Ent Final Study Guide PDF

Lecture 16: Insect Maintenance and Movement (Part II) Key Concepts 1. Excretion: a. Form of nitrogenous waste: Uric acid (minimizes water loss). b. Organs involved: Malpighian tubules filter hemolymph, and the hindgut processes and excretes waste. 2. Tracheal Sy...

Lecture 16: Insect Maintenance and Movement (Part II) Key Concepts 1. Excretion: a. Form of nitrogenous waste: Uric acid (minimizes water loss). b. Organs involved: Malpighian tubules filter hemolymph, and the hindgut processes and excretes waste. 2. Tracheal System: a. Anatomy: Spiracles (entry points), tracheae (tubes), tracheoles (direct to tissues). b. Function: Oxygen diffusion to cells. c. Limitation: Diffusion inefficiency restricts insect size. 3. Aquatic Insect Respiration: a. Open systems: Snorkel-like siphons (mosquito larvae). b. Closed systems: Gills or cuticular respiration. c. Transportable adaptations: Air bubbles or plastrons (e.g., diving beetles). 4. Circulatory System: a. Hemolymph: Water, ions, nutrients, and immune cells. b. Dorsal blood vessel: Divided into the heart (posterior) and aorta (anterior). c. Blood flow: Open circulation with hemolymph flowing from the heart to the body cavity. Practice Questions 1. Why is uric acid advantageous for insect excretion? 2. What limits the size of insects based on their respiratory system? 3. Compare stationary and transportable oxygen adaptations in aquatic insects. Lecture 17: Insect Nervous System (Parts I & II) Key Concepts 1. Subsystems: a. Central, peripheral, stomatogastric, sensory.  2. Ganglia and Functions: a. Brain: Vision, coordination. b. Subesophageal ganglion: Controls mouthparts. c. Thoracic ganglia: Limb movement. 3. Mechanoreceptors: a. Proprioceptors (e.g., hair plates for limb positioning). b. Tympanum (e.g., hearing in moths). 4. Eyes: a. Ommatidia (compound eyes, for mosaic vision). b. Ocelli (light detection in adults) vs. stemmata (larval eyes). 5. Chemical Communication: a. Pheromones: Intraspecific communication. b. Allelochemicals: Allomones (benefit emitter), kairomones (benefit receiver), synomones (mutual benefit). Practice Questions 1. Explain how the insect central nervous system coordinates movement. 2. Define and give examples of mechanoreceptors in insects. 3. Compare ocelli and compound eyes in terms of structure and function. 4. What are kairomones, and how do they function in insect interactions? Lecture 18: Social Insects Key Concepts 1. Sociality Levels: a. Solitary, subsocial, eusocial (cooperative care, division of labor, overlapping generations). 2. Caste System: a. Honey bees: Workers (female, non-reproductive), drones (male), queens (reproductive females). b. Royal jelly: Determines queen development. 3. Ant Behaviors: a. Slave-making ants, foraging trails, army ants’ nomadic behaviors. 4. Pollination: a. Process involving nectar, pollen, and reproductive organs of flowers.  b. Bee bread: Fermented pollen for larvae. Practice Questions 1. What defines eusociality, and which insects exhibit it? 2. How does royal jelly influence caste differentiation in honey bees? 3. Describe the roles of worker ants in their colonies. Lecture 19 & 20: Insect Pests and Pest Management Key Concepts 1. Economic Threshold (ET) and Economic Injury Level (EIL): a. ET: Pest population level requiring control to prevent EIL. b. EIL: Level where pest damage equals the cost of control. 2. Insecticides: a. Categories: Inorganic, microbial, botanical, synthetic. b. Methods of entry: Contact, ingestion, systemic absorption. 3. Integrated Pest Management (IPM): a. Combines cultural, biological, mechanical, and chemical controls. 4. Resistance Development: a. Mechanisms: Behavioral (avoiding toxins), metabolic (detoxifying chemicals), genetic (mutations). Practice Questions 1. Differentiate between ET and EIL in pest management decisions. 2. What are three ways insects develop resistance to insecticides? 3. Provide examples of cultural, biological, and chemical controls used in IPM. General Practice Questions 1. What limits the size of terrestrial insects based on their respiratory system? 2. How do pheromones differ from allelochemicals in insect communication? 3. What traits define eusocial insects, and what examples can you provide? 4. Why was Rachel Carson significant in the field of pest management?  5. What are the differences between a high EIL and a low EIL scenario in agriculture? Practice Final Exam: Insect Biology and Management Section 1: Short Answer (2 points each) 1. In what form do insects excrete nitrogenous waste, and why is this adaptation advantageous? 2. Describe the structure and function of the Malpighian tubules in insect excretion. 3. Explain how the tracheal system limits the maximum size of insects. 4. Differentiate between open and closed respiratory systems in aquatic insects with examples. 5. What is the dorsal blood vessel, and what are its main components? 6. Describe the role of pheromones in insect communication. Provide an example of their use in pest management. 7. What are the three traits that define eusocial insects? 8. Explain how insects use chemoreceptors to detect environmental cues. 9. Define the Economic Injury Level (EIL) and explain its significance in pest management. 10. What is the role of cultural controls in Integrated Pest Management (IPM)? Provide an example. Section 2: Matching (1 point each) Column A Column B 1. Tympanum | A. Nutrient transport and immune response 2. Mosaic vision | B. Hearing in insects 3. Royal jelly | C. Fixed action pattern 4. Hemolymph | D. Compound eye function 5. Kairomone | E. Queen differentiation 6. Sterile insect release | F. Benefits receiver but harms emitter 7. Pollination | G. Symbiotic mutual benefit 8. Bee bread | H. Fermented pollen 9. Rachel Carson | I. Silent Spring author 10. Proprioceptor | J. Limb positioning Section 3: Multiple Choice (2 points each) 1. Which organ allows insects to regulate water and excrete waste? A. Spiracles B. Malpighian tubules C. Tracheoles D. Hemolymph 2. What limits the effectiveness of the insect tracheal system? A. Low oxygen concentration in the air B. Its reliance on diffusion C. Lack of hemoglobin D. High metabolic rates 3. Which of the following is an example of a microbial insecticide? A. Bacillus thuringiensis (Bt) B. Pyrethrin C. DDT D. Neonicotinoids 4. What is the primary function of the insect subesophageal ganglion? A. Coordinating wing movements B. Controlling mouthparts C. Detecting pheromones D. Generating sound  5. What are ocelli used for? A. High-resolution vision B. Detecting light intensity C. Tracking prey movement D. Enhancing color vision 6. Which type of pheromone is used by insects for mating? A. Kairomone B. Allomone C. Sex pheromone D. Synomone 7. Which condition would result in a high Economic Injury Level (EIL)? A. A highly valuable crop with minor pest presence B. A low-value crop with high pest density C. High pest density in a high-value crop D. Low pest density in a low-value crop 8. What distinguishes subsocial insects from eusocial insects? A. Subsocial insects have castes. B. Subsocial insects lack cooperative brood care. C. Subsocial insects exhibit overlapping generations. D. Subsocial insects build complex nests. Section 4: Diagrams (5 points each) 1. Draw and label the major structures of the insect tracheal system, including spiracles, tracheae, and tracheoles. 2. Sketch a cross-section of a single ommatidium and label its components. 3. Create a graph showing a hydrograph for a restored wetland compared to its pre- restoration state. Annotate the graph to explain changes in peak flow and lag time. Section 5: Essay Questions (10 points each) 1. Insect Circulatory System: Describe the structure and function of the insect circulatory system. How does it differ from the human circulatory system? 2. Integrated Pest Management (IPM): Define IPM and outline its key components. Provide an example of how cultural, biological, and chemical controls can be integrated to manage a specific pest. 3. Ecosystem Services of Insects: Discuss the roles of insects in pollination, nutrient cycling, and pest control. What are the implications of declining insect populations on these ecosystem services? 4. Insecticide Resistance: Explain how insects develop resistance to insecticides over time. What strategies can be employed to delay resistance? Section 1: Short Answer 1. How do insects acquire oxygen in aquatic environments? Differentiate between open and closed systems. 2. Explain the role of hair plates as proprioreceptors in insects.  3. What is the significance of the subesophageal ganglion in insect nervous systems? 4. Describe the process of pseudocopulation and its ecological significance. 5. What are the functions of insect hemolymph? How is it different from human blood? 6. Define secondary pests and pest resurgence. Provide an example of each. 7. Describe the general anatomy and function of the dorsal vessel in insects. 8. What are the main features of a honeybee waggle dance, and how does it communicate the location of a food source? Section 2: Fill in the Blank 1. Insects excrete nitrogenous waste in the form of _________. 2. The tracheal system limits insect size because it relies on _________ for gas exchange. 3. _________ is the term for insect resistance to a pest control method after repeated exposure. 4. _________ pheromones are used by males to locate females for mating. 5. The three main traits of eusociality are cooperative brood care, reproductive division of labor, and _________. Section 3: Multiple Choice 1. Which of the following is not a function of the insect circulatory system? A. Transport of oxygen B. Distribution of nutrients C. Immune response D. Waste removal 2. What type of insect pest control involves the release of sterilized individuals to reduce reproduction? A. Cultural control B. Biological control C. Genetic control D. Chemical control 3. What adaptation helps insects conserve water during excretion? A. Spiracles B. Malpighian tubules C. Tracheae D. Hemolymph 4. The mosaic theory of insect vision suggests that: A. Insects see a single, focused image. B. Each ommatidium contributes a part of a composite image. C. Simple eyes detect light intensity but not direction. D. Insect vision is similar to human vision. 5. Which type of insect eye is typically found in larval stages? A. Compound eyes B. Ocelli C. Stemmata D. Proprioreceptors Section 4: Matching Column A Column B 1. Mass trapping | A. Control using parasitoids 2. Kairomone | B. Benefits the receiver, harms the emitter 3. Allomone | C. Benefits the emitter, neutral for receiver 4. Synomone | D. Mutual benefit for emitter and receiver  5. IPM | E. Integrated Pest Management Section 5: Essays 1. Insect Movement and Gas Exchange: Describe how the tracheal system allows gas exchange in insects. How does this system impact their activity levels and habitat choices? 2. Biological Control Methods: Compare and contrast the three main types of biological control: classical, augmentative, and conservation. Provide specific examples of each. 3. Social Insects and Ecosystem Roles: Discuss how social insects contribute to ecosystem services such as pollination and decomposition. How might declines in social insect populations affect ecosystems? 4. Rachel Carson’s Impact on Pest Management: Summarize the contributions of Rachel Carson and her book Silent Spring to the development of modern pest management practices. How did her work influence IPM? Additional Challenge Questions 1. Explain how insecticides are classified based on their routes of entry and modes of action. Provide an example of each classification. 2. Why are aquatic insects with closed respiratory systems often found in low-oxygen environments? 3. How do paper wasps construct their nests, and how does this process change seasonally? 4. Describe the process of learning in insects. Give an example of an insect species capable of learning. 5. What strategies can farmers use to delay the development of insecticide resistance in pests? ANSWERS Here are the answers for the practice final exam questions: Section 1: Short Answer 1. How do insects acquire oxygen in aquatic environments? Differentiate between open and closed systems. a. Insects acquire oxygen through either open or closed respiratory systems. i. Open system: Oxygen is absorbed directly from the water through gills or spiracles that are exposed to water. ii. Closed system: Aquatic insects may carry a bubble of air with them, or use a structure that can trap air at the surface, allowing for continuous gas exchange. 2. Explain the role of hair plates as proprioreceptors in insects. a. Hair plates are sensory structures that detect mechanical changes in the environment, such as touch, vibration, or pressure. They help insects perceive movement, position, and orientation. 3. What is the significance of the subesophageal ganglion in insect nervous systems? a. The subesophageal ganglion controls functions related to the mouthparts, feeding, and salivation. It plays an important role in coordinating movements related to ingestion and digestion. 4. Describe the process of pseudocopulation and its ecological significance. a. Pseudocopulation occurs when one insect mimics mating behavior to either obtain food or protect itself from predation (e.g., certain orchids mimicking female insects to attract males for pollination). It shows the relationship between organisms and coevolution. 5. What are the functions of insect hemolymph? How is it different from human blood? a. Hemolymph functions in nutrient transport, immune response, and waste removal. It is different from human blood in that it does not carry oxygen  (since insects rely on the tracheal system for respiration) and it is not contained in vessels like blood. 6. Define secondary pests and pest resurgence. Provide an example of each. a. Secondary pests: Pests that become problematic after a primary pest is controlled, often due to the loss of natural predators (e.g., aphids after pesticide use for another pest). b. Pest resurgence: The rapid reappearance of a pest population after control measures have been applied (e.g., pesticide resistance or ineffective control methods). 7. Describe the general anatomy and function of the dorsal vessel in insects. a. The dorsal vessel is the insect’s heart-like structure that moves hemolymph (fluid) throughout the body. It consists of a heart at the posterior end and aorta at the anterior end, and helps circulate the hemolymph. 8. What are the main features of a honeybee waggle dance, and how does it communicate the location of a food source? a. The waggle dance consists of a figure-eight pattern where the bee waggles its body during the straight portion to indicate direction and distance to a food source relative to the sun. Section 2: Fill in the Blank 1. Insects excrete nitrogenous waste in the form of uric acid. 2. The tracheal system limits insect size because it relies on diffusion for gas exchange. 3. Insecticide resistance is the term for insect resistance to a pest control method after repeated exposure. 4. Sex pheromones are used by males to locate females for mating. 5. The three main traits of eusociality are cooperative brood care, reproductive division of labor, and overlapping generations. Section 3: Multiple Choice 1. Which of the following is not a function of the insect circulatory system? A. Transport of oxygen  a. The circulatory system does not transport oxygen in insects. Oxygen is carried through the tracheal system. 2. What type of insect pest control involves the release of sterilized individuals to reduce reproduction? C. Genetic control a. This refers to the release of sterilized insects to reduce reproduction, a form of genetic control. 3. What adaptation helps insects conserve water during excretion? B. Malpighian tubules a. Malpighian tubules help insects conserve water by excreting nitrogenous waste as uric acid, which conserves water. 4. The mosaic theory of insect vision suggests that: B. Each ommatidium contributes a part of a composite image. a. The mosaic theory suggests that each ommatidium (a single unit in the compound eye) contributes a small part to the full image seen by the insect. 5. Which type of insect eye is typically found in larval stages? C. Stemmata a. Stemmata are simple eyes found in larvae, which help them detect light and dark but not detailed images like compound eyes. Section 4: Matching Column A Column B 1. Mass trapping | E. Integrated Pest Management (IPM) 2. Kairomone | B. Benefits the receiver, harms the emitter 3. Allomone | C. Benefits the emitter, neutral for receiver 4. Synomone | D. Mutual benefit for emitter and receiver 5. IPM | E. Integrated Pest Management Section 5: Essays 1. Insect Movement and Gas Exchange: a. Insects rely on the tracheal system for gas exchange, which is made up of a network of tubes that carry air directly to the tissues. The system limits insect size because as insects grow larger, it becomes harder to deliver oxygen effectively to all tissues. Larger insects may struggle with this system as diffusion alone becomes insufficient for gas exchange, which is why insect size is generally constrained. 2. Biological Control Methods: a. Classical biological control involves introducing natural enemies from the pest’s native habitat. For example, introducing parasitoid wasps to control pests. b. Augmentative biological control involves supplementing the population of natural enemies in the area to enhance pest control, like releasing more predatory beetles. c. Conservation biological control focuses on protecting or enhancing the effectiveness of natural enemies already present. For instance, planting diverse vegetation to support predators of pests. 3. Social Insects and Ecosystem Roles: a. Social insects such as bees and ants provide essential ecosystem services like pollination, soil aeration, and decomposition. Declines in these populations can negatively impact agricultural yields, biodiversity, and ecosystem health. 4. Rachel Carson’s Impact on Pest Management: a. Rachel Carson’s Silent Spring challenged the indiscriminate use of chemical pesticides, particularly DDT, and highlighted their environmental consequences. Her work was instrumental in the development of Integrated Pest Management (IPM), which promotes using a combination of biological, cultural, mechanical, and chemical methods to control pests in an environmentally sustainable way. Additional Challenge Questions 1. Explain how insecticides are classified based on their routes of entry and modes of action. Provide an example of each classification.  a. Routes of entry: Insecticides can enter the insect through ingestion, inhalation, or direct contact. i. Example: Contact insecticides (e.g., pyrethroids) affect insects when they come into contact with the chemical. b. Modes of action: Insecticides may affect nervous system function (e.g., neonicotinoids), digestion (e.g., growth regulators), or respiration (e.g., organophosphates). 2. Why are aquatic insects with closed respiratory systems often found in low- oxygen environments? a. Aquatic insects with closed respiratory systems can trap air and use it over time, allowing them to survive in low-oxygen environments. These insects carry an air bubble or use other adaptations like gills to extract oxygen from the water. 3. How do paper wasps construct their nests, and how does this process change seasonally? a. Paper wasps create nests by chewing wood fibers mixed with saliva to form a paper-like substance. Their nests are typically started by a single queen in spring, and they expand in size as more workers emerge. In fall, nests may be abandoned or die off as new queens are produced. 4. Describe the process of learning in insects. Give an example of an insect species capable of learning. a. Insects can learn through classical conditioning (associating a neutral stimulus with a significant one) and operant conditioning (learning through rewards or punishments). For example, honeybees can learn to associate a specific flower color with nectar. 5. What strategies can farmers use to delay the development of insecticide resistance in pests? a. Strategies include rotating insecticides with different modes of action, using insecticides selectively, integrating non-chemical control methods, and using IPM to manage pest populations sustainably. Lecture 16: 1. Insects Excrete Nitrogenous Waste in What Form? Insects excrete nitrogenous waste primarily in the form of uric acid (often in the form of uric acid salts). This form of waste is relatively insoluble in water, which makes it an efficient way for insects to conserve water. 2. Brief Description of Insect Excretion and Important Organs Involved Excretory Organs: Insects excrete waste through the Malpighian tubules and rectum. o Malpighian Tubules: These are long, tube-like structures that float freely in the insect’s body cavity. They filter waste from the hemolymph (the insect’s blood). The nitrogenous waste is mainly uric acid salts, which are transported into the tubules by diffusion and active transport. o Rectum: After the waste is filtered by the Malpighian tubules, it moves into the hindgut and rectum, where water is reabsorbed. This process produces dry feces or frass. Excretion Process: o Nitrogenous waste from hemolymph enters the Malpighian tubules. o Waste is concentrated and transported to the hindgut. o Water, sugars, salts, and amino acids are reabsorbed in the rectum. o The remaining dry waste (frass) is excreted. 3. Anatomy of the Tracheal System and How Insects Get Air Inside Tracheal System: The tracheal system is a network of air tubes that transport oxygen directly to the insect's tissues. o Spiracles: Small openings on the insect’s body that allow air to enter the tracheal system. o Tracheae: Tubes that carry air from the spiracles to smaller branches. o Tracheoles: Tiny, finer tubes that deliver oxygen directly to individual cells. How Air Enters: Air enters through spiracles, passes through the tracheae and tracheoles, and delivers oxygen directly to the cells, bypassing the circulatory system. 4. How Does the Tracheal System Limit Insect Size? The tracheal system limits insect size because it relies on passive diffusion to move oxygen through the system. As insects get larger, the distance oxygen must travel increases, and diffusion becomes less efficient. This makes it harder for large insects to deliver enough oxygen to their tissues without a more advanced circulatory system or external respiratory structures, which insects lack. 5. Different Ways Aquatic Insects Acquire Oxygen Open vs. Closed Systems: o Open System: Involves direct exchange of gases with the surrounding water (e.g., aquatic insects that have gills). o Closed System: Involves internal gas storage, where the insect carries air in specialized structures like bubbles or tracheal tubes. Stationary vs. Transportable Systems: o Stationary: Some insects (like certain larvae) rely on fixed gas-exchange structures like gills that are stationary in water. o Transportable: Some insects (like diving beetles) carry a bubble of air that they can transport to different depths for respiration. Temporary vs. Permanent Transportable Systems: o Temporary Transportable: Insects like water beetles use air bubbles for short periods and must return to the surface to replenish air. o Permanent Transportable: Some aquatic insects carry air with them in specialized sacs that allow for more extended periods of underwater respiration. 6. General Pattern of Blood Flow in Insects Hemolymph: Insects have an open circulatory system, meaning the blood (hemolymph) is not contained in blood vessels but flows freely in the body cavity (hemocoel). Flow Direction: o The dorsal heart pumps hemolymph from the posterior to the anterior part of the insect.  o The hemolymph moves into the body cavity and bathes the tissues before returning to the heart. o The heart pumps blood in a forward direction, and then the hemolymph returns to the body cavity through pores. 7. What is the Dorsal Blood Vessel? Its Parts? Where Is It Located? The dorsal blood vessel is the primary structure in the insect circulatory system, acting as the heart. o Parts: ▪ Heart: The muscular part of the dorsal vessel that pumps hemolymph. ▪ Aorta: The front part of the dorsal blood vessel that extends towards the head and pumps hemolymph into the head and thorax regions. ▪ Ostia: Small openings along the dorsal vessel that allow hemolymph to flow into the vessel. Location: The dorsal blood vessel runs along the back (dorsal side) of the insect’s body, from the posterior end to the anterior end. 8. What Makes Up Insect Hemolymph? What Are the Major Functions of the Insect Circulatory System? Hemolymph Composition: o Plasma: A watery substance containing nutrients, hormones, salts, and waste products. o Cells: Including hemocytes, which are involved in immune responses, wound healing, and coagulation. Functions of Insect Circulatory System: o Transport of Nutrients: Hemolymph delivers nutrients to tissues. o Transport of Hormones: Carries hormones to regulate processes like growth and reproduction. o Immune Function: Hemolymph contains hemocytes that help fight infections and heal wounds. o Waste Removal: Carries metabolic waste products from tissues to excretory organs like the Malpighian tubules.  o Heat Regulation: Hemolymph helps maintain temperature balance by transporting heat. Lecture 17: 1. Four Major Subsystems of the Nervous System The nervous system of insects is divided into four major subsystems: Central Nervous System (CNS): Includes the brain and ventral nerve cord, responsible for processing and integrating sensory information and controlling movement. Peripheral Nervous System (PNS): Includes sensory and motor neurons that connect the CNS to the body, carrying signals to and from various organs. Autonomic Nervous System: Controls involuntary functions, like digestion and heart rate, often regulated by ganglia. Enteric Nervous System: Regulates the gut and digestive processes, independent of the brain. 2. Ganglia of the Insect Central Nervous System (CNS) Brain: Located in the head, the brain is divided into several lobes (protocerebrum, deutocerebrum, tritocerebrum) and controls sensory processing, behavior, and higher functions. Subesophageal Ganglion: Controls the mouthparts, salivary glands, and parts of the thoracic and abdominal regions. Thoracic Ganglia: Responsible for controlling movement and sensory inputs from the legs and wings. Abdominal Ganglia: Control movements of the abdomen, including the reproductive organs and digestive system. These ganglia are connected to various organs, and their nerves are involved in functions such as sensory perception (e.g., from antennae, legs) and motor control (e.g., muscle movement). 3. Ommatidium Structure The ommatidium is the basic functional unit of the compound eye. On a cross-section of a single ommatidium, you can label: Cornea: Transparent outer structure that focuses light. Cone Cells: Cells that direct light towards the photoreceptor cells. Rhabdom: The light-sensitive structure formed by the photoreceptor cells. Retinula Cells: These contain pigments and are sensitive to light, transmitting visual information to the brain. Pigment Cells: Cells that prevent light from scattering between ommatidia. 4. Mosaic Theory of Insect Vision The Mosaic Theory of insect vision suggests that each ommatidium in a compound eye contributes a small portion (or pixel) of the entire visual field. Each ommatidium is responsible for detecting light from a specific direction, and the brain integrates the information from all these small "pixels" to create a mosaic-like image. This allows insects to have a broad field of vision, although with lower resolution compared to vertebrate eyes. 5. Mechanoreceptors and Functions Mechanoreceptors detect mechanical changes like pressure, vibration, and touch. Key types include: Hair Plates: These are proprioceptors, specialized mechanoreceptors found on the body surface, particularly on the legs, and help detect body position, movement, and tension. Chordotonal Organs: Detect vibrations and sounds, often found in the legs and antennae. Campaniform Sensilla: Detect strain and stress on the exoskeleton, providing feedback about mechanical deformations. Tactile Hairs (Setae): These are used for touch sensitivity, found in various parts of the body, like antennae, legs, and the head. 6. Types of Insect Simple Eyes (Ocelli vs. Stemmata) Ocelli: Simple eyes that are typically found on the top of the head (usually three) in adult insects. They detect light intensity and help with orientation, balancing, and flight stability. o Example: Found in many adult insects, including bees, flies, and grasshoppers. Stemmata: Simple eyes found mainly in the larval stages of holometabolous insects. They have a lower resolution than compound eyes and are used mainly to detect light and dark, helping larvae with navigation. o Example: Found in the larvae of moths, beetles, and butterflies. 7. Chemoreceptors and Their Locations Chemoreceptors allow insects to detect chemical signals such as pheromones, odors, and taste. They are found in various places on the insect body: Antennae: The primary location for olfactory chemoreceptors (smell), used to detect pheromones and environmental odors. Maxillary Palps: Have chemoreceptors to detect food-related chemicals. Tarsi (on legs): Chemoreceptors on the legs help detect food and other chemical cues when the insect walks on surfaces. Labial Palps: Similar to maxillary palps, they assist in detecting chemicals in food. Cuticle: Some chemoreceptors are embedded in the cuticle, allowing the insect to "taste" or sense chemicals directly from surfaces. Summary: The nervous system in insects is divided into four subsystems with specific roles, with ganglia in the brain and other areas controlling motor and sensory functions. The ommatidium is the basic unit of the compound eye, forming a mosaic of visual information. The Mosaic Theory explains how each ommatidium contributes a small part to the insect's overall vision.  Mechanoreceptors (e.g., hair plates) and chemoreceptors (e.g., on antennae) detect physical and chemical stimuli to help insects navigate and interact with their environment. Ocelli and stemata are types of simple eyes, found in different insect life stages. Lecture 17 II: 1. Different Types of Taxis and Insect Examples Taxis is a directional response to a stimulus, and it can be classified into several types: Positive Taxis: Movement toward the stimulus. o Example: Moths exhibit positive phototaxis by flying toward light sources at night. Negative Taxis: Movement away from the stimulus. o Example: Cockroaches exhibit negative phototaxis, avoiding light and moving into dark spaces. Chemotaxis: Movement in response to chemical stimuli. o Example: Ants use chemotaxis to follow pheromone trails to food sources. Gravitaxis: Movement in response to gravity. o Example: Beetle larvae exhibit positive gravitaxis by moving downward into the soil. Thigmotaxis: Movement in response to touch. o Example: Spiders move in response to vibrations on their webs. 2. What are Pheromones and Allelochemicals? Pheromones are chemicals released by an individual to affect the behavior or physiology of another individual of the same species. o Example: Queen bee pheromones control worker bee behavior. Allelochemicals are chemicals produced by one species that affect the behavior of another species, and they can be further classified into: o Allomones: Beneficial to the sender but harmful or neutral to the receiver. o Kairomones: Beneficial to the receiver but harmful to the sender. o Synomones: Beneficial to both sender and receiver. 3. What are Sex Pheromones? How Do They Function? How Do Males Locate Females? Sex Pheromones are chemicals released by an individual (usually females) to attract mates. o Function: They signal mating readiness and attract males over long distances. o Example: Moths release sex pheromones to attract males, and males use their antennae to detect the pheromone and locate the female. 4. When Are Visual Communicators Most Active? Visual communication is most active during daylight when insects rely on sight to communicate. Example: Dragonflies use visual signals to communicate with other dragonflies during mating seasons. Example: Fireflies use bioluminescent signals to attract mates at night. 5. What is a Tymbal? A tymbal is a specialized sound-producing organ found in certain insects, particularly cicadas and crickets. Function: It produces sound by rapidly vibrating a membrane, typically used in mating calls. o Example: Cicadas use their tymbals to produce loud, species-specific calls to attract mates. 6. Define Allomone, Synomone, Kairomone Allomone: A chemical released by one species that benefits the sender but may be neutral or harmful to the receiver. o Example: A plant releasing a chemical to repel herbivores. Synomone: A chemical that benefits both the sender and the receiver.  o Example: Flowers releasing scents that attract pollinators. Kairomone: A chemical that benefits the receiver (often a predator or parasite) but is harmful to the sender. o Example: Pheromones from prey species that attract predators like spiders or parasitic wasps. 7. Can Insects Learn? Cite Some Examples Yes, insects can learn through experience, and several examples include: Honeybees can learn to associate specific colors or shapes with food rewards. Fruit flies have shown associative learning in response to odor and light, allowing them to associate smells with either food or danger. Ants can learn routes and locations based on previous experiences, improving their foraging efficiency. 8. Examples of Different Fixed Action Patterns (FAPs) Fixed Action Patterns (FAPs) are instinctive, stereotyped behaviors triggered by specific stimuli: Egg-Retrieving Behavior in Geese: When an egg rolls out of the nest, the mother goose will retrieve it with a specific motion, even if the egg is replaced by an object. Male Stickleback Fish Aggression: Male fish display aggressive behavior when they see a red belly, even if the stimulus is not a real rival. 9. How Do Lightning Bugs Communicate? Lightning bugs (fireflies) communicate using bioluminescence to attract mates. o Mating Calls: Females emit specific patterns of light, and males respond with complementary flashes. o Example: Photinus fireflies flash in a species-specific pattern to attract females, and the females respond with a similar flash. 10. How Do Cicadas Communicate? Cicadas communicate through sound produced by their tymbals. o Mating Calls: Males produce loud, rhythmic calls to attract females. o Sound Production: Cicadas use their tymbals (specialized sound-producing organs) to create sound, which varies by species. 11. How Do Honeybees Locate Food Sources Near and Far from the Colony? Near the Colony: Honeybees use the round dance to communicate the presence of food within 60 feet of the hive. The round dance communicates distance but not direction. Far from the Colony: Honeybees perform the waggle dance for food sources located more than 50 feet from the hive. The duration of the waggle portion of the dance indicates distance, and the angle relative to vertical indicates the direction of the food source, with reference to the sun. Summary: Taxis is the directional movement in response to stimuli, and each type (e.g., phototaxis, chemotaxis) can be demonstrated with insect examples. Pheromones and allelochemicals are chemical signals used for communication, and they can benefit or harm the sender or receiver. Sex pheromones are important for mating and help males locate females through scent. Visual communication is important during the day, and tymbals produce sound for communication in species like cicadas. Insects can learn through experience, as seen in bees and fruit flies. Fixed Action Patterns (FAPs) are instinctive behaviors, such as egg-retrieving in geese and aggression in fish. Insects communicate in a variety of ways, from bioluminescence in fireflies to sound in cicadas and dance in honeybees. Lecture 18: 1. What is Royal Jelly? What Future Caste(s) Are Fed Royal Jelly? Royal Jelly is a secretion produced by worker bees that is fed to larvae. It is rich in proteins and vitamins and serves as the exclusive food for queen larvae throughout their development. o Queen Larvae: The larvae destined to become queens are fed royal jelly continuously. o Worker Larvae: Worker larvae receive royal jelly only for the first few days of life, after which they are fed a mixture of honey and pollen. 2. What is Pollination? Review the Flower Organs Involved in the Process Pollination is the process by which pollen is transferred from the male part of a flower (the anther) to the female part (the stigma) of the same or another flower, facilitating fertilization. o Male Organs: The anther produces pollen. o Female Organs: The stigma receives pollen, while the style connects it to the ovary, where fertilization occurs. o Pollination is often carried out by insects, birds, wind, or water. 3. What is Pseudocopulation? Coevolution? Pseudocopulation is a form of pollination trickery where an insect, such as a male wasp, attempts to mate with an orchid that mimics the scent and appearance of a female wasp. In doing so, the insect unknowingly picks up pollen and transfers it to another flower. Coevolution refers to the process where two species that interact closely (e.g., plants and their insect pollinators) evolve in response to each other's adaptations, often leading to highly specialized relationships. 4. What is Bee Bread? Bee Milk? Bee Bread is a fermented mixture of pollen and nectar that worker bees store in the hive as a food source for the colony. It provides essential nutrients. Bee Milk is a secretion produced by worker bees that is used to feed the queen and young larvae. It is part of the process that differentiates queen larvae from worker larvae. 5. What is Nectar? Where Is It Usually Found? Nectar is a sugary liquid produced by flowers to attract pollinators. It is usually found in the nectaries, which are specialized glands located within the flower, often near the base of the petals or in the flower's reproductive organs. 6. What is Swarming? Swarming refers to the process by which a colony of bees, particularly honeybees, splits into two or more groups. A new queen is raised, and a portion of the colony leaves to establish a new hive. o Swarming usually occurs in the spring or summer when a colony becomes overcrowded. 7. Review the Various Kinds of Ant Workers—What Are Their Tasks? Ants exhibit different types of worker castes, each with specific tasks: Minor Workers (also called small workers): Primarily perform foraging and caring for the young. Major Workers (also called soldiers): Defend the nest and protect the colony from predators. Median Workers: Typically handle tasks like nest maintenance and brood care. Specialized Workers: In some species, workers may have roles like fungus farming, tending to aphids, or even "slave-making." 8. What Percentage of Insect Species Are Considered Truly Social? Only about 2% of insect species are considered truly social, with the most prominent examples being ants, bees, termites, and wasps. 9. What Are Subsocial Insects? How Are They Different from Social or Solitary Insects? Subsocial Insects are species that exhibit some level of social organization but do not have the complex behaviors and castes seen in eusocial species. o Differences: Subsocial insects may show some care for their offspring or live in groups but lack the division of labor and permanent colony structure seen in eusocial insects. Solitary insects, like most species of butterflies or beetles, do not form groups and raise their offspring independently. 10. What Kind of Nests Do Paper Wasps Construct? Review Their Seasonality and Construction Paper Wasps build nests from paper-like material made of wood fibers and saliva. o Nest Construction: The nest starts small with a few hexagonal cells and expands as the colony grows. o Seasonality: Paper wasp colonies are typically annual, with the queen starting a new nest each year. Nests usually peak in summer and are abandoned in fall after the colony dies. 11. What is Queen Pheromone? What Is Its Function? Queen Pheromone is a chemical compound produced by the queen that is spread throughout the colony. Its function is to: o Maintain colony cohesion: The pheromone inhibits the development of worker bees into queens. o Control reproduction: It ensures that only the queen reproduces, preventing the workers from laying eggs. 12. Describe the Different Types of Honey Bee Castes Honey bee colonies have three castes: Queen: The sole fertile female responsible for egg-laying. Workers: Sterile females that forage, care for the brood, clean the hive, and perform other tasks. Drones: Males whose primary role is to mate with a queen. 13. Review the Following Ant Behaviors: Slave Making, Army Ant Behaviors Slave-making: Some ants, like Polyergus, raid the nests of other ant species and steal their pupae. When the pupae hatch, they work for the raiding ants. Army Ants: These ants do not build permanent nests. They form large, moving colonies that raid and capture prey in coordinated attacks. Army ants often move as a group, forming a living raft. 14. What Traits Define Eusociality? Eusociality is characterized by: Cooperative brood care: Workers help care for the offspring. Reproductive division of labor: A few individuals (typically a queen) reproduce while others (workers) do not. Overlapping generations: Multiple generations coexist within the colony. 15. Review the Different Kinds of Ant Nests Ant nests vary by species, but typical nest types include: Underground Nests: Most common, with intricate tunnel systems. Wooden Nests: Found in rotting wood or tree trunks (e.g., carpenter ants). Mound Nests: Created by some species like fire ants, where they build large visible mounds.  Leaf nests: Some ants, like weaver ants, build nests by linking leaves together using silk produced by their larvae. Summary: Royal Jelly is fed to queen larvae to promote their development, while worker larvae are fed it for a short time. Pollination involves transferring pollen from male to female flower parts. It is vital for reproduction. Pseudocopulation is when insects pollinate orchids by attempting to mate with flowers. Bee Bread is a fermented pollen mixture, while bee milk is a secretion for feeding larvae and queens. Nectar is a sugary liquid produced by flowers and is usually found in nectar- producing glands. Swarming is the process of colony division in honeybees, typically during the spring. Ant workers perform a variety of tasks, including foraging, brood care, and defense. Eusociality is defined by cooperative brood care, reproductive division of labor, and overlapping generations, which are seen in species like ants and bees. Lecture 19 and 20 1. EIL and ET: Decision to Control Insects EIL (Economic Injury Level): The pest population size at which the cost of pest damage equals the cost of control measures. It represents the threshold where damage is significant enough to impact profits. ET (Economic Threshold): The pest population level at which control measures should be taken to prevent the pest population from reaching the EIL. It is the point at which action should be initiated to prevent damage. o High EIL: In cases where the crop is resilient or resistant to pests, or when the damage is not significant enough to affect yield. For example, in certain crops, pests may only cause minor cosmetic damage.  o Low EIL: In situations where the crop is very susceptible, or where the value of the crop is high, meaning even minimal damage is economically significant. 2. LD50 (Lethal Dose 50) Definition: The amount of a chemical (insecticide) required to kill 50% of a population of insects. A lower LD50 indicates a more toxic substance, as it takes less of the chemical to kill half the population. 3. Host Plant Resistance Definition: The ability of a plant to resist or tolerate pest damage without significant loss in yield or function. Types of Plant Resistance: o Antibiosis: Plant produces substances harmful or toxic to the pest. o Antixenosis: Physical or chemical traits that make the plant less attractive or suitable for the pest (e.g., tough leaves, strong odors). o Tolerance: Plant can sustain some level of damage without significantly affecting growth or yield. 4. Types of Insecticides Inorganic Insecticides: o Examples: Sulfur, copper-based compounds. o Characteristics: Often target insect's respiratory system or exoskeleton. Microbial Insecticides: o Examples: Bacillus thuringiensis (Bt). o Characteristics: Bacteria that produce toxins toxic to insects when ingested. Botanical Insecticides: o Examples: Pyrethrum (from chrysanthemums). o Characteristics: Derived from plants; affect the insect’s nervous system. Synthetic Organic Insecticides: o Examples: Organophosphates (OPs), Organochlorines (OCs).  o Characteristics: Affect insect nervous system by inhibiting neurotransmission. Growth Regulators: o Examples: Juvenile hormone analogs. o Characteristics: Disrupt development and molting of insects. 5. Insecticide Classification: Routes of Entry & Modes of Action Routes of Entry: o Contact poisons: Absorbed through the exoskeleton. o Stomach poisons: Ingested through food. o Fumigants: Gases absorbed through the respiratory system. Modes of Action: o Nervous system: Disrupts nerve transmission. o Digestive system: Interferes with digestion. o Hormones: Disrupts growth or reproduction. o Muscles: Affects muscle coordination. 6. Cultural Controls Methods: o Crop rotation: Planting different crops in sequence to break pest cycles. o Intercropping: Growing different crops together to confuse pests. o Tillage practices: Turning soil to destroy pest habitats. o Timing of planting: Planting crops at times that avoid peak pest populations. o Trap crops: Growing plants that attract pests away from main crops. 7. Pheromones & Attractants Mass Trapping: Using traps baited with pheromones to capture large numbers of pests. Mating Disruption: Overwhelming the pest with high concentrations of sex pheromones to prevent mating. Genetic Manipulation (Sterile Insect Release): Releasing sterile males to mate with females, preventing reproduction and reducing pest populations. 8. IPM (Integrated Pest Management) Definition: A sustainable approach that uses multiple pest control strategies, including biological, cultural, chemical, and physical methods, to manage pest populations with minimal environmental impact. 9. Injury vs. Damage Injury: The physical harm caused by the pest (e.g., feeding on a plant). Damage: The economic loss resulting from injury (e.g., reduced crop yield or quality). 10. Significance of Rachel Carson Rachel Carson wrote Silent Spring (1962), which raised awareness about the dangers of pesticides, especially DDT, and their environmental impact. This led to a shift in public perception and policy regarding pesticide use. 11. Secondary Pests and Pest Resurgence Secondary Pests: Pests that are not initially harmful but become problematic when natural predators or competitors are eliminated by pesticides. Pest Resurgence: The re-emergence of pest populations after a pesticide application, often due to the elimination of natural predators or the development of resistance. 12. Two Types of Insect Pests 1. Economic Pests: Cause significant damage to crops, livestock, or human health. 2. Occasional Pests: Cause damage only under certain conditions. 13. Biological Control Methods Classifications: o Classical Biological Control: Introduction of natural enemies (e.g., parasitoids, predators) to control pests. o Augmentation: Increasing the numbers of natural enemies in an area. o Conservation: Protecting or enhancing the effectiveness of existing natural enemies. 14. Most Effective Insect Control Biological control is generally considered the most effective and sustainable pest control method, especially when integrated with other management strategies. 15. Insect Resistance to Insecticides Mechanisms: o Behavioral resistance: Insects change their behavior to avoid exposure (e.g., avoiding treated areas). o Physiological resistance: Insects evolve mechanisms to detoxify or excrete the chemical. o Genetic resistance: Insects evolve genetic changes that make them less susceptible to insecticides. 16. Insecticidal Formulations Types: o Dusts: Dry powder insecticides. o Liquids: Solutions or emulsions. o Aerosols: Fine sprays for quick application. Formulations differ in how they are applied, how long they persist, and their effectiveness. 17. How Insects Become Pests Reasons: o Monocultures: Large areas of the same crop make it easier for pests to thrive. o Introduction of non-native species: Invasive pests cause damage in new environments. o Lack of natural predators: Without natural enemies, pest populations grow unchecked. 18. Examples of Prominent Agricultural and Forest Pests Agricultural Pests: o Cotton boll weevil: Damages cotton crops. o Corn earworm: Damages corn crops. Forest Pests: o Mountain pine beetle: Destroys pine forests. o Asian longhorned beetle: Threatens hardwood trees.