Insect Nervous System PDF

LESSON 4: INSECT NERVOUS AND SENSORY SYSTEMS \"All Right Mr. DeMille, I\'m Ready For My Close-Up\" by Dixie Native Photo courtesy: Dixie Natrive/Flickr. Taken from +-----------------------------------+-----------------------------------+ | Module No. and Title | Module 1: Basic of in...

LESSON 4: INSECT NERVOUS AND SENSORY SYSTEMS \"All Right Mr. DeMille, I\'m Ready For My Close-Up\" by Dixie Native Photo courtesy: Dixie Natrive/Flickr. Taken from +-----------------------------------+-----------------------------------+ | Module No. and Title | Module 1: Basic of insect | | | physiology and anatomy | +===================================+===================================+ | Lesson No. and Title | Lesson 4: Insect Nervous and | | | Sensory Systems | +-----------------------------------+-----------------------------------+ | Learning Outcomes | After learning the course, you | | | will be able to: | | | | | | 1. Discuss the structures and | | | provide the individual | | | functions of each organ | | | associated with the insect | | | nervous system | | | | | | 2. Explain the structures and | | | functions related to the | | | insect sensory system | | | | | | 3. Discuss the use of pheromones | | | in insect pest management | +-----------------------------------+-----------------------------------+ | Time Frame | Weeks 7 and 8 | +-----------------------------------+-----------------------------------+ | Introduction | Welcome to Lesson 4 of Module 1! | | | In this lesson, you will deal | | | with the basic structures and | | | functions of insects\' nervous | | | and sensory systems. You will | | | study the roles these systems | | | played in allowing insects to | | | survive a hostile environment and | | | explain the mechanisms that | | | involve surviving such | | | conditions. Moreover, one crucial | | | application in this lesson is | | | pheromones\' use for the | | | ecological management of insect | | | pests in the field. I hope you | | | will have a good time reading and | | | doing the lesson\'s activity and | | | application sections. Good luck | | | to you. | +-----------------------------------+-----------------------------------+ | Activity | In your activity notebook, draw | | | and label the parts of the | | | following structures: | | | | | | 1\. Insect brain or | | | supraesophageal ganglion | | | | | | 2\. Ventral nerve cords | | | | | | 3\. Nerve cells | | | | | | 4\. Trichoid sensilla | | | | | | 5\. Tympanum | | | | | | 6\. Ommatidium | +-----------------------------------+-----------------------------------+ | Analysis | 1. What is a ganglion? What | | | function does it play in the | | | nervous system of insects? | | | | | | 2. What are the specific organs | | | involved in the detection of | | | chemicals in the atmosphere | | | among insects? | | | | | | 3. How does information from | | | sensory organs are | | | transmitted to the brain and | | | activates muscle tissue as a | | | response to stimuli? | | | | | | 4. What is the importance of | | | pheromones and why they are | | | an essential component of | | | pest management? | +-----------------------------------+-----------------------------------+ | Abstraction | **INSECT NERVOUS SYSTEM** | | | | | | 1. The insect nervous system is | | | similar to the higher animal | | | functions to detects, | | | transmits, and interprets | | | information from the outside | | | world. Although they are | | | mostly small, insects have a | | | sophisticated nervous, which | | | better give them a high | | | chance of survival. | | | | | | **Structures of the Nervous | | | System** | | | | | | **A. The nerve cells of neurons** | | | | | | 2. It is the basic unit in the | | | study of the nervous system. | | | This structure is responsible | | | for receiving information | | | from the outside environment, | | | sending information to other | | | cells, or activating muscles | | | to perform their tasks. | | | | | | **The nerve cells have three | | | major parts:** | | | | | | \(a) Dendrite -- receive | | | information from the outside | | | environment where they are | | | positioned perfectly to major | | | sensory organs of insects | | | (e.g., antennae, mouthparts, | | | and various parts of the body) | | | and other nerve cells. | | | | | | \(b) Cell body -- also known as | | | the soma and possess nucleus | | | where it receives information | | | from the dendrite. | | | | | | \(c) Axon -- receives | | | information from the cell body | | | and transmits this information | | | to other neurons or the target | | | tissues/organs. The axon is | | | considered the longest part of | | | the nerve cell, as shown in | | | Figure 44. | | | | | |  | | | | | | Figure 44. The structure and | | | parts of a typical nerve cell. | | | Photo courtesy by Onlea. Taken | | | from Faculty of Science (2015), | | | University of Alberta. Accessed | | | July 3, 2020. | | | | | | **TYPES OF NERVE CELLS/NEURON** | | | | | | \(a) **Sensory neurons** | | | transmit signal/information | | | from the sensory organs, which | | | react to stimuli from the | | | environment and forward such | | | information to the central | | | nervous system for processing. | | | Here, the signal will travel | | | from dendrite to the cell body | | | before reaching the axon, as | | | shown in Figure 45. | | | | | | \(b) **Motor or association | | | neurons** transmit | | | signal/information from the | | | central nervous system to the | | | muscle organs of the insect | | | body for them to respond to the | | | stimuli. Here, the signal | | | travels only along the axon, | | | originating along a collateral | | | branch and usually does not | | | pass through the cell body. | | | | | | \(c) **Interneuron** -- transmit | | | signal/information from one | | | neuron to another neuron | | | | | |. | | | | | | Figure 45. The sensory and motor | | | neuron is showing the direction | | | of signals/impulses. Photo | | | courtesy: Elzinga (1978). Date | | | access: July 23, 2020. Taken from | | | the book of Elzinga (1978). | | | Fundamentals of Entomology. | | | Department of Entomology. Kansas | | | State University, Prentice Hall | | | Inc., Englewood Cliffs, New | | | Jersey 07632. | | | | | | **ACTION POTENTIAL/NERVE | | | SIGNALS** | | | | | | 3. It is an electrochemical | | | message of the nerve cell. | | | Action potential happens by | | | changing the frequency of | | | signal conduction. | | | | | | 4. Neuron\'s plasma membrane has | | | a voltage, which is known as | | | the membrane potential, | | | wherein the inside of the | | | cell is negative due to a | | | high amount of anion (which | | | has a negative charge) | | | relative to the outside due | | | to the high amount of sodium | | | ion. | | | | | | 5. When neurons are at rest, | | | there is an active transport | | | channel in the neuron\'s | | | plasma membrane pump (Figure | | | 46): | | | | | | 6. Sodium ions (Na+) are moving | | | out of the cell. | | | | | | 7. Potassium ions (K+) are | | | moving inside of the cell. | | | | | | 8. A higher amount of sodium ion | | | is moving out of the cell, | | | while less potassium is | | | moving inside the cell. | | | | | | 9. The result is a negative | | | charge inside the cell. The | | | cell membrane is now | | | polarized, as shown in | | | Figure 46. | | | | | |  | | | | | | Figure 46. The sodium-potassium | | | exchange pump occurring in the | | | neuron\'s cell membrane. Photo | | | courtesy: slideplayer.com. Date | | | accessed: August 14, 2020. Taken | | | from | | | [[https://cutt.ly/Nd3dvC2]{.under | | | line}](https://cutt.ly/Nd3dvC2) | | | | | | 10. Resting potential refers to | | | the charge that exists across | | | a neuron\'s membrane while at | | | rest. The charge is -70 mV. | | | Resting potential is the | | | starting point for action | | | potential (Figure 47). | | | | | | Figure 47. Close-up view of the | | | axonic membrane showing the | | | negative charge inside and | | | positive outside during resting | | | potential. Negative inside due to | | | the high amount of anions while | | | positive outside the cell | | | membrane due to the high sodium | | | ion. Photo courtesy: | | | slideplayer.com. Date accessed: | | | August 14, 2020. Taken from | | | [[https://cutt.ly/Nd3dvC2]{.under | | | line}](https://cutt.ly/Nd3dvC2) | | | | | | - The action potential shall | | | start when there is pressure | | | or stimuli that disturb the | | | sensory organ of insects. The | | | action potential causes the | | | opening of the sodium | | | channels in the neuron\'s | | | dendrite. | | | | | | - Then, the sodium ions flood | | | into the neuron, and the | | | membrane is depolarized -- | | | more positive inside than | | | outside (reversal of charge, | | | Figure 48). | | | | | | Figure 48. A reversal of charge | | | from positive outside to negative | | | inside or vice versa due to the | | | opening of the sodium gate in the | | | axonic membrane, thus flooding | | | the interior of the cell with | | | sodium ions. A reversal of charge | | | is happening during an action | | | potential. Photo courtesy: | | | slideplayer.com. Date accessed: | | | August 14, 2020. Taken from | | | [[https://cutt.ly/Nd3dvC2]{.under | | | line}](https://cutt.ly/Nd3dvC2) | | | | | | - The nerve impulse will travel | | | in the neuron\'s dendrite and | | | axon membrane as more sodium | | | ion is moving inside the | | | cell, changing the charge | | | from negative to positive. | | | The moving in and out of the | | | ion in the cell membrane is | | | via the voltage-gated | | | channels. These channels are | | | protein channels found in the | | | membrane that will open and | | | closes in response to the | | | electrical charge. | | | | | | - The reversal in voltage from | | | negative to positive is what | | | we called the action | | | potential. An action | | | potential is a quick | | | depolarization of the | | | neuron\'s membrane. | | | | | | - There will be changes in the | | | membrane potential from -70 | | | mV to +35 mV. | | | | | | - When the action potential has | | | passed, the voltage-gated | | | channels are closed, and the | | | resting potential is | | | restored. | | | | | | - The membrane potential | | | quickly returns to -70 mV | | | during the repolarization | | | phase. | | | | | | - The action potential is a | | | brief, quick depolarization | | | of a neuron\'s plasma | | | membrane, which carries | | | information along axons. | | | | | | - Once the action potential was | | | started, it will continue | | | until it reaches its final | | | destination, the muscle cell. | | | | | | Further discussion on action | | | potential is presented from the | | | youtube video presentation of Dr. | | | Larry Keeley that you can access | | | from this link | | | [[https://cutt.ly/NshuqJU]{.under | | | line}](https://cutt.ly/NshuqJU). | | | | | | **SYNAPSE** | | | | | | - This is gaps between two | | | neurons, that is, between the | | | axon of one neuron and | | | dendrite of the next neuron. | | | | | | **Types of Synapse** | | | | | | **1. Electrical synapses** - are | | | points where ionic currents flow | | | directly across the synapse from | | | one neuron to another. This type | | | of synapse has no time lag, which | | | is very crucial in escaping | | | reactions among insects. For | | | instance, | | | | | | **2. Chemical Synapse**s -- the | | | most common type of synapse among | | | insects. Under chemical synapse, | | | we need to define the following | | | terms further: | | | | | | **Presynaptic neurons** - bring | | | action potentials toward the | | | synapse. | | | | | | **Postsynaptic neurons** - carry | | | action potentials away from the | | | synapse. | | | | | | **Synaptic cleft** - is the small | | | gap between the two neurons. | | | | | | **NEUROTRANSMITTERS** | | | | | | - These are chemical messengers | | | that carry the message of the | | | nerve impulse across the | | | synapse. | | | | | | - Neurotransmitters such as | | | acetylcholine are released | | | into the synapse and bind | | | with receptors on the | | | postsynaptic cell membrane, | | | which causes ion channels to | | | open in the new cell (Figure | | | 49). | | | | | |  | | | | | | Figure 49. The postsynaptic | | | neuron, where the | | | neurotransmitter that was carried | | | from presynaptic neurons, will | | | enter the neurotransmitter | | | receptor along the postsynaptic | | | membrane. Photo courtesy: | | | slideplayer.com. Date accessed: | | | August 14, 2020. Taken from | | | [[https://cutt.ly/Nd3dvC2]{.under | | | line}](https://cutt.ly/Nd3dvC2) | | | | | | **Mechanism of how | | | neurotransmitter works in the | | | synapse:** | | | | | | - When the action potential has | | | reached the presynaptic | | | neuron or axon terminal, the | | | voltage-gated Calcium ion | | | channels open. This causes | | | the influx of calcium ion | | | inside the cell, which | | | signals the vesicles | | | containing the | | | neurotransmitter to move to | | | the membrane. The presence of | | | Ca ion induces vesicular | | | exocytosis, thereby releasing | | | the neurotransmitter | | | acetylcholine. | | | | | | - When the acetylcholine was | | | already released, it will | | | bind to the postsynaptic | | | neuron\'s receptor, causing | | | chemically-gated ion channels | | | to open and cause | | | postsynaptic membrane | | | excitation. | | | | | | - This causes the transfer of | | | action potential to the next | | | neuron and will continue | | | throughout the last neuron. | | | | | | - When acetylcholine performs | | | its task, it has to be | | | inactivated by a vital enzyme | | | in the synapse, called the | | | acetylcholinesterase. | | | | | | - Acetylcholinesterase breaks | | | acetylcholine into non-toxic | | | acetate and choline. | | | | | | - The choline will be | | | reabsorbed back into the | | | presynaptic neuron to be used | | | to synthesize acetylcholine, | | | and then stored back in | | | vesicles waiting for the next | | | action potential to happen, | | | as shown in Figure 50. | | | | | | https://www.philpoteducation.com/ | | | pluginfile.php/1205/mod\_book/cha | | | pter/2869/6.2.5a-tags.jpg | | | | | | Figure 50. Mechanism of action | | | potentials\' movement in the | | | synapse through the action of the | | | neurotransmitter. Photo courtesy: | | | Philpot education. Date accessed: | | | July 25, 2020. Taken from | | | [[https://cutt.ly/ZsoMGfd]{.under | | | line}](https://cutt.ly/ZsoMGfd) | | | | | | **Kinds of Synapses** | | | | | | 1. **Excitatory synapse** -- the | | | receptor protein is a | | | chemically gated sodium | | | channel (it is opened by a | | | neurotransmitter, e.g. | | | acetylcholine). | | | | | | - When opened, sodium rushes in | | | and an action potential | | | begins in the new neuron. | | | | | | 2. **Inhibitory synapse** -- the | | | receptor protein is a | | | chemically gated potassium | | | channel. | | | | | | - When opened, potassium ions | | | leave the cell which | | | increases the negative charge | | | and inhibits the start of an | | | action potential. | | | | | | **B. The Central Nervous System | | | (CNS)** | | | | | | - The CNS is composed of the | | | brain or supraesophageal | | | ganglion and the ventral | | | nerve cord, including the | | | subesophageal ganglion, | | | thoracic and abdominal | | | ganglia (Figure 51). | | | | | |  | | | | | | Figure 51. The central nervous | | | system of insects. Adapted from | | | the Nervous system of an insect | | | by Kumar, A. Date accessed: July | | | 25, 2020. Taken from | | | [[https://cutt.ly/dspty9Q]{.under | | | line}](https://cutt.ly/dspty9Q) | | | | | | **The Brain or Supraesophageal | | | ganglion** | | | | | | - Supraesophageal ganglion | | | (brain) is located above the | | | esophagus (Figure 52). | | | | | | **The brain consists of:** | | | | | | 1\. Protocerebrum (first pair of | | | lobes) controls the compound | | | eyes and the simple eyes | | | (ocelli). | | | | | | 2\. Deutocerebrum (Second pair | | | of lobes), controls the | | | activities of the insect | | | antennae. | | | | | | 3\. Tritocerebrum (Third pair of | | | lobes), controls the frontal | | | ganglion, labrum and | | | subesophageal ganglion. | | | | | | Figure 52. The insect brain and | | | some important nervous | | | structures. Photo courtesy: | | | Elzinga (1978). Date access: July | | | 23, 2020. Taken from the book of | | | Elzinga (1978). Fundamentals of | | | Entomology. Department of | | | Entomology. Kansas State | | | University, Prentice Hall Inc., | | | Englewood Cliffs, New Jersey | | | 07632. | | | | | | **The Ventral Nerve Cord** | | | | | | - The first ganglion in the | | | ventral chain is the | | | subesophageal ganglion, | | | located below the esophagus; | | | hence its name received | | | nerves and controls the | | | activities of the mandibular, | | | maxillary and labial segments | | | of the insect mouth. | | | | | | - There are typically three | | | thoracic ganglia, but in some | | | insects, they fuse to form a | | | single ganglion. | | | | | | - The abdomen often merges to | | | form a single abdominal | | | ganglion or combine it to the | | | thoracic ganglion, as in the | | | house fly (Figure 53). | | | | | | Figure 53. A comparison between | | | the nervous system structure of | | | bristletail (primitive insect) | | | and a housefly (advanced insect). | | | Photo courtesy: Weebly. Date | | | accessed July 24, 2020. Photo | | | taken from | | | [[https://cutt.ly/7srgqSx]{.under | | | line}](https://cutt.ly/7srgqSx) | | | | | | **INSECT SENSORY SYSTEM** | | | | | | - Insects have developed keen | | | sense organs that allow them | | | to locate mates and foods, | | | avoid predation/parasitism, | | | build houses, and communicate | | | different communications | | | cues. | | | | | | · | | | | | | **The primary sense organs of | | | insects are those involved in | | | smell, touch, vision, taste, and | | | hearing are classified into:** | | | | | | a\. Mechanoreceptors | | | | | | b\. Photoreceptors | | | | | | c\. Thermoreceptors | | | | | | d\. Chemoreceptors | | | | | | **MECHANORECEPTORS** | | | | | | - Also, known as sensilla, are | | | the most abundant sensory | | | receptors most seen in the | | | entire insect body surface. | | | There are various sizes of | | | the mechanoreceptor: | | | | | | 1\. hair-like (trichoid | | | sensilla) | | | | | | 2\. domelike (campaniform | | | sensilla) | | | | | | 3\. platelike (placoid sensilla) | | | | | | **There are 3 main types of | | | mechanoreceptors:** | | | | | | **(1) Tactile** receptors are | | | sensitive to touch, such as | | | hairs, bristles, and setae in the | | | body of insects. These are thin | | | cuticle that attaches directly to | | | the nerve cells or neuron. So | | | whenever these structures were | | | disturbed, then this will produce | | | an action potential. They can be | | | found in the antennae, tarsi, | | | tibia, and cerci of insects. | | | Figure 54 shows the structure of | | | a trichoid sensillum showing the | | | various cellular and non-cellular | | | parts. | | | | | | Figure 54. The structures and | | | parts of a trichoid sensillum. | | | Photo courtesy Cronodom.com. Date | | | Accessed July 24, 2020. Taken | | | from | | | [[https://cutt.ly/LswlWxu]{.under | | | line}](https://cutt.ly/LswlWxu) | | | | | | **The sensory cells in the | | | Trichoid sensillum:** | | | | | | \(a) the tormogen cell secretes | | | the socket. | | | | | | \(b) the trichogen cell secretes | | | the seta. | | | | | | \(c) the thecogen cell (or | | | sheath cell) secretes the | | | scolopale sheath. | | | | | | \(d) the glial cell wraps around | | | the axon. | | | | | | **(2) Proprioceptors** -- these | | | receptors are designed to detect | | | the relative position of | | | particular body parts compared to | | | another body part and the | | | relative position of the insect | | | into its environment (gravity). | | | Please take note that there are | | | no external structures associated | | | with them. They are just lying | | | below the intact cuticle and | | | epidermal cells. Some examples of | | | proprioceptors are as follows: | | | | | | **(a) Hair plate** --are often | | | positioned next to folds within | | | the cuticle, so that the | | | deflection of the hairs signals | | | the movements of one | | | joint-segment relative to the | | | adjacent segment. They are | | | located on the joints and neck of | | | insects (Figure 55). | | | | | | Figure 55. Schematic | | | cross-section of a hair plate. | | | Photo courtesy: Lambdaloop - Own | | | work, CC BY-SA 4.0, Date | | | Accessed: July 24, 2020. Taken | | | from: | | | [[https://cutt.ly/hswCOdE]{.under | | | line}](https://cutt.ly/hswCOdE) | | | | | | **(b) Campaniform sensilla** | | | --located on joints or on areas | | | that are subject to distortion. | | | They cannot be seen externally | | | but recognized from their | | | dome-shaped cuticle areas. They | | | occur in different parts of the | | | insect body, such as in the wing | | | bases, cerci, halteres, palps, | | | bases of trochanter, femur, | | | tibia, or tarsal segments (Figure | | | 56). | | | | | | Figure 56. A campaniform | | | sensillum found in a cockroach. | | | Photo courtesy Moran et al. | | | (1971). Date access: July 24, | | | 2020. Taken from | | | [[https://cutt.ly/7swYlMo]{.under | | | line}](https://cutt.ly/7swYlMo) | | | | | | **(3) Sound receptors --** detect | | | pressure waves in air and water. | | | Across all insects, the range of | | | sound detected is between from 1 | | | hertz to 100 kilohertz. This is | | | far more sensitive than a human | | | ear that can only detect sounds | | | from 20 hertz to 20 kilohertz. | | | The principal sound receptors | | | are: | | | | | | C**hordotonal organ** -- consist | | | of a single unit or group of | | | similar units called scolopidia. | | | They are present in the femur, | | | distal tibia, tarsal region, | | | abdomen, and wing base. The | | | scolopidia is composed of 3 | | | cells: the nerve cell, the | | | scolopale cell, and the cap cell | | | (Figure 57). | | | | | | Figure 57. A typical | | | representation of a Chordotonal | | | organ. Note that they are | | | connected to an intact cuticle | | | (top and below). Photo courtesy: | | | Kavlie and Albert (2013). Date | | | accessed: July 24, 2020. Taken | | | from: | | | [[https://cutt.ly/tswFX9u]{.under | | | line}](https://cutt.ly/tswFX9u) | | | | | | **Special Types of chordotonal | | | Organ** (Figure 58). | | | | | | \(a) **tympanum** -- use to | | | detect sound at a longer | | | distance. They are consists of | | | a thin membrane located over a | | | tracheal tube. They can be | | | located depending on the | | | species but usually found in | | | the abdomen, legs, metathorax, | | | ventral thorax, wing base, | | | prosternum, or cervix (neck). | | | Figure 58 shows the structure | | | and location of the tympanum on | | | insects. | | | | | | **(b) Johnston organ** is usually | | | located in the insect antennae | | | pedicel, especially among male | | | mosquitoes and other dipterans | | | insects. This organ detects sound | | | waves from wing beats commonly | | | used to find a mate. | | | | | | Figure 58. On top is the Johnston | | | organ in the antennae (pedicel, | | | 2nd antennal segment) of male | | | mosquitoes. Below is the tympanum | | | from the cicada and grasshoppers | | | located on various parts of the | | | body. On the left is the | | | scolopale/scolophore organ | | | showing the components. Photo | | | courtesy from Encyclopedia | | | Britannica, Inc. (2012). Date | | | access: July 24, 2020. Taken | | | from: | | | [[https://cutt.ly/KswYIAp]{.under | | | line}](https://cutt.ly/KswYIAp) | | | | | | - These organs in the insect | | | body are responsible for | | | sensing of light, and when | | | images are produced, | | | converted into sight. | | | | | | - The major organs involved in | | | photoreception are the | | | following: | | | | | | **(1) Compound eyes** --is | | | composed of several individual | | | units called ommatidium/ommatidia | | | (plural form). Have the ability | | | to form an image with high | | | sensitivity to light intensity. | | | It is composed of the following | | | parts: | | | | | | \(a) corneal lens | | | | | | \(b) crystalline cone | | | | | | \(c) Rhabdom | | | | | | \(d) Retinula cells | | | | | |      | | | | | | Figure 59. The compound eyes and | | | their parts. The corneal lens and | | | crystalline cone are the | | | [light-gathering | | | apparatus], while the | | | rhabdom, retinular cells, and | | | pigment cells comprise the | | | [light-sensing | | | apparatus]. Photo | | | courtesy: Kaelyndwyer. Date | | | accessed: July 24, 2020. Taken | | | from | | | [[https://cutt.ly/KseNTuv]{.under | | | line}](https://cutt.ly/KseNTuv) | | | | | | \(a) **Apposition compound | | | eyes** -- each ommatidium focus | | | on rays that are almost | | | parallel to its long axis, so | | | that each forms an image of | | | only a tiny part of the visual | | | field. The image of the whole | | | is the result of the | | | combination of these part | | | images. This is the type of | | | compound eye for diurnal | | | insects (day-active insects). | | | | | | \(b) **Superposition compound | | | eyes** -- the sensory cells of | | | the ommatidium pick up light | | | from a more substantial part of | | | the visual field. The image | | | received overlaps those | | | received by as many as 30 | | | neighboring ommatidia. Image | | | gains in brightness but loses | | | in sharpness compared with the | | | apposition eyes. This is the | | | type of compound eyes for | | | nocturnal insects | | | (night-active). | | | | | | 2\. **Simple Eyes** -- also | | | known as ocelli -- found in | | | both immature and adult | | | insects, but unlike compound | | | eyes, they have low revolving | | | power. This may be present or | | | absent on insects (Figure 61). | | | | | | Figure 61. Three simple eyes of a | | | cicada (red, pointed by arrow | | | sign) are seen in between two | | | compound eyes. Photo courtesy: | | | buzzfeed.com. Date accessed: July | | | 24, 2020. Taken from: | | | [[https://cutt.ly/jse2I0L]{.under | | | line}](https://cutt.ly/jse2I0L) | | | | | | Figure 62. Cross-section of the | | | insect ocellus. Photo courtesy: | | | Evergree.edu. Date accessed: July | | | 24, 2020. Taken from: | | | [[https://cutt.ly/rse96Jo]{.under | | | line}](https://cutt.ly/rse96Jo) | | | | | | **(3) Stemmata** -- found in | | | larvae of some insects, | | | particularly in the larvae of | | | Lepidoptera. There are two or | | | more of this structure. They can | | | detect light/darkness and motion | | | but having low revolving power. | | | | | | Figure 63. The stemmata on the | | | head of a tobacco hornworm (as | | | indicated by arrow). Photo | | | courtesy: Jonathan Neal. Date | | | Accessed: July 24, 2020. Taken | | | from: | | | [[https://cutt.ly/sse4oBK]{.under | | | line}](https://cutt.ly/sse4oBK) | | | | | | - These detect heat or changes | | | in temperature. If present, | | | thermoreceptors are usually | | | found in the antennae, in the | | | legs (American cockroach), | | | and the well-studied | | | mesothoracic region from the | | | beetle *Melanophila.* | | | | | | - The beetle uses this receptor | | | to monitor forest fire. When | | | detected, the female insect | | | immediately flies towards the | | | newly burned forest and lays | | | her eggs on the charred wood. | | | The egg\'s chorion is so hard | | | and will not succumb to the | | | heat from a forest fire. This | | | is a more significant | | | advantage for survival | | | because there are no natural | | | enemies in the area, and the | | | emerging grub shall have an | | | ample food supply when hatch. | | | | | | Figure 64. A diagrammatic | | | representation of a jewel beetle, | | | Melanophila is flying towards a | | | newly burnt forest to lay eggs. | | | The burning is detected by the | | | thermoreceptor located in the | | | metathoracic region of the | | | insect. Photo courtesy: Corky\'s | | | blog. Date accessed: July 26, | | | 2020. Taken from: | | | [[https://cutt.ly/rsjBFvx]{.under | | | line}](https://cutt.ly/rsjBFvx) | | | | | | **CHEMORECEPTORS** | | | | | | - This type of receptor is the | | | most critical cues, | | | particularly for those | | | insects that are active at | | | night or having nonfunctional | | | photoreceptors. | | | | | | - Involves the detection of | | | airborne chemicals; hence, | | | chemoreceptors involve two | | | senses, the sense of smell | | | and taste. | | | | | | Figure 65. A wasp showing the | | | body parts possessing gustatory | | | (taste) receptors (located in the | | | wings, mouthparts, legs, | | | ovipositor) and olfactory (smell) | | | receptors (antenna, maxillary | | | palp) Photo courtesy: Jawwad | | | Mirza. Slideshare. Taken from: | | | [[https://cutt.ly/3sjNzKI]{.under | | | line}](https://cutt.ly/3sjNzKI) | | | | | | - The most crucial organ for | | | these receptors is the | | | antennae, mouthparts, and the | | | tarsi. | | | | | | - Chemoreceptors respond to | | | food sources, predators or | | | from competitors, and | | | conspecifics | | | | | | - The chemical cues used by | | | insects for communication are | | | the PHEROMONES and have many | | | uses. | | | | | | **PHEROMONES** | | | | | | **A. History and development of | | | pheromones** | | | | | | - 1870s - French naturalist | | | Jean-Henri Fabre was thrilled | | | when a female great peacock | | | moth emerged from a cocoon on | | | his study table. At around 9 | | | PM, he observed abundant male | | | peacock moth of the same | | | species surrounding his | | | office where the female moth | | | is located. Fabre concluded | | | that there is something in | | | the female moth that the male | | | moth is so attracted to. | | | | | | - Joseph A. Lintner, New York | | | entomologist just like | | | Fabre\'s observation, | | | observed that male moths of | | | the same species crowded the | | | spicebush silk moths from his | | | window sill. He concluded | | | then that the female | | | spicebush moth releases a | | | specific compound that the | | | male moth is so attracted to. | | | Moreover, he also foresaw | | | that the chemicals could be | | | used by people to manage | | | pests of crops. | | | | | | - 1930s - Adolph Butenandt, a | | | German chemist, pioneered the | | | work on pheromone using the | | | silkworm as a test insect. | | | After three decades in 1959, | | | he successfully isolated the | | | alluring chemical and named | | | it bombykol. | | | | | | - 1959 - Peter Karlson, german | | | biochemist, and Martin | | | Lüscher, swiss entomologist, | | | coined the term \"pheromone\" | | | (Greek word, which means | | | \"carrier of excitement\"). | | | | | | - 1961 - Colin G. Butler at the | | | Rothamsted Experimental | | | Station in London used a | | | behavioral assay (mandibular | | | gland secretion assay) to | | | identify a pheromone that | | | regulates the physiological | | | development of an insect, | | | specifically the honey bee. | | | Through this experiment, he | | | identified a pheromone | | | produced by the queen bee | | | that would suppress the | | | rearing of queens and halt | | | the development of the worker | | | bees\' ovaries. | | | | | | - Dietrich Schneider, an expert | | | in electrophysiology who | | | developed an electrical means | | | of detecting pheromones. He | | | proved that the \"sniffer\" | | | of the pheromones was the | | | antennae of male moth. He | | | removed the male silkworm | | | antennae and then bathed it | | | with a saline solution to | | | keep the freshness of the | | | antennal cell. He then gave | | | the antenna a bombykol and | | | was thrilled about electrical | | | activity due to the exposure | | | to the pheromone. He | | | eventually named the | | | invention as an | | | electroantennogram (EAG). | | | | | | - In 1970, various researchers | | | are working to identify the | | | pheromones from the codling | | | moth (essential insect pests | | | of apple). | | | | | | - In 1971, Wendell Roelofs from | | | Cornell University identify | | | the pheromones following a | | | new shortcut. Roelofs and his | | | colleagues use gas | | | chromatography to separate | | | extracts into fractions. Each | | | fraction was tested with | | | Electroantenogram to which | | | the highest peak may contain | | | the pheromones. | | | | | | - Conventionally, spectral | | | analysis was used to isolate | | | the pheromone in the | | | fraction, a prolonged and | | | labor-intensive process. They | | | speed-up the process by | | | testing the library of all | | | mono-unsaturated compounds | | | that are related to the | | | pheromones. · Using the | | | antennae of male codling | | | moth, testing each compound | | | until a more significant EAG | | | response found a double bond | | | from two compounds. The | | | result had led to the | | | identification of the | | | pheromones to contain double | | | bonds in one compound. | | | | | | 1. **Social pheromones** -- use | | | by queen bees and termites to | | | regulate the development of | | | the worker bees\'/termites\' | | | ovaries, rendering them | | | sterile. | | | | | | Figure 66. Queen bee produces a | | | social pheromone. Photo courtesy: | | | Pixabay photo. Date accessed: | | | July 26, 2020. Taken from: | | | [[https://cutt.ly/tsj1Xci]{.under | | | line}](https://cutt.ly/tsj1Xci) | | | | | | **2. Alarm pheromones** -- In | | | honey bees, they use alarm | | | pheromones to recruit nestmates | | | to sting and pursue intruders. | | | | | | - In aphids, give off alarm | | | pheromones that urge | | | neighboring aphids to flee | | | from nearby predators | | | | | | Figure 67. The cornicles of aphid | | | (tubular structure at the back) | | | secreting a mixture of hemolymph, | | | lipids, and an alarm pheromone | | | called E-β-farnesene. Photo | | | courtesy: Wikimedia. Date | | | accessed: July 26, 2020. Taken | | | from | | | [[https://cutt.ly/msj4Mqc]{.under | | | line}](https://cutt.ly/msj4Mqc) | | | | | | **3. Trail-marking pheromones** - | | | are used by ants to inform other | | | individuals of their species the | | | location of a potentially good | | | food source. All individuals must | | | deposit a pheromone to maintain | | | the trail. | | | | | | Figure 68. A diagrammatical | | | representation of food-finding by | | | ants and the formation of a | | | single trail by them. Photo | | | courtesy: Mute-SourceForge. Date | | | accessed: July 26, 2020. Taken | | | from: | | | [[https://cutt.ly/Wsj8iaw]{.under | | | line}](https://cutt.ly/Wsj8iaw) | | | | | | 4.    **Repelling pheromones** -- | | | used by some flies, moths, and | | | beetles when laying their eggs to | | | repel competing species or other | | | individuals of the same species, | | | thereby protecting their progeny | | | from competition for resources. | | | | | | 5\. **Aggregation pheromones** | | | -- used by both male and female | | | bark beetles (specifically, Ips | | | confusus) to colonize specific | | | pine trees en masse. | | | | | | 6\. **Aphrodisiac pheromones** | | | -- used by some male moths to | | | entice females to mate with | | | them. | | | | | | 7\. **Sex attractant | | | pheromones** are used by | | | insects (usually female) to | | | attract the opposite sex of the | | | same species for mating. | | | | | | +--------------+--------------+ | | | | INSECT PESTS | PHEROMONES | | | | +==============+==============+ | | | | *Helicoverpa | (Z)-11-hexad | | | | | armigera* | ecenal | | | | | | and | | | | | | ((Z)-9-hexad | | | | | | ecenal | | | | | | (97:3) | | | | +--------------+--------------+ | | | | *Pectinophor | cis cis and | | | | | a | cis trans | | | | | gossypiella* | isomers of | | | | | | hexa | | | | | | decadienyl | | | | | | acetate and | | | | | | (EE)-7,11-he | | | | | | xadecadiene, | | | | | | 1-ol-acetate | | | | | | (1:1) | | | | +--------------+--------------+ | | | | *Spodoptera | (Z,E) 9,11 | | | | | litura* | tetra | | | | | | decadienyl | | | | | | acetate and | | | | | | | | | | | | (Z,E) 9, 12 | | | | | | tetra | | | | | | decadienyl | | | | | | acetate | | | | | | (10:1) | | | | +--------------+--------------+ | | | | *Scirpophaga | (Z)-9-hexade | | | | | incertulas* | cenal | | | | | | and | | | | | | | | | | | | (Z)-11-hexad | | | | | | ecenal | | | | | | (1:3) | | | | +--------------+--------------+ | | | | *Sesamia | (Z)-11-hexad | | | | | inferens* | ecenal | | | | | | acetate | | | | | | | | | | | | (Z)-11-hexad | | | | | | ecenal-1-ol | | | | | | | | | | | | (Z)-11-hexad | | | | | | ecenal | | | | | | (4:1:0.1) | | | | +--------------+--------------+ | | | | *Sitophilus | (R,5)-methyl | | | | | oryzae* | e-5-hydroxy | | | | | | 3-heptanone | | | | +--------------+--------------+ | | | | *Rhyzopertha | 1-methylbuty | | | | | dominica* | l(e)-2methyl | | | | | | -2-pentenoat | | | | | | e1-methyl | | | | | | butyl | | | | | | €-2,4-dimeth | | | | | | yl-22-penten | | | | | | oate | | | | +--------------+--------------+ | | | | | | 1. Monitoring of insect pests | | | | | | 2. Control of pest by mass | | | trapping or male annihilation | | | technique | | | | | | 3. Control of pest by mating | | | disruption | | | | | | 4. Control by lure and kill | | | method | | | | | | Table 1. Use of pheromones from | | | different countries to monitor | | | insect pest population | | | | | | INSECT PESTS | | | COUNTRY | | | ------------------------------- | | | - ------------------------------- | | | ------------ | | | Pea moth | | | UK, Europe | | | Diamond back moth | | | USA, Europe, India, Southeast A | | | sia | | | Pink bollworm | | | USA, Peru, Israel, Egypt, India | | | , pakistan | | | Tobacco budworm | | | USA | | | Corn earworm | | | USA | | | American bollworm | | | India, Egypt, Pakistan, Austral | | | ia | | | Spiny bollworm | | | India, Egypt, Pakistan | | | Spotted bollworm | | | India, Pakistan | | | Tobacco caterpillar | | | India, Japan | | | Boll weevil | | | USA | | | Sweet Potato weevil | | | USA | | | Fruit fly | | | India | | | Eggplant fruit and shoot borer | | | India | | | Sugarcane early shoot borer | | | India | | | Rice yellow stem borer | | | India, Pakistan, Bangladesh | | | | | | INSECT PESTS COUNTRY | | | -------------------- ---------- | | | ----- | | | Spruce bark beetle Scandinavi | | | a | | | Fir beetle USA, Canad | | | a | | | Boll Weevil USA | | | Palm weevil Costa Rica | | | Japanese beetle USA | | | Olive fly Spain, Gre | | | ece | | | Housefly Worldwide | | | Cockroaches Worldwide | | | Gypsy moth USA, Canad | | | a | | | Cocoa pod borer Malaysia | | | Beet Armyworm Japan | | | Yellow Stem borer India | | | | | | INSECT PESTS CO | | | UNTRY | | | ---------------------------- -- | |