ENT1Lect72008 - Lecture 7 Insect Societies Termites Order...

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Unformatted text preview: Lecture 7 Insect Societies Termites Order: Isoptera Ants Order: Hymenoptera Honey Bees Order: Hymenoptera Lecture Questions • What is meant by social behavior? • Why are most social insects in just a few orders? • What is eusociality and what kinds of insects are eusocial? • What role does chemistry play in eusociality? • What can humans learn from models of social behavior taken from the insect world? What is meant by social behavior? •There are different levels of sociality in the insect world, ranging from: Individuals that provide parental care to their young (subsocial) to eusocial (“truly social”) insects that form ( truly social ) complex societies. • Characteristically, eusocial insects: •live in colonies formed by large work forces. •exhibit division of labor with cooperation between individuals. •may have specialized groups or “castes” with particular skills and duties. 1 Five Levels of Social Behavior in Insects Type Insect SubSub-social Cockroaches, beetles, bees, wasps Communal Bees, wasps QuasiQuasi-social Bees, wasps SemiSemi-social Bees, wasps Eusocial Honeybees, ants, termites, some thrips and aphids Five Levels of Social Behavior in Insects Type Behavior Eusocial •Individuals cooperate to build a nest. •Only a few individuals have functional ovaries and can mate and reproduce. •A strict caste system is evident. •Non-reproductive individuals feed and care Nonfor offspring produced by reproductive individuals. •Overlapping generations are present together in the nest. Castes in the Honey Bee Hive •Reproductive Individuals •Queen Bee (the single female reproductive) •Drones (male reproductives that leave the hive to mate with virgin queens and do not return). •Workers (All Female) •Guards and Undertakers •Pollen Collectors and Nectar Collectors •Cleaners • Nurses •Builders •Honey Ripeners •Field foragers 2 Castes in the Termite Colony •Reproductive Individuals •Queen (the single female reproductive) •King (the single male reproductive •Workers (Male and Female) •Attendants for the Queen. •Foragers •Builders •Cleaners • Nurses •Soldiers The Role of Chemistry •Caste Determination in the Honey Bee •Queen exerts chemical dominance by secreting queen substance from glands in her head. Passed to workers grooming her who pass it to other workers. •Queens live for approximately 5 years. As she ages, she produces less queen substance. Workers react by rearing new queens and swarming. •Immatures destined to become queens are exclusively fed royal jelly or bee milk secreted by glands in head of the worker. Larvae destined to be workers receive royal jelly for only 3 days. The Role of Chemistry •Caste determination in the termites •Chemical communications between the queen and her attendants provide the queen with a full report on the state of her colony. She lays eggs of the right type to fill the needs of the colony. The precise mechanisms are unknown. 3 The Role of Chemistry •Communication is one of the greatest keys to the evolutionary success of eusocial insects. •Chemical communication is widely used by all eusocial insects to provide diverse information. Architecture and Communication • Hexagons—Why? Hexagons— • Storage facilities: honey, pollen, brood • Mapping tools: Waggle Dance Why a Hexagon? • Efficiency – A hexagon uses less wax to create a shape with maximum volume – Hexagonal tubes use 18% less wax than triangular tubes, 7% less than square tubes • Maximizes use of space (compare to circular tubes) 4 A Bee-Space • Honey bees consistently build their honeycombs 1 and 3/8 of an inch apart. (Honeycomb at 1”, 3/8” as a passageway. passageway • Bee-space = in spaces greater than Bee3/8” bees try to build more honeycomb, in spaces less than ¼” bees close the space with propolis. propolis. The Birth of the Domesticated Bee Hive The Langstroth hive: Took advantage of the concept of the bee space with hanging honeycombs with a 3/8 inch passageway between. Design is used in most modern bee hives. 5 The Honey Bee Waggle Dance Combining Sensory Cues for Communication-Communication-The importance of the Honeycomb The Waggle Dance •THE ROUND DANCE = food is near (within 25 m of the hive). No directions. •THE WAGGLE DANCE = food further away (more than 100 m). Waggle dance = a flattened figure-of-eight. figure-of•Squeaks, buzzing and waggling attract “listeners”. ste e s •LENGTH of the straight center run indicates distance of the food source. •The ANGLE provides directions. •The number of honey combs passed = means of measurement. •Samples are given and floral fragrances shared to give info on quality (chemical). Paper Wasps: On the way to sociality 6 A Closer Look At Nest Use Larva Egg 7 The Hornet Nest, Yet a Different Design Ants as Architects: Aerial Evidence Small Fire Ant Mound Red Ant Nest in Forest Ants as Architects: Tunnels and Galleries The Queen’s Chamber 8 Argentine Ants g Why can they have such large colonies? Altruism, Consciousness, Models for Human Behavior and the Social Insect • Basis for altruism— altruism— – Genetic (Kin Selection) – Group Selection • Consciousness • Models for coordinated human activity – Emergency Response – Swarm Behavior 9 ...
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