph
  • A complete digestive system with a mouth and an anus
  • Aquatic arthropods use gills to exchange gases while land-living arthropods have internal surfaces that help exchange gasses
• Spiders


  Order Araneae, Have eight legs, chelicerae with fangs, Generally able to inject venom, and spinnerets that extrude silk

  
• Mites


  Eight-legged arthropods, Subclass acari of the class Arachnida, Acarology- study of mites and ticks
• Entomology


  Scientific study of insects including all the phases of their lives and understanding their role in nature, Entomon= "insect"; logio="study of"

  
• Distinguishing characteristics of Insects


  • Three body parts (head, thorax and abdomen)
  • 6 legs (3 pairs)
  • Presence of wings
  • A pair of antennae
  • Varied mouthparts
  • Abdomen with 5-11 visible segments
  • Reproductive appendages are at the tip of the abdomen
  • Exoskeleton-provides protection, muscle attachment, framework and leverage for locomotion
  • Sclerotization -the process of hardening of the cuticle

  
• Insect Head


  Bears the eyes, antennae, and mouthparts, Feeding, sensing, and integrating information from the environment

  
• Insect Compound Eyes


  • Located dorsolaterally on the head, Detects movement and UV light, Allow the insect to view things in a mosaic pattern
• Insect Ocelli


  • Simple eyes that detect motion and light (including UV light) but do not transmit images
• Insect Antennae


  • Sensory function as a tactile organ, organ of smell, and organ of hearing, Scape— the basal segment that articulates with the head capsule, Pedicel — the second antennal segment, Flagellum— all the remaining "segments" (individually called flagellomeres)

  
• Types of Insect Antennae

  • Filiform = long, thin and made of equally sized and shaped segments
  • Moniliform = beaded; The round segments make the antenna look like a string of beads e.g. Beetles
  • Aristate = pouch-like with one lateral bristle
  • Lamellate = nested plates; the segments towards the end are flattened and plate-like. This gives the appearance of a fan e.g. Beetles
  • Clavate = gradually clubbed; the segments become wider towards the tip of the antenna. e.g. Butterflies & Moths and Beetles
  • Pectinate = comb-like; The segments are longer on one side. This gives the appearance of a comb e.g. Sawflies (related to wasps) and Beetles
  • Serrate = sawtoothed; the segments are angled on one side giving the appearance of a saw edge e.g. Beetle
  • Sylate=Similar to filiform antennae, but the terminal segments are pointed and slender, looking like a style e.g. brachycerous flies (Diptera)
  • Plumose = long hairs; the segments each have a number of fine thread-like branches. This gives the appearance of a feather e.g. Flies
  • Geniculate=there is an abrupt bend or elbow part of the way along the antenna e.g. Ants and Beetles
  • Flabellate=similar to pectinate and lamellate antennae, but with thinner and flattener segments (beetles (Coleoptera), wasps (Hymenoptera) and moths (Lepidoptera))
  • Setaceous=bristle-shaped, being thinner and longer in their ends, Example mayflies (Ephemeroptera), dragonflies and damselflies (Odonata)
• Insect Mouthparts


  Vary depending on their feeding habit and the nature of their damage, Two basic types: mandibulate and haustellate or sucking type
• Mandibulate or Chewing Mouthparts

  • Five parts: labrum, mandible, maxillae, labium, and hypopharynx
• Haustellate or Sucking Mouthparts


  • Have no mandibles and do not chew their food, Have an elongated proboscis or beak that allows liquid food to be sucked, Can also pierce or scrape on tissues
• Five Variations of Haustellate Mouthparts


  • Piercing-sucking-has stylets that are needlelike
  • Sponging type, Adapted for sucking up liquid or semiliquid food and found in houseflies and some other flies
  • Siphoning type -for extracting nectar; also have proboscis or tongue, which are the fused maxillae
  • Rasping-sucking -also have proboscis but are short and stout (Ex. thrips)
  • Chewing-lapping -have mandibles used for defense, carrying things, molding wax, and building nests; also have maxillae and labium but they are elongated
• Insect Thorax


  • Bears the locomotor appendages such as wings and legs, 3 segments: prothorax, mesothorax, and metathorax, Combined mesothorax and metathorax are also called the pterothorax

  
• Insect Legs


  • Basic parts are coxa, trochanter, femur, tibia, tarsus, and pretarsus, Types of legs: running, digging or fossorial, grasping or raptorial, catching, pollen collection, jumping or saltatorial, and legs clinging
• Types of Insect Wings

  • Elytra- hard, sclerotized front wings that serve as protective covers for membranous hind wings (Beetles)
  • Hemelytra-front wings that are leathery or parchment-like at the base and membranous near the tip (Hemiptera)
  • Tegmina-front wings that are completely leathery or parchment-like in texture
  • Halteres-small, club-like hind wings that serve as gyroscopic stabilizers during flight
  • Fringed wings-slender front and hind wings with long fringes of hair
  • Hairy wings-front and hind wings clothed with setae
  • Scaly wings-front and hind wings covered with flattened setae (scales) (Lepidoptera)
• Insect Wings


  • Insects are the only arthropods that can fly, Wings are found on the second and third thoracic segments (mesothorax and metathorax), Wing coupling- joining together of two pairs of wings
• Types of Insect Wing Coupling

  • Amplexiform wing coupling-tiny hooks on the hind wings coastal margin, which engaged the forewing on the sclerotized fold along the posterior margin (e.g. Hymenoptera and Trichoptera)
  • Frenuluo-retinacular wing coupling - lobelike process at the base of the forewing, which overlaps the hindwing
  • Jugal wing coupling -an enlarged lobe-like area near the basal posterior margin
• Insect Abdomen


  • 10-11 segments but primitively has 12 segments, 8th to 9th segments of the abdominal segments are composed of the genitalia

  
• Insect Metamorphosis and Development

  • Oviparity development -the egg develops after it has been laid
  • Viviparous- the egg develops inside the female and comes out as a live young
  • Polyembryony -two or more embryos develop from a single egg e.g. hymenopteran such as braconid, encyrtid and dryinid
  • Parthenogenetic- the eggs can grow without being fertilized; eggs develop into an immature stage
  • Ametabolous type- no external changes between molts e.g. collembolans and silverfish
  • Hemimetabolous - incomplete changes; stages include egg, naiad, and adult. Immatures are aquatic, while the adults are terrestrial e.g.dragonfly, damselfly, mayfly, and stonefly
  • Paurometabolous - immatures (nymphs) are strikingly similar to the adults e.g. Orthoptera and Hemiptera
  • Holometabolous - also called complete metamorphosis due to the presence of the three distinct stages the egg, larva, pupa, and adult e.g. Trichoptera, Lepidoptera, Diptera, and Megaloptera