Lepidoptera and herbivory Flashcards

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1
Q

what are the general features of lepidoptera

A
  • Most primitive moths have chewing mouthparts (like Trichoptera), but vast majority have highly modified, sucking mouthparts in a coiled proboscis
  • Holometabolous – full metamorphosis
  • Larvae (caterpillars) are important herbivores: often limit plant growth
  • Adults are second most important pollinator group (behind bees)
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2
Q

lepidoptera - explain the ecological importance

A
  • Larvae niche: to eat the leaves of plants to grow and pupate
  • Adult niche: to eat the nectar of plants for food while pollinating plants
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3
Q

lepidoptera: ecological importance - how do the niches effect plants

A
  • larvae niche: herbivory on plants are not beneficial
  • adult niche: pollination is beneficial and helps plants reproduce
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4
Q

explain the Lepidoptera Tree of life

A
  • Most groups pre-date flowers
  • But explosion of diversity occurs after the evolution of angiosperms
  • “Fenemies” with angiosperms: pollinate as adults, but consume as larvae
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5
Q

lepidoptera - explain their larvae

A
  • caterpillars
  • they have prolegs
  • important ecology
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6
Q

lepidoptera: larvae - proleg

A

caterpillars have 6 legs on thorax – can have extra on abdomen

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7
Q

lepidoptera: larvae - ecology

A
  • Massive force for herbivory, structuring plant communities
  • Important food source for parasitoids, predatory insects, birds, etc…
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8
Q

lepidoptera - Monarch butterflies

A
  • Migrate from overwintering sites in CA and Mexico through USA over several generations, then return at end of fall
  • Rely on milkweed as host plants
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9
Q

lepidoptera - Bombyx mori

A
  • the silk moth
  • Domesticated
  • Silk from cocoon
  • Huge historical importance
  • Specialist on mulberry trees
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10
Q

lepidoptera - explain the scales on their wings

A
  • their scales combine pigment and structural color
  • Color produced by refraction of light
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11
Q

lepidoptera - what are the function of color in wings

A
  1. Crypsis (camouflage)
  2. Warning coloration
  3. Fake warning coloration
  4. Startle predators – eyespots
  5. Species identity/sexual signaling
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12
Q

lepidoptera: wings - crypsis (camouglage)

A
  • Peppered moth example from England
  • Black moth is rare and white one is common
  • after industrial revolution (everything became black) , the black one became a more common one with the white one decreasing
  • After air quality got better, white one became more common as everything went back to a normal color
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13
Q

lepidoptera: wings - what are the two types of warning coloration

A
  • Mullerian mimicry
  • Bastesian mimicry
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14
Q

lepidoptera: wings - define mullerian mimicry

A
  • honest mimicry
  • multiple chemically defended species use the same signal
  • some insects use similar warning coloration to enhance the signal
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15
Q

lepidoptera: wings - define bastesian mimicy

A
  • fake warning coloration
  • some species without chemical defense copy the signal
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16
Q

lepidoptera: wings - honest mimicry examples

A
  • The monarch butterfly
  • Viceroy and Milkweed bug
17
Q

lepidoptera - eyespots

A
  • Crypsis on forewings, hindwings exposed as last resort
  • Hindwings are exposed quickly to suddenly startle predator, buy moments for escape
18
Q

lepidoptera - Some Lepidoptera have camouflaged wings, while others have extremely bright and noticeable wings. Explain how these divergent wing types could each be selected for.

A
  • Bright color – it is selected for when an animal eats a toxic Lepidoptera that has the coloration. Then the predator can avoid the other lepidoptera that has the coloration (even if they are not toxic)
  • Camouflaged – it is selected for as the predators are not able to see them
19
Q

explain Herbivory

A
  • its a major force reducing plant fitness
  • not just Lepidoptera
  • Almost all caterpillars are herbivores, but not all herbivores are Lepidoptera caterpillars
20
Q

herbivory - non-lepidoptera herbivore examples

A
  • Hemiptera sap suckers
  • Locusts
  • Sawflies
  • Also many Diptera and coleoptera larvae
21
Q

explain Herbivory and the co-evolutionary chemical arms race with plants and adaptive radiation

A
  1. Insects can eat plants
  2. Plant evolves chemical defense
  3. Insect overcomes chemical defense
  4. Plant evolves more elaborate chemical defense - cycle starts over again
22
Q

herbivory and co-evolutionary arms race - insect can eat plants

A
  • new ‘adaptive zone’
  • insect undergoes ‘adaptive radiation’: evolve into new species to exploit new niche
23
Q

herbivory and co-evolutionary arms race - plant evolves chemical defense

A

plant enters new adaptive zone (free of herbivory) and undergoes adaptive radiation

24
Q

herbivory and co-evolutionary arms race - insect overcomes chemical defense

A

new adaptive zone – access to all that food

25
Q

Extreme example of the result of the arms race

A

Monarch and Milkweed

26
Q

extreme example of the result of the arms race - what does milkweed produce

A
  • Milkweed produces cardiac glycoside
  • Disables Na/K pump and causes a heart attack
27
Q

extreme example of the result of the arms race - how does the monarch butterfly eat the milkweed

A
  • Monarchs have a mutation in Na/K pump, confers resistance
  • Can now sequester plant defensive chemicals, use for defense
28
Q

extreme example of the result of the arms race - what is the secondary result

A

Mullerian and Batasian mimicry

29
Q

extreme example of the result of the arms race - how does this show convergent evolution

A

Insects from 6 orders have similar Na/K mutation

30
Q

arms race - explain the evolution of the toxin resistance

A
  • Evolution of toxin resistance uses same three amnio acid substitutions (in alpha subunit of Na pump), despite multiple evolutionary origins in different insect species
  • Inserting these into Drosophila makes them resistant
31
Q

explain the relationship between bullhorn acacia tree and ants

A
  • Plants “paying” ants for private security with room and board
  • Tree houses and feeds ants in return for herbivore protection
  • The ants on plant get food and a nest, ants then attack any organism that tries to eat the plant