Pests, Plagues & Politics Lecture 1 The Success of Insects

1. Pests, Plagues & PoliticsLecture 1 The Success of Insects

2. Key Points:The Success of Insects Evidence of Success • Numbers • Longevity • Diversity • Reasons for Success • Physical size • Flight • Fecundity

3. Insects by most measures, are the single MOST successful animal group in the entire evolutionary history of the earth!!

4. Evidence of Insect SuccessThe numbers Number of species: • 1,000,000 named • 5/6thof all known animal species Number of living [extant] individuals: • 1018 {one million billion} • 1015 ants!!! Biomass: birds = 1 lb per acre humans = 14 lbs per acre insects = one ton per acre {tropics} FYI

5. Evidence of Insect SuccessLongevity as a taxon Insects first appeared 400 million years ago (before dinosaurs!) Mammals: 200 mya Primates: 70 mya Genus Homo: 2 mya H. sapiens sapiens: 40,000 years ago FYI

7. Evidence of Insect SuccessEcologicalDiversity Insects are everywhere! • Terrestrial, fresh water & marine • Only polar ice caps without insects Latitude • butterflies at 80° North (within the Arctic Circle) • mosquitoes at 70° North • midges at 65° South (Antarctica) Altitude • Hemiptera @ 16,500 feet • Orthoptera @ 16,000 feet • Lepidoptera @ 15,000 feet • Hymenoptera @ 12,000 feet FYI FYI FYI

8. Evidence of Insect SuccessEcologicalDiversity Temperature Majority of insects arestenothermic& ectothermic(not always) Cold - Stoneflies & mosquito larvae active @ 0° C - Midge larvae recovered from immersion in liquid nitrogen (-190° C) Heat - Hot springs at Yellowstone with midge larvae active at 49°-51° C

9. Reasons for Insect Success Physical Size Insects are small (relative to humans) Average Insect = the housefly • (Muscadomestica) • 5-7mm

10. Reasons for Insect Success Physical Size Insects are small (relative to humans) • Extremes: • Smallest= 1/5th of a mm (1/100th of an inch) FYI Fairyfly next to a paramecium and an amoeba Family: Mymaridae, Fairyfly (a tiny wasp!) next to a match stick.

11. Reasons for Insect Success Physical Size Extremes: Largest = 6 in. Largest Wingspan = 12 in. Rhinoceros beetle Dynasteshercules • Brazilian moth Thysaniaagrippina

12. Meganeura • Extinctdragonfly (300 mya) • with a wingspan of 24 inches!

13. Reasons for Insect Success Physical Size Extremes: Longest = 22 in. Heaviest= 100 g or ¼ lb. (weight of small bird!) Chan’s MegastickPhobaeticuschani • Goliath Beetle FornasiniusFornasini

14. Reasons for Insect Success Advantages of being small 1) Less food to reach maturity • honey bee: egg to adult in 21 days on 300 mg of food (1/80th of an ounce) 2) Utilize small retreats to escape/avoid predators 3) Able to utilize a “small” food resource • an egg of another insect, for example!!

15. Damage caused by the larva of a leaf-mining insect. [the bug is INSIDE the leaf!] FYI

16. Reasons for Insect Success Flight Most, but not all insects are capable of flight APTEROUS (without flight) - Primitive groups that never had wings - Collembola - Silverfish PTERYGOTA = winged (most living insects) - Some Pterygota secondarily lost their wings i.e., Fleas

17. Reasons for Insect Success Flight Insects were the firstanimals to fly • as long ago as 330 mya • 100 million years before birds & mammals ADVANTAGES of Flight 1) Food Capture 2) Escape from Predators 3) Dispersal to new environments 4)SEX

18. Reasons for Insect Success Physics of Flight Wing Beat - butterflies 8-12 b/s • locust & grasshoppers 18-20 b/s • dragonflies 20-30 b/s [humming birds 30-50 b/s] • honey bee 190 b/s • mosquitoes 600 b/s • a midge >1000 b/s Speed of Flight • honey bee = 15 mph (22 ft/sec) • dragonfly = 35 to 40 mph

19. Reasons for Insect Success Fecundity FECUNDITY = fertility = fruitfulness = “r” = intrinsic rate of increase Paradigm of the house fly [Dr. Hodge] one female & one male in April Assume that all progeny live = 1.91 x 1020 flies by August!!! = enough flies to cover the earth with a layer of flies 47 feet thick!!!! …Wrong says Dr. Oldroy, only an area the size of Germany

20. Reasons for Insect Success Fecundity Dr. Herrick & his cabbage aphids: • 12 generations between March 31 & August 15 = • 822 million tons!!! • predators & parasites • finite food supply • weather • …Cute, but ridiculous • as these examples leave out:

21. Reasons for Insect Success Fecundity • The average “r” value for an insect is 100to150fertilized eggs in her life time. • Not so bad relative to humans, with the average female producing 400 eggs of which 2.2 will be fertilized.

22. Reasons for Insect Success Fecundity High Fecundity + a short life span + a short generation time = A group of organisms more responsive to short-term environmental change (selective pressures) = A group with pronounced evolutionary success!!

23. Key Points:The Success of Insects Evidence of Success • Numbers • Longevity • Diversity • Reasons for Success • Physical size • Flight • Fecundity

24. Back to lecture Glossary Extant – adj. Still in existence; surviving. Taxon - noun, plural: taxa (taxonomy) (1) Any group or rank in a biological classification into which related organisms are classified. (2) A taxonomic unit in the biological system of classification of organisms, for example: a phylum, order, family, genus, or species. Stenothermic - adj. Capable of living or growing only within a limited range of temperature. Ectothermic - adj. Of or relating to an organism that regulates its body temperature by exchanging heat with its surroundings; cold-blooded.