A Bug’s Life

Entomology

• Study of insects

• Most successful and preponderant taxon

• Most diverse of taxon– Specially beetles: weevils

• Ants have largest biomass on globe

Arthropods

• Phylum Arthropoda• = jointed feet• Insects, spiders,

scorpions, sun spiders, ticks, mites, trilobites

• Sea spiders, crabs, shrimp, lobsters, amphipods, isopods, millipedes, centipedes

Arthropods

Characteristics

• Exoskeleton– Chitin

• Open circulatory system– Heart, ostia, dorsal blood vessel

• Double ganglionated ventral nerve cord

Insects

• Springtails• Silverfish, firebrats• Mayflies• Dragonflies, damselflies• Earwigs• Crickets, hoppers,

katydids• Roaches• True bugs

– Bed bugs

• Beetles– Dung, carrion, etc.

• Flies• Moths, butterflies• Fleas• Lice• Thrips

Relation to ecology

• How do insects communicate?

• CHEMICALS

Chemicals

• 2 types

• Pheromones: same species– 2 types– Releasers: elicit immediate response– Primers: modify physiological state

• Caste designation in termites

• Allomones: different species

Scheme

• Scheme similar to symbioses

• Sender/receiver

• +/+ → synomones

• +/- → allomones

• -/+ → kairomones

• -/- → antimones

Synomones (+/+) : Allomones

• Flower odors• Sweet smell• Foul smell

Synomones (+/+) : Pheromones

• Sex– Practically every insect

• Aggregation– Aposematics

• Anti-aggregation– Bark beetles

• Trail– ants

• Alarm– Ants– Aphids– Social wasps, bees

Defense Allomones (+/-)

• TONS of arthropods• Released from glands• Hymenopterans• Roaches• Dung beetles• Aquatic insects• True bugs

– Cosmopepla bimaculata– Triatoma spp.

Defense Allomones (+/-)

• Stick insects of North Am.• Bombardier beetle• Termites• Caterpillars

– osmeteria

• Vinegaroon• Millipedes• Anti-aphrodisiac pheromone

– Gnats, mussies

• Anti-oviposition pheromone– Leave “scent” → don’t oviposit– Egg mimic on plants

Defense Allomones (+/-)

• Sequestration– Caterpillars, moths,

butterflies– True bugs– Beetles

• Reflex-bleeding– Spanish fly

Allomones : Kairomones (-/+)

• Release of aphid alarm pheromone

• Human sweat → female mussies

• Leaf “scent” → oviposition/feeding

• Tritrophic Level Interactions

• Caterpillar → Leaf→ Parasitoid wasp

• Sound cues!– Crickets chirp → Parasitoid

flies