Lecture 4 Insect Orders PDF

Introducing the insects: the orders Ent 104 Johnson Tree of Life 1. Where are the insects in the tree of life? 2. What are their closest relatives? 3. What forms do they come in? Schierwater et al 2009 Invertebrates No backbone Not an evolutionary group A functional group Not necessarily closely rel...

Introducing the insects: the orders Ent 104 Johnson Tree of Life 1. Where are the insects in the tree of life? 2. What are their closest relatives? 3. What forms do they come in? Schierwater et al 2009 Invertebrates No backbone Not an evolutionary group A functional group Not necessarily closely related Sea stars are closer to vertebrates than to insects Many fundamental differences in their biology How to classify animals? By similarity Morphology Development By evolutionary history Monophyletic groups Share one common ancestor Arthropods Major Classes 1. Spiders, mites, ticks, scorpions(Arachnida) 2. Crabs, shrimps (Crustacea) 3. Centipedes (Chilopoda) 4. Millipedes (Diplopoda) 5. Insects (Insecta or Hexapoda) What is this? Horseshoe crab Is it an arthropod? Which is it closest to? Insects Arachnids Crustaceans Centipedes / millipedes What are insects? “All insects are arthropods, but not all arthropods are insects.” Insects have: Exoskeleton Jointed legs Segmentation Ventral nerve cord Dorsal blood vessel What separates insects from other arthropods? How many body segments and legs? Insects: 3 / 6 Arachnids: 2 (or 1) / 8 Crustaceans: 3 / variable Centipedes: ≈ 15 / 30 One pair of legs per segment Millipedes: 11-100 / 30-750 Two pairs of legs per segment Evolutionary history is what really separates them They are a monophyletic groups The Hexapods: 6 legged arthropods Zygentoma: Wingless No metamorphosis Mostly scavengers Some are pests Few hundred species? Odonata Dragonflies and damsel flies About 5500 species Fixed wings Aquatic predators as juveniles Flying predators as adults Haven’t changed much in a very long time Mayflies About 3000 species Fixed wings Aquatic Herbivores mainly Two molts Subimago, imago Adults short lived Don’t feed Mate and die Can be enormously abundant for a brief period of time Mayfly madness Dermaptera Earwigs About 2000 species Hemimetabolous Incomplete metamorphosis Juvenile looks like adult Mostly scavengers Some predators and herbivores Most have parental care Orthoptera Crickets, grasshoppers, catydids hemimetabolous About 27,000 species Ubiquitous herbivores Model systems for many aspects of reproductive biology Calling crickets, for example Mantodea Preying mantises About 2500 species All predacious Many with amazing camouflage Mantid love How is this possible? Whey doesn’t the male die immediately and stop mating Circulatory system Does not transport oxygen in insects Is not closed Low pressure Distributed nervous system Many small brains instead of one big one All the information needed to mate is in a small brain in the abdomen Why do the males allow it? Can’t do anything about it? Non-adaptive explanation Nuptial gift? Parental care The gift increases quality of eggs Phasmatodea Walking sticks About 3000 species hemimetabolous Strict herbivores Make their own cellulases Highly camouflaged Often toxic Blattodea Roaches and Termites About 4500 species of roaches 3000 species of termites Hemimetabolous Most are not pests Omnivorous Termites eat wood Largest colonies are fungus growers Thysanoptera Thrips About 6000 species hemimetabolous Tiny sucking insects Predators and herbivores Some vector plant diseases Hemiptera True bugs About 75,000 species All have piercing and sucking mouthparts Including many common groups of predators and herbivores Aphids, leafhoppers, kissing bugs, cicadas, scales, etc Many pest species Scales, leafhoppers, etc Neuroptera Lacewings holometabolous Mostly predacious insects As juveniles and adults Some look like flying mantises Many are brightly colored Mecoptera Scorpion flies Not flies but part of a clade including flies, fleas and themselves About 600 species Studied for their elaborate mating biology Hymenoptera Sawflies, Wasps, ants, and bees > 150,000 species Most primitive group are herbivores sawflies Most are parasitoids in terms of number of species All have ovipositors Aculeates have modified ovipositor that is a stinger Include most of the highly social insects Coleoptera Beetles Most speciose group About 400,000 species holometabolous Highly varied in lifestyle Hard cuticle Elytra Forewings are armored Siphonaptera Fleas 2500 species Holometabolous Closest to flies Blood sucking jumping insects Mostly mammalian parasites Few on birds Vector diseases plague Lepidoptera Butterflies and moths Second largest group, about 200,000 species Holometabolous Highly variable behavior Migratory, mating biology, etc Major group of pollinators Tend to be attracted to tubular flowers with strong sweet odors Moth flowers are lightly colored Butterfly flowers are often red, yellow or blue Some species are endangered because of over collecting Diptera Flies, gnats, mosquitos Large group, 125,000 species holometabolous One pair of wings Hind wings are halteres Used for precise control of flight Many are disease vectors Many predacious species but lifestyles are highly varied Mosquitos, gnats, midges, horse flies, crane flies, blow flies