Beetles

1. Beetles • (EE, pp. 189-200)

2. Phylogeny of Hexapoda from p. 52 Coleoptera

3. Coleoptera Common name: Beetles (370,000 known world species (37.0%)) Derivation: Gk. koleos - sheath; pteron - a wing Size: Body length 0.1-180 mm; mostly under 25 mm Metamorphosis: Complete (egg, ;larva, pupa, adult) Distribution: Worldwide Number of families: 166

4. Key Features • very abundant and ubiquitous • front wings modified as rigid elytra covering the hind wings (greatly contributes to their success) • prothorax usually large, and distinct from the head and rest of the body • many species are plant pests • the largest order

5. “All biology tells us about the nature of God is that he has an inordinate fondness for beetles” J.B.S. Haldane founding father of population genetics (along with Ronald Fisher and Sewall Wright) The most successful order (found in every conceivable terrestrial and freshwater habitat) • approximately 40% of all known insect species are beetles • 30% of all known animals are beetles • there are more species of beetles than there are species of plants

7. Elytra are a key feature (front pair of wings toughened and acts as a wing case) • protect the membranous hind wings • in all species the elytra meet down the mid-line of the body (sometimes permanently fused) • elytra usually extend to cover the whole of the body, but in some cases they are shortened

8. campodeiform apodous scarabaeiform eruciform Beetle eggs and larvae(most female beetles lay eggs - and larvae are highly variable in appearance) • all larvae have toughened head capsules, with forward facing biting mouthparts and short antennae (4 segments) • four distinct larval types -

9. blister beetle (meloid) rhipicerid What do beetles eat?(many are herbivorous or carnivorous) • some are saprophagous - eat decaying organic matter • many develop in wood, dung, carrion, and fungi • some are endoparasites, e.g. in cicadas, bees and wasps, cockroaches and grasshopper eggs

10. Coleopteran Suborders

11. Suborder Archostemata(the basal Coleopteran Suborder) • first appeared 290-248 MYA (Permian) • mostly found in decaying wood, feeding on fungi

12. ground beetles (carabid) tiger beetle (carabid) Suborder Adephaga(second largest beetle suborder - more than 40,000 known species) • mostly predaceous (greek word “adephagos” means “gluttonous”) • both terrestrial and aquatic • most members belong to family Carabidae diving beetle (dytiscid)

13. Diving beetles(there are more than 3,500 species of diving beetle (Dytiscidae)) • both larvae and adults are carnivorous • they store air under their wing cases (elytra) and when they need more air they come to the surface, tail first

14. Whirlygig beetles(there are about 800 species (Gyrinidae)) • eat mosquito larvae - catch with front legs, while the middle and hind legs are paddle-like • move in a characteristic circular, jerky way over the surfaces of ponds and slow moving streams • eyes divided horizontally into two zones - one for above water, one for below water

15. Ground beetles(there are about 25,000 species worldwide (Carabidae)) • most are dark colored, but many are metallic or brightly colored • major predators and they are important elements in the food chain • useful indicator species in conservation studies

16. sphaeriusid hydroscaphid Suborder Mxyophaga(small beetle Suborder - sister group to Polyphaga Suborder) • aquatic or associated with wet habitats • algal feeders

17. Suborder Polyphaga(largest beetle Suborder - about 300,000 (90%) of described species) • terrestrial and aquatic habitats, mostly herbivorous • aquatic lineages have evolved several times

18. Burying beetles(silphids locate carcasses and bury them by digging out the soil beneath ) • burying prevents competition from fly maggots • parents cooperate - sometimes the male has multiple partners • sometimes take-overs occur at the height of breeding season - adults evicted and eggs are killed

19. Scarab beetles(more than 20,000 species in the family Scarabaeidae) • 3-7 segmented, fan-like or lamellate antennal clubs • powerful legs armed with teeth on the outer egde, an adaptation for digging • dung beetles are important recyclers - larvae and adults eat dung, and return nutrients to the soil

20. Jewel beetles(typically inhabitants of woodland and forest (Buprestidae)) • mainly found in the tropics - majority are metallic green, blue and red with contrasting markings • some species contain paired infra-red detectors - heat sensing organs that allow insects to hind suitable mating and egg laying sites from several kilometers away

21. Leaf beetles(more than 30,000 species worldwide (Chrysomelidae) - all herbivorous) • tend to have a large, fairly smooth, rounded appearance, and many are brightly colored • larvae feed externally, or bore into stems, roots and leaves • many are pests - some are used in biological control programs against weeds (e.g. St. John’s wort)

22. Ladybird beetles (more than 30,000 species worldwide (Coccinellidae)) • predaceous on soft-bodied insects, such as aphids, mealybugs and scale insects • seek out colonies of aphids using visual and olfactory cues • adults use relex bleeding - toxic fluids ooze of of joints (especially the knees) and deter would-be predators

23. Anthonomus grandis Cotton boll weevils(caused an estimated $14 billion in loss in yield since it arrived in 1892) • measures about six millimeters and feeds on cotton buds and flowers • migrated into the US from Mexico in the late 19th century and had infested all US cotton-growing areas by the 1920’s • boll weevil eradication plan (1978) has allowed cultivation to resume

24. Bugs as pests to trees(bark beetles (Scolytidae) and Asian long-horned beetle (Cerambycidae)) • bark beetles bore into the cambium of trees - feed and lay eggs (characteristic tracks left by larvae) • Asian long-horned beetle, from China, attack maple trees (first discovered in NY in 1996 - also in Chicago)

25. Southern pine beetle(smaller than a grain of rice - one of the most serious pests of pine)