Exam 1 Flashcards
JBS Haldane
“… In inordinate fondness for beetles…”
beetle diversity
400K species of described species, 40% of all insects, and ~26% of all described living things.
insect diversity decline
- what is the baseline
- sampling error
- snapshot comparison
- causes
why are insects so successful?
- an exoskeleton for protection and to prevent desiccation
- variable size
- flight
- internal fertilization of an egg
- early colonization of land
- complete metamorphosis
why should we care about insects?
*decomposers
*pollination
food webs
ecosystem services
nutrient cycle
predation
medicine
commercial products
environmental quality
insect detriment
- disease (malaria, plague, typhus, sleeping sickness, yellow fever, dengue
- economic damage
- direct and indirect ( crop, forests, products)
Order Protura ‘coneheads’
- no eyes, wings, antennae
- prefer moist organic soil
- feeding habitat not well known
- mouthparts are styliform
order collembola ‘springtails’
- small
- furcula
- eyes absent or reduced
- moist habitat
- very common
order diplura
-small
-eyeless
- long, beaded antennae
- pair of caudal
- many feed on plant matter
800 spp.
order archeaognatha ‘bristletails’
- chewing mouthparts
- ametabolous development
- 250 spp
- under leaf litter
order zygentoma: silverfish and firebrats
- common in leaflitter
- common in basements
- 450 spp
- firebrats prefer warm places near fireplaces and heaters
evolution of mandibles
An early shift from monodondylic to dicondylic mandibles.
monocondylic: crustaceans, millipedes, centipedes, early hexapods, archeaognatha
more simple set of mandibles. crustaceans, millipedes, centipedes, early hexapods, archeaognatha
dicondylic mandibles
stabilize movements of mandibles and open new niches for insects
ametabolous
no change in body morphology during growth and development
hemimetabolous
having no pupal stage in the transition from larva to adult.
holometabolous
Complete, or holometabolous, metamorphosis is characteristic of beetles, butterflies and moths, flies, and wasps. Their life cycle includes four stages: egg, larva (q.v.), pupa (q.v.), and adult. The larva differs greatly from the adult.
apterygotes
ametabolous
exopterygotes
hemimetabolous
order ephemeroptera
- mayflies
- immature nymph stage
- unpolluted habitats with fresh moving water
- most species herbivorous
- subimago = subadult
- cannot fold their wings
- ~2000 species worldwide
order odonata
dragonflies and damselflies
- another ancient order with a nymph stage
- very large eyes
- greatly lengthened abdomen
- damselflies have wings held parallel at rest
- dragonflies have wings held perpendicular
- ~5000 species worldwide
Order Plecoptera
- adults do not disperse far from water.
- poor fliers
- nymph in well-oxygenated water
- adults feed off of soft plant tissue
- nymph feed on other invertebrates or detritus
hind wings are pleated and foldable
>2000 spp - stoneflies