Lecture 18 Flashcards
What is bilateral cannibalism?
- Wings became a nuptial gift
- Cockroaches munch on wings when mating
What are plant feeding insects called?
- Phytophagous
- Monophagous= specialist on 1 plant species
- Oligophagous= specialist on few taxa
- Polyphagous= feeds on many taxa
- MOST PHYTOPHAGOUS INSECT GROUPS are specialized except orthoptera
What are the challenges to plant feeders?
- gain and hold on to vegetation
- overcome desiccation
- Plant tissue is inferior nutritionally to animal/microbial food sources
- plants are not passive, have ways of deterring insects
- DESPITE THESE CHALLENGES, 1/2 INSECTS ARE plant feeders
Co-Evolution between plants and insects
-Started 300 mya
-two types, specific/pairwise coevolution and guild/diffuse coevolution
-Specific/pairwise coevolution described a tight coevolutionary relationship between two species
-Guild/Diffuse coevolution is where whole groups of species interact with other groups of species leading to changes that can’t be described as specific coevolution
-Over time with diffuse coevolution, insects may change hosts, therefore, plants can evolve defense capabilities and overtime, insects will be able to evolve past those defenses and the pattern continues
-ex. fig plant, fig wasp (wasp comes, lays eggs, larvae is able to grow, flowers also mature, male wasps go away, collect pollen, and flies to another fig tree in search of syconium in which to lay eggs, then dies)
75 million years of association; very specific association through coevolution and cospeciation; sensory reception for wasp for specific volatiles; morphology of guarding scales of ostiole
Plant Defenses
- Spines and hairs on leaves/stems
- tough leaves/stems
- Secondary plant compounds called allelochemicals which repel, inhibit feeding or oviposition. Also, have poison or reduce nutrient content of food
- Constitutive defenses are present at all times
- Induced defenses:response to feeding; deters herbivores and attracts enemies of herbivore
Induced Defenses
Talking Trees-One tree attacked releases volatiles which is received by another which then induces resistance
Mycorrhizal fungi underground
Types of Plant Feeding
- Leaf chewing
- Plant mining and boring
- Sap sucking
- gall inducing
- seed feeding
Leaf chewing
- Most diverse groups are Coleoptera and Lepidoptera
- Also includes orthoptera, hymenoptera, and phasmatodea(minor)
Plant mining
-Diptera, Lepidoptera, Coleoptera, Hymenoptera
Plant Boring
- Wood borers: Coleoptera
- Fruit borers: Lepidoptera, Coleoptera, Diptera
Sap sucking
Most of Hemiptera
-feed on xylem phloem
-filter chamber for water removal
(first stomach has filter chamber, second stomaches has enzymes, rectum has excess water some sugars leave body)
-damage plants in 4 ways: remove plant sap, excrete honeydew(sootymold), plant abnormalities, transmit plant pathogens
Gall Inducing
- hypertropy (cell size)
- Hyperplasia (cell number)
- Hemiptera, diptera, hymenoptera
- many types of galls
- new growth=active tissue
- salivary secretions, frass, accessory gland secretions
Seed Feeding
- high nutrition
- coleoptera, hymenoptera, hemiptera (heteroptera)
- Window of opportunity
Insects as Plant Pollinators Entomophily
- Coleoptera- Cantharophily
- Diptera: Myophily
- Lepidoptera(butterfly): Psychophily
- Lepidoptera(moths): Phalaenophily
- Hymenoptera(bees): Melittophily
- Hymenoptera(wasps): Specophily
- Hymenoptera(ants): Myrmecophily
How much in US agriculture?
20 billion
