Beetles & hyperdiversity

Question 1

explain the Coleoptera order

Answer 1

• the beetles
• Most speciose insect order
• Defined by elytra (elytron singular)
• massive diversity

Question 2

coleoptera - explain their elytra

Answer 2

• elytra are forewings used for armor
• Hindwings only used for flight and they fold under elytra when not in use
• Not greatest flyers (vs odonatan, hymenoptera, diptera)
• Sacrifice flight efficiency for armor/protection

Question 3

coleoptera - massive diversity

Answer 3

By far more named species than any other group of organisms

Question 4

coleoptera: massive diversity - why are there so many beetles

Answer 4

• Apparently evolved with the Angiosperms, flowering plants
• Most speciose lineages are phytophagous (plant eating)
• But not clear why so many more beetles than other groups

Question 5

what do beetles do?

Answer 5

1. Beetles attack plants (usually as larvae)
2. Beetles are predators
3. Beetles are scavengers

Question 6

explain rarefaction curves

Answer 6

• method used to estimate beetle species
• the curve leveling off allows us to know the estimate total diversity

Question 7

beetle families - Carabidae

Answer 7

• ground beetles
• Generalist predators
• Often found under rocks, logs
• Catch in pitfall traps

Question 8

beetle families - Staphylinidae

Answer 8

• Rove beetles
• Short elytra, exposed abdomen
• Elongate ‘squirmy’ form, sometimes hold abdomen up ‘scorpion style’
• Speciose
• Typically, hunters or scavengers
• found under rocks, litter, etc. (also, pitfalls)

Question 9

beetle families - Scarabaeidae

Answer 9

• superfamily
• Many are dung beetles, the rest feed on plants
• Many have elaborate horns for male-male competition
• Can fold/unfold antennae

Question 10

beetle families: scarabaeidae - Dung beetles

Answer 10

• dung is resource – want to sequester it to protect resource for larvae
• Compete with other beetles and esp. flies
• May tunnel under dung to sequester it underground or roll it away
• Ecologically important for scavenging

Question 11

beetle families - Silphadae

Answer 11

• carrion beetles (also known as burying beetles)
• Nicrophorous species are local – have parental care
• ecologically important for scavenging

Question 12

beetle families: silphaadae - nicrophorous species

Answer 12

• Dig hole under carcass, carcass falls in and is buried
• Prepare carcass for larvae, stay and defend them
• Often have phoretic mites that kill fly eggs (mutualism) bc flies are competitors for carcass
• Why bury? Protect carcass from other scavengers

Question 13

beetle families - Lampridae

Answer 13

• fireflies
• Bioluminescence – light production
• Males use light signal for females

Question 14

beetle families - Elateridae

Answer 14

• click beetles
• Can ‘snap’ their prothorax against the mesosternum to shoot in the air to try to escape predators
• Some tropical spp. are bioluminescent

Question 15

beetle families - Curculionoidea

Answer 15

• weevils
• Largest insect family, 60,000 described spp.
• Long ‘snout’ (rostrum) with mandibles at end – penetrating drill bit
• Typically plant feeders, some pests

Question 16

Boring beetles

Answer 16

• boring = drill into wood
• Several families have larvae that bore into wood
• Develops over months-years, so can be transported as larvae in shipping crates, lumber, furniture, etc.
• High potential for invasion
• Larvae tunnel through cambium – cut off tree circulation, kill trees

Question 17

boring beetles - examples

Answer 17

• Burprestidae (Emerald ash borer)
• Cerembycidae (Asian long horned beetle)
• Curculionidae and Scolytinae (Bark beetle)

Question 18

boring beetles - Burprestidae

Answer 18

• Emerald ash borer
• likely to wipe out Ash in USA forests

Question 19

boring beetles - Cerembycidae

Answer 19

• Most Cerembycids bore through dead wood – not really pests
• a few, like Asian long-horned, attack live trees
• long horned beetle is threat to hardwood forests, esp. maple

Question 20

boring beetles - Curculionidae and Scolytinae

Answer 20

• bark beetles
• Adults bore into trees, oviposit, larvae burrow out through wood girdling the tree by cutting off sap flow
• Also introduce fungus to help digest wood, this further damages the tree
• Beetles produce aggregation pheromones

Question 21

boring beetles: Curculionidae and Scolytinae - explain their aggregation phermones

Answer 21

the pheromone attract more individuals to overcome resin defenses (single beetle not successful)

Question 22

boring beetles: Curculionidae and Scolytinae - how can the tree resist

Answer 22

• Tree can resist with resin, but drought-weakened trees are susceptible to the beetles
• Very cold winters (-30 F for 5 days) also keep beetle populations down

Question 23

boring beetles: Curculionidae and Scolytinae - how does climate change impact the tree’s resistance

Answer 23

• more drought and warmer winters mean more bark beetle damage (less sap, more beetles)
• Destroyed millions of acres of western forest
• Creates huge fire hazard, destroys habitat

Question 24

beetle families: Curculionoidea - Boll weevil

Answer 24

• major cotton pest
• early target of insecticides: in early 1900’s ~40% of all insecticide was targeted at boll weevil
• Overuse exposed limits, resulted in environmental damage of pesticides

Question 25

Curculionoidea: Boll weevil - 2 things ppl found that helped pest control

Answer 25

1. Discovery of mating pheromone led to mating disruption and also traps for monitoring
2. Weevil diapauses in dead cotton stems

Question 26

Curculionoidea: Boll weevil - how did the knowledge of diapause help pest control

Answer 26

• pesticide treatment right before autumn kills many, more effective than spraying through the summer
• plowing under old stems after harvest further kills the overwintering weevils