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HERBIVORES: INSECTS AND PLANTS

Return to Entomology schedule

Read: DDP, Chap. 10, BTJ Chap. 4 pp 74-75

REFERENCES: Gilbert, L. 1982 Aug. Coevolution of a butterfly and a vine. Sci. Am. 247(2): 110

Arimura, G-I. et al. 2000. Herbivore-induced volatiles elicit defence genes in lima bean leaves. Nature 406: 512-515.

Barrett, S. 1987 Sep. Mimicry in plants. Sci. Am. 257(3): 76

Carson, W. and R.B. Root. 2000. Herbivory and plant species coexistence: community regulation by an outbreaking phytophagous insect. Ecological Monographs 70: 73-100.

Ehrlich, P. and P. Raven. 1967. Butterflies and plants. Scientific American (June) reprinted in Ecology, Evolution, and Population Biology.

Engler, H. et al. 2000. Preventing cyanide release from leaves. Nature 406: 144-145.

Gavloski, J. and R. Lamb. 2000. Specific impacts of herbivores...on young plants. Environ Entomol 29: 1-7.

Greene, E. 1989. A diet-induced…polymorphism in a caterpillar. Science 243: 643-646

Haddad, N. and W. Hicks. 2000. Host pubesence and...Papilio troilus. Environ Entomol 29: 299-303.

Karban, R. and I. Baldwin. 1997. Induced Responses to Herbivory. Chicago. Univ. Chicago Press. 319pp.

Levin, D.A. 1976. The chemical defenses of plants to pathogens and herbivores. Annual Review of Ecology and Systematics 7: 121-159.

Mitter, C. et al. 1991. Phylogenetic studies of insect-plant interactions: insights into the genesis of diversity. Trends. Ecol. Syst.6: 290-293

Rosenthal, G. 1986 Jan. The chemical defences of higher plants. Sci. Am. 254(1): 94

Rosenthal, G. 1983 Nov. A seed-eating beetle's adaptations to a poisonous seed. Sci. Am. 249(5): 164

Ryker, L. 1984. Acoustic and chemical signals in the life cycle of a beetle. Sci. Am. 250(6): 112

Stamp, N. and T. Casey. 1992. Caterpillars: Ecological and Evolutionary Constraints on Foraging. Routledge, Chapman and Hall. 548pp.

Van Zandt, P. and S. Mopper. 1998. A meta-analysis of adaptive deme formation in phytophagous insect populations. American Naturalist 152: 595-604.

DEFINITIONS

  1. Guild - a group of species in an ecological community that exploit the same resource(s) in a similar way
  2. Niche - the role of an organism in an ecological community, i.e. its "occupation"
  3. Habitat - where an organism lives (the type of community or set of physical conditions that define its "address")

FUNCTIONAL CLASSIFICATION

  1. Sap-tappers - feed on plant fluids, usually through a beak - aphids - scale insects - leafhoppers
  2. Pit-feeders - rasp holes in plant surface - flea beetles
  3. Strip feeders - chew leaves
  4. Leaf-tiers - bind leaves together before chewing or rasping pits
  5. Gall-formers - feed within aberrant plant growth, induced by the insect itself - Hackberry psyllid gall - Cynipid galls (oak galls)
  6. Leaf-miners - feed by chewing a gallery in the leaf
  7. Twig, bark, stem borers - chew gallery in stem or trunk
  8. Juice-lappers - feed on various plant secretions
  9. Pollen -feeders - eat pollen from flowers
  10. Nectar-feeders - feed on nectar from plants
  11. Flower-feeders - nectar & pollen - bees
  12. Seed slayers - mine or chew seeds - seed bugs - seed weevils
  13. Fruit-feeders - borers, suckers, miners, etc.

CLASSIFICATION BY HOST RANGE

  1. Monophagous - feed on only one species of plant (or a few closely related species)
  2. Oligophagous - feed on a range of plants in one family of a few related families
  3. Polyphagous - feed on a wide range of hosts

PLANT DEFENSES

plant defenses lecture notes - U. of No. AZ

  1. Attractants and repellants: Often plant secondary compounds ("non-essential", of sporadic occurrence, produced in large quantities, metabolically-expensive) may serve as antibacterial, antifungal defenses as well as anti-insect
     - studies on mountain birch and its herbivores reveal unexpected complexities
  2. Hormone mimics - both ecdysone and juvenile hormone are mimicked by plants, eg. juvenile hormone activity in wood of balsam fir
  3. Cyanogenic chemicals - legumes, cherries, etc.
        Heliconia
    butterfly can prevent release of cyanide (Engler 2000)
  4. Tannins - inhibit protein function, widespread, low-grade inhibitors
  5. Physical defenses - spines, hairs, toughness
  6. Sap flow - as seen in conifers against bark beetles
  7. Tolerance - plants can tolerate the loss of a fairly large part of their biomass without loss of reproductive output, etc. Important in economic situations - i.e., in deciding whether to apply a pesticide
  8. Escape in time and space - strategy of inconspicuous or ephemeral plants

HERBIVORE PLANT RELATIONSHIPS

  1. Host location is a crucial factor in the herbivore life cycle

    adult or nymph/larva may search for itself

    may place egg on host; a few provision a nest

  2. Visual cues very significant - leaf insects tend to react to yellow component of reflectance most attractive

    shape a factor as well

  3. Plant chemistry plays a key role

nutrients - sugars, starches, proteins and amino acids, fats, steroids, etc.

feeding stimulants - act once host is found

also oviposition stimulants

attractants - distinctive odors

repellants - odor, taste, feel

repellant for one species may attract another

 

PLANT-INSECT COEVOLUTION

Pollination - symbiosis, usually, but some cheat

mess and spoil types - beetles

moths & flies

bees most precise - euglossine bees and orchids

Herbivory - attack and defense adaptations leading to temporary advantage for plant or insect. Insects have complex, inducible systems of resistance to toxins, somewhat like the human immune system. Plants can also react to attack with inducible defenses. Recent work suggests that trees may even be able to react to attacks on nearby trees by increasing their defenses. Relationship dynamic. Insect that has overcome a particular chemical defense may use chemical as a cue to host location, or may sequester it as a defense.

Herbivore response to plant defenses

EXAMPLES OF HERBIVOROUS GROUPS OF INSECTS - search for these example groups on Bugguide.net