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Hexapod Ecology
By Nigel Detablan
Photo obtained from: https://www.thinglink.com/scene/754022537674883074
- Coevolution both exerts selective pressures on each otherand evolves in response to each other
- Coevolution of plants and insects is exhibited in herbivoryand pollination
- In herbivory, plant evolves defenses and the insectresponds with counter offensives.
ApiaceaePhoto obtained from: http://www.interhomeopathy.org/sumbulus-moschatus-keeping-perfect-control
Photo obtained from: http://www.epharmacognosy.com/2012/04/biosynthesis-of-coumarin-and.html
Carrot worm
A female black swallowtail butterfly, Papilio polynexes, is attracted by these chemicals
Photo obtained from: http://ohioplants.org/families-apiaceae/
Photo obtained from: http://www.arbico-organics.com/product/celery-worm/problem-solver-guide
Photo obtained from: http://www.epharmacognosy.com/2012/04/biosynthesis-of-coumarin-and.html
- The great diversity of floral structure largely reflects adaptationsfor facilitating pollination
- In pollination, both participants evolve to maximize benefitsand minimize costs
- Adaptations include colors, odors, and nectars that attractinsects – some have high specificity
Photo obtained from: http://www.washington.edu/news/2014/06/26/foul-fumes-derail-dinner-for-hungry-moths/
Moth hovers over a flower
Monarch butterfly feeding on flower nectar
Photo obtained from: http://magnusonkimball.photoshelter.com/image/I0000x6OmLKtjxCw/
• Insects are capable of parasitic nutrition.
• Parasitism is common and has evolved manytimes.
• Juvenile or adult is parasitic so that differentstages exploit different food resources andhabitat
Adult – Parasitic Juvenile – Conventional methods
Adult flea feeding on a cat
Photo obtained from: https://extension.entm.purdue.edu/publichealth/insects/flea.html /
Larva feeding on fecal blood
GIF obtained from: http://fleascience.com/flea-encyclopedia/life-cycle-of-fleas/flea-larvae/what-do-flea-larvae-eat/
Adult – Conventional methods Juvenile – Parasitic
Screwworm fly feeding on nectar
Photo obtained from: https://en.wikipedia.org/wiki/Cochliomyia
Myiasis
Photo obtained from: http://www.monsterparent.com/wp-content/uploads/2014/12/b90b7980-547c-097f-cc8d-9bf568e12efc.jpg
• There are some that spend their entire life cycle on the host
Lice
Photo obtained from: http://www.medicinenet.com/head_lice/article.htm
• Parasitoidism combines features of parasitism and predation.
• Parasitoids are smaller than their hosts and remain incontact with them over long periods, but theyeventually kill and consume the host
• Hyperparasitoids are parasitoids that attackparasitoids
Three very large families of insects that aredominantly parasitoids
Braconidae (Family)Hymenoptera (Order)
Ichneumonidae (Family)Hymenoptera (Order)
Tachinidae(Family)Diptera (Order)
Braconid wasp parasitoidizing a tomato hornworm
Photo obtained from:http://bugs.bio.usyd.edu.au/learning/resources/Entomology/internalAnatomy/imagePages/parasitoidWaspLarvae.html
• Hexapods use chemical, tactile, visual, andauditory signals to communicate
• Communication is important to find mates,give warnings about danger, tell about foodsources and etc.
• Pheromones are chemicals used to signal conspecifics.They are used to attract one sex to the other.
Adult female gypsy moth Adult male gypsy moth
Photo obtained from: https://en.wikipedia.org/wiki/File:Lymantria_dispar_8-8-2006_19-20-14.JPG
Photo obtained from: https://en.wikipedia.org/wiki/File:Lymantria_dispar_MHNT_Fronton_Male.jpg
• Pheromones also mark trails or territories insome species.
Ants
Photo obtained from: http://mute-net.sourceforge.net/howAnts.shtml
Photo obtained from: http://pestworldforkids.org/pest-guide/ants/
• Bioluminescent flashings of fireflies, which function in sexualattraction, is a visual signal
Photinus
Photo obtained from: https://en.wikipedia.org/wiki/Photinus_pyralis
• Sound can be produced by stridulation or the vibration of a membrane. Instridulation, a rough, rasplike scraper is rubbed over a file to produce soundand is a characteristic of grasshoppers, katydids, and crickets.
• Function in sexual attraction and aggression
• Allomone is a compound released by a source organism that has anadverse effect on the target organism.
• E.g. Lacewing larvae release a gas that subdues the prey, and mostHymenoptera produce venom to kill or immobilize the prey
• Social organization, or eusociality, the highest development ofcolonial organization, has evolved in only two taxa of insects:
Isoptera Hymenoptera
Termites Ants Bees
Eusocial societies are recognizable by three chief characteristics:
1. Members of the society cooperate in caring for the juveniles
2. There is a reproductive division of labor, sterile individuals performing the physical labor while fertile is for reproduction
3. All eusocial insects exhibit some degree of polymorphism, and the different types of individuals in a colony are termed castes
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