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Holometabola I

Holometabola I. Lecture 7. Some major characteristics of Hexapoda : Maxillary plate present 3 body parts (head, thorax, abdomen) 3 thoracic segments each bearing a pair of legs Legs composed of 6 segments 11 maximum abdominal segments Trachea

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Holometabola I

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  1. Holometabola I Lecture 7

  2. Some major characteristics of Hexapoda: • Maxillary plate present • 3 body parts (head, thorax, abdomen) • 3 thoracic segments each bearing a pair of legs • Legs composed of 6 segments • 11 maximum abdominal segments • Trachea • Some major characteristics of Insecta: • External mouthparts • Malpighian tubules • Annulated antennae • 2 pretarsal claws articulated with tarsus • Johnston’s organ • Ovipositor • Posterior tentorial arms fused

  3. Holometabola • Endopterygota (11 orders) • Complete metamorphosis (egg, larva, pupa, adult) (video) • Three strongly supported groups: • Amphiesmenoptera: Trichoptera and Lepidoptera • Antilophora: Diptera, Mecoptera, Siphonaptera • Neuropterida: Neuroptera, Megaloptera, Raphidioptera • Coleoptera probably sister to Neuropterida • Strepsiptera position problematic • Hymenoptera position questionable

  4. Neuropterida • Three closely related small orders: • Neuroptera (lacewings, antlions, owlflies) • Megaloptera (alderflies, dobsonflies, fishflies) • Raphidioptera (snakeflies) • Multisegmented antennae • Large and separated eyes • Mandibulate mouthparts • Many species predaceous

  5. Neuroptera(neuro, nerve; ptera, wings [referring to the wing veins]) • Lacewings, owlflies, antlions • Prothorax often larger than meso- and metathorax • Wings held roof-like over abdomen at rest • For and hind wings subequal with numerous cross-veins and distal twigging of veins, without anal fold • Immature stages predominantly terrestrial

  6. Lacewing Owlfly Mantisfly Antlion

  7. Antlion (Myrmeleontidae) • Sit-and-wait ambush predator using a sand trap • Grooved mandibles for piercing and sucking fluid from prey • video

  8. Mythical flower, Udumbara? Lacewing eggs

  9. Megaloptera(megas: great, ptera: wings) • Alderflies, dobsonflies, fishflies • Prothorax only slightly longer than meso- and metathorax • Fore and hind wings subequal with anal fold in hind wing • Immature stages aquatic with lateral abdominal gills

  10. Corydalidae (dobsonfly, hellgrammite) Sialidae (alderfly)

  11. Dobsonfly mandible function? Male-male competition Possible sexual selection

  12. Raphidioptera(rhaphis: needle, ptera: wings) • Snakeflies • Prothorax much longer than meso- and metathorax • Fore wings rather longer than otherwise similar hind wings, without anal folds • Immature stages terrestrial

  13. Diversity • Neuroptera: ~5750 species, 16 families • Megaloptera: ~280 extant species, two families (Sialidae and Corydalidae) • Raphidioptera: 228 extant species, two families (Inocellidae and Raphidiidae) Winterton et al. (2010) Systematic Entomology

  14. Strepsiptera(strepsi: twisted; ptera: wings) • Endoparasitoid (Blattodea, Mantodea, Orthoptera, Hemiptera, Hymenoptera) • Males with large head • Antennae with branches • Fore wings stubby, hind wings fan-shaped • Female larviform, inside the host • ~ 500 known species

  15. Development • Hypermetamorphosis – larvae changing body forms as they mature • Young highly mobile larval stage – triunguloid • Once inside the host, molt into internal larval form • Females larviform, remain inside host, attracting males • Embryos develop within female’s body • Triunguloid larvae escape the brood

  16. Phylogenetic position debate“Strepsiptera problem” • Close to Coleoptera? • Postmotor flight • Hypermetamorphosis similar to certain Coleoptera • Some molecular evidence • Close to Diptera? • Fore-wing-derived haltere • Some molecular evidence • Close to Neuropterida? • Most recent molecular evidence

  17. Coleoptera(coleo: sheath; ptera: wings) • The largest order of insects • ~40% of known species in Hexapod • More than 340,000 species described • Extremely variable biology, ecology, habitats, etc. • Most distinctive feature: elytra

  18. Diversity • 4 suborders: Archostemata (40 sp.), Adephaga (37,000 sp.), Myxophaga (90 sp.), and Polyphaga (>300,000 sp.) • 17 superfamilies, 168 families Hunt et al. (2007) Science

  19. Archostemata and Myxophaga • Two smaller suborders • Archostemata • Ommatidae, Crowsonielliade, Cupedidae, and Micromalthidae • Labrum fused to head capsule • Possible sister to the remaining Coleoptera • Many wood-boring larvae • Myxophaga • Lepiceridae, Torridinocolidae, Hydroscaphidae, and Sphaeriusidae • Riparian, aquatic beetles • Fusion of pretarus and tarsus • Probable sister to Polyphaga

  20. Adephaga • Hydroadephaga (diving beetles and whirligig beetles) and Geadephaga (ground beetles and tiger beetles) • Larval mouthparts adapted for liquid-feeding • Adults have notopleural sutures visible on prothorax • Six visible abdominal sterna • Pygidial defense glands widespread Carabidae Dystiscidae Gyrinidae Haliplidae

  21. Bombardier beetle defense • All carabid beetles have dischargeable defensive glands. • Capacious sacs, lying side by side in the abdomen and opening on the abdominal tip • Diverse toxicants are produced at high concentrations (acids, aldehydes, phenols, and quinones) • Most carabids are able to eject these fluids forcibly, in the form of sprays. • Hydroquinones and hydrogen peroxide in one chamber, catalases and peroxidases, in another chamber, mix to produce explosive, 100°C spray • Video Eisner T , Aneshansley D J PNAS 1999;96:9705-9709

  22. Polyphaga • >90% of beetle diversity • Prothoracicpleuron invisible externally • Transverse fold of hind wings never crosses MP • Hind coxa mobile • Staphylinoidea (rove beetles), Scarabaeoidea (scarab beetles), Hydrophiloidea (water scavenger beetles), Byrrhoidea (pill beetles), Bostrichoidea (auger beetles), Buprestoidea (jewel beetles), Elateroidea (click beetles), Cucujiformia (fungus beetles, grain beetles, ladybugs, longhorn beetles, etc.) Staphylinidae Scarabaeidae Hydrophilidae Bostrichidae Byrrhidae Elateridae Buprestidae Cucujidae

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