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