GENERAL TERMINOLOGIES ANTERIOR: towards the front (head) of an organism. CHITIN: outer covering which forms an external skeleton DISTAL: away from the body of an organism. DORSAL: the top (back) of an organism. ECDYSIS: casting of exoskeleton LATERAL: the sides of an organism. MEMBRANE: the soft, flexible areas between the sclerites. NOTUM: the dorsal surface of a thoracic segment. POSTERIOR : towards the rear (tail) of an organism. PLEURON: lateral plate between the tergum and sternum PROCTODAEUM: posterior part of the alimentary tract PROXIMAL: near the body of an organism. SCLERITE: individual hardened areas of an insect. STERNUM: the ventral surface of a thoracic or abdominal segment. STOMODAEUM: anterior part of the alimentary tract TERGUM: the dorsal surface of an abdominal segment. VENTRAL: the bottom (belly) of an organism.
HEAD APPENDAGES ANTENNAE COMPOUND EYES (adults only). OCELLI: small pits or bumps between the compound eyes (not on all insects) LABRUM: upper "lip" of insect; located below (anterior of) the clypeus. MANDIBLES: opposable "jaws" of insect; located below (anterior of) labrum. MAXILLAE: food handling structures, located below (anterior of) the mandibles. MAXILLARY PALP: antenna-like structure attached to each maxilla. LABIUM: lower "lip" of insect, located below (anterior of) maxillae. LABIAL PALP: antenna-like structure attached to each side of the labium. THORAX PROTHORAX: thoracic region posterior of the head; contains one pair of legs. MESOTHORAX: thoracic region posterior of prothorax; contains one pair of wings and legs. METATHORAX: thoracic region posterior of mesothorax; contains one pair of wings and legs. WINGS: found on most adult insects, of various shapes and designs. THORAC THO RACIC IC LEG SEGMENT SEGM ENTS S COXA: proximal leg segment, usually quite small. TROCHANTER : very small leg segment between coxa and femur. FEMUR : usually the longest leg segment; between trochanter and tibia. TIBIA: leg segment between the femur and tarsus. TARSUS: distal leg segment; composed of several tarsal segments and a claw. ABDOMEN
HEAD VERTEX: the top (dorsal) region of the head between the compound eyes. FRONS: region of the head below (anterior of) the vertex, above (posterior of) the clypeus, and between the genae.
SPIRACLES: external respiratory openings found on both thorax and abdomen, but much more conspicuous on the abdomen. PROLEGS: fleshy outgrowths used for locomotion, found primarily in larvae of the hymenoptera and lepidoptera. CERCI: antenna-like structure at the very end (posterior) of the abdomen, found in various insect groups. OVIPOSITOR : found at the very end (posterior) of the abdomen in fem ales of various insect groups, variable in shape and size
INSECT’S INTEGUMENT
NERVOUS SYSTEM
Composed of three layers which allows insect to freely move without loss of body defense and protection
- Consists of “ brain” (results from fusion of 3 pairs of ganglia) - A pair of slender connectives cords run, side-by-side from the brain to the end of the insect's abdomen are known as the “ventral nervecord” - These connective cords meet at intervals along the insect's body at the 'ganglia’ - In the most primitive design there is one pair of ganglia per body segment, thus, as the head is made up out of 6 fused body segments, it contains 6 pairs of ganglia, these are collected into 2 groups, each of 3 ganglia, the foremost of which is called the brain and the hindmost the 'subesophageal ganglion'
1. cuticle- composed of bristles and hairs 2. epidermis- a single layer of secretary cells 3. dermis- membrane' which is an amorphous layer about 0.5 micrometres thick. CUTICLE
- relatively thin layer of non-cellular material which lines the external surface of the body as well as lining the tracheae the anterior and posterior sections of the alimentary canal and parts of the reproductive system - it is flexible, elastic and white when first formed and stays this way in many larval forms Sclerotization- chemical processes which result in hardening and darkening of the the cuticle in adult insects
- cuticle can be divided into two layers; 1. epicuticle- which contains no chitin and is highly resistant to water and other solvent 2. procuticle- much thicker and beneath the epicuticle and ca n be divided into two distinct layers a. exocuticle b. endocuticle - consists of a large number of layers of protein and chitin fibres laid down in a laminated pattern such that the individual strands in each layer cross each other thus creating an extremely tough and flexible substance
BREATHING
DIGESTIVE SYSTEM
-Insects have no lungs and breath passively through the spiracles and the air reaches the body by series of smaller and smaller pipes called “trachea” (when their diameter is large) and “ tracheoles” (when their diameter is very small) -Diffusion of gasses is effective over small distances but not over larger ones, this is one of the reasons insects are relatively small -Then number of spiracles an insect has is variable between species however they always come in pairs, one on each side of the body, and usually one per segment -Many insects have valves that allow them to close their spiracles, thus preventing loss of water.
-The -The insect insect digest digestive ive system system is a closed system, with with one one long long enclos enclosed ed tube tube (alimentary canal) running lengthwise through the body. The alimentary canal is a one way street – food enters the mouth and gets processed as it travels toward the anus. Each of the three sections of the alimentary canal performs a different process of digestion salivary glands produce saliva, which travels through salivary tubes into the -The salivary mouth. Saliva mixes with food and begins the process of breaking it down -The first section of the alimentary canal is the foregut or stomodaeum. In the foregut, initial breakdown of large food particles occurs, mostly by saliva. The foregut includes the buccal cavitythe esophagus, and the crop, which stores food before it passes to the midgut - Once food leaves the crop, it passes to the midgut or mesenteron. The midgut is where digestion really happens, through enzymatic action. Microscopic projections from the midgut wall, called microvilli, increase surface area and allow for maximum absorption of nutrients. - In the hindgut or proctodaeum, undigested undigested food particles join uric acid from Malphigian tubules to form fecal pellets. The rectum absorbs most of the water in this waste matter, and the dry pellet is then e liminated through the anus
-The tracheae, which are thin pipes, spread out from the spiracles to reach the whole body, body, with the smallest trac heoles contacting single muscle cells individually -However in most insects the tracheae are all linked through a series of longitudinal pipes called trunks and many smaller connections -Most insects can use their body muscles to squeeze their tracheae and airsacs thus forcing air out, and on release of the muscular tension, drawing fresh air into the large tracheae
CIRCULATORY SYSTEM
-Insects don't have veins or arteries, but they do have circulatory systems. When blood is moved without the aid of vessels, the organism has an open circulatory system. Insect blood, properly called hemolymph, flows freely through the body cavity and makes direct contact with organs and tissues -A single blood vessel runs along the dorsal side of the insect, from the head to the abdomen. In the abdomen, the vessel divides into chambers and functions as the insect heart (14). Perforations in the heart wall, called ostia, allow hemolymph to enter the
blood vessel is not chambered. Like an aorta (7), the vessel simply directs the flow of hemolymph to the head. -Insect blood is only about 10% hemocytes (blood cells); most of the hemolymph is watery plasma. The insect circulation system does not carry oxygen, so the blood does not contain red blood cells Hemolymph is usually green or yellow in color.
IN FOCUS: Above is the different stages of development of the croton bug (Blatella germanic germanica); a); Bottom Bottom is the differer differernt nt stages stages of developm development ent of the oriental oriental roach (Blatta orientalis ) ORDER ORTHOPTERA
-Species -Species of this order have two pairs of wings, the anterior anterior mesothoracic mesothoracic part is thicke thickened ned,, act as covers/ covers/ tegmina for the hinder hinder metath metathora oracic cic pair pair which which is membranous -Antennae is long and filamentous and many jointed -Mouthparts are adapted for chewing -Feeding habits: Feed on starchy or sugary materials but will almost eat anything if necessary IN FOCUS: a. Adult Periplaneta americana americana b. male american cockroach c. stages of development from egg case to different instar of nymph d. female Periplaneta americana e. egg case (ootheca) Top:Oriental,German
ORDER DIPTERA Suborder Nematocera - antennae ( > 8 s egments ) of the adults are longer than the head and thorax - arista is absent, pupal stage are obtectate type FAMILY CULICIDAE
Important species: Culex spp., Aedes spp., Anopheles spp.
IN FOCUS: A. Different larval stages of anopheles, aedes and culex B. Antennae of male male male mosquito showing “hair” “hair” like projections projections (plumose) C. Adult anophelen mosquito ( note of the position of the body when feeding)
Above: An adult Aedes mosquito feeding feeding a blood meal meal Below: An adult Culex mosquito feeding on a blood meal
Below: An adult black fly
humped thorax Below: An adult biting midges feeding (note of the humped thorax )
FAMILY CERATOPHOGONIDAE
- known as biting midges, no-see-ums, punkies
Below: An adult sandfly/owl midges Below: A horse with a “queensland itch/sweet itch” - basically its an allergic response from the saliva of feeding biting midges - this will cause extreme irritation and intense itching which will lead to selfinfliction on horses
Below: An adult horsefly. Take note of the structure of the wings and the elongated body.
Below: An adult Musca domestica. Note the stripes on its thorax.
Below: The external and internal anatomy of the common housefly
Below: Life cycle of housefly. Take note of the stages of larval development
Below: Different pupal development of housefly. Take note if the developing pupa is seen from its puparium.
Below: Stomoxys calcitrans (stable fly). Note of the yellow and dark stripes on the abdomen and thorax. The proboscis is of piercing type for sucking of blood.
Below: Sarcophaga spp ( flesh flies ) Note of the tosselated grey and dark spots on the abdomen.
Below: Blue bottle fly ( Calliphora spp. ) Note of the color of the body and the red color of the eyes.
Below: Green bottle fly ( Lucilla spp. ) Note of the metallic green with coppery or bronze tints color of the body.
Below: Life cycle of the Gasterophilus spp. Note the different site of egg deposition on the body of the horse
Below: An adult horse bot fly and the different stages of development of its larva.
Below: Eggs of the Gasterophilus spp glued to a hair strand
Below: Horse bot fly larvae in the stomach of the horse.
Below: A larva of horse bot fly. Note of the spines located on the abdominal segments of the larva.
Below: Life cycle of sheep nasal fly.
Below: Larvae of sheep nasal fly from necropsied animal.
Below: Larvae of sheep nasal fly
Below: Larvae of tumbu fly
Below: An organ affected with skin maggot fly. fly. The protruding yellow object are actually the larvae feeding the tissue of the organ . Below: An adult Pseudolynchia canariensis
Below: An adult Melophagus ovinus. Note the absence of the wings.
Below: Life cycle of Bed bugs. Note the different nymphal stages.
Below: An adult sheep louse fly on the wool of sheep.
Below: Adult bed bugs. Below: Ctenocephalides canis. Compare the shape of the head to cat flea.
An adult kissing bugs. Can you see the pair of wings? Above: Stick tight flea of the chicken.
Below: Ctenocephalides felis. Note the shape of the head and the arrangement of the ctenidia. Below: Oriental rat flea
