Pesticides and Insects: An In-depth Look at DDT and Insect Classification - Prof. Karl Esp, Study notes of Animal Biology

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Insect Enemies Video  Everything has insect enemies o Livestock (lice, ticks, fleas) o Grains (weevil houses) o Fruits and vegetables (worm)  Spread human, plant & livestock disease

DDT use in the 1940s and 50s
1. A new way to collect insects
2. Add DDT to gin  happiness – Mickey Slim
3. A miracle chemical
4. Led to an “Era of Optimism”
5. Farmers: “when the chemicals came along… you had your crop”

Pesticide  A substance/chemical used to kill pests

Insecticide  Substance that kills insects

DDT  Chlorinated hydrocarbon  Developed by Swiss  Used in WWII  1942: o DDT was sent to US by Swiss o a secret army lab was set up in Orlando tested DDT against lice (which spread typhus) o US army first used DDT in N. Africa and Italy
Video:
1. New technology right after WWII  pesticides, plastics, fertilizers
2. DDT saved millions of lives in WWII  1st war where enemy killed more than disease  DDT was used to control typhus
3. Massive growth in chemical industry
4. Patuxent Research Refuge MD- “DDT kills birds”
5. Chemists and Entomologists did not ask why DDT kills insects
6. DDT massive use on US farms (know it INCREASED)  1945 125 million lbs / yr  1955 600 million lbs / yr
 is fat soluable  causes reduced calcium in birds  banned in 1972  production continued  still used across the world
DDT Biomagnification  DDT is trapped in animal fat  As DDT travels up the food chain in concentration

Pesticides  Contaminate groundwater  Persist in deep soil because low O2  Most are untested for cancer  Cancer test are for one pesticides, but most crops get several P

Pesticides and Cancer  Farmers are at higher risk especially migrant workers  Does long-term exposure cause cancer?  Most P have not been tested for cancer  Synergistic- 2 or more P may act together and be worse than one alone

David Pimentel- hidden costs  Dept. of Entomology (economic- dollars and cents of ENTO)  Cornell University  Each year 4 billion is spent in US on pesticides  Increases yield= 16 billion  ***Less than 10% of pesticides applied to crops reach target pest

UGA student suffers from pesticide spraying in her dorm
She works in GA legislature and this leads to new state buildings must pst notice when pesticides are sprayed

migrant workers are often exposed to pesticides
Pesticide Treadmill  insect becomes resistant to pesticide o either must apply more pesticide or apply more toxic pesticides
U.S. spends a lot less of our personal incomes on food than in many other parts of the world

Pesticides and Children  pesticide levels are five times too high  developing bodies are more susceptible  residue levels calculated for adults  balance health v. profit
some pesticides mimic human sex hormones  1990: sperm count is half what it was in 1940  1990: testicular cancer twice the rate of 1970  DDT exposure can increase chance of getting breast cancer
Our Stolen Future by Theo Colborn (1996)  about the danger of environmental estrogens o man-made chemicals in the environment mimic estrogen hormones  in the body, hormones interact with a receptor in a lock and key fashion o chemical fits into receptor site and acts like hormone. o Chemical blocks action and affects hormone metabolism
Lake Apopka in Florida- on test  major DDT spill in 1980  caused a decline in number of alligators  75% of alligator eggs are dead  25% of male alligators have small penis and wouldn't be able to reproduce  many male turtles are “intersex”- half male, half female
DES: a synthetic estrogen  from 1940-1970, DES was given to 5 million pregnant women to reduce miscarriages  it was given to girls who were “too tall,” had acne, and to stop flow of mother's breast milk  given to chickens and cows to promote growth  in 1971: women whose mothers took DES are much more likely to develop vaginal cancer  Bacteria produce toxic protein which kills insect  B.t. protein is not toxic to higher animals  Current use gypsy moth in N. GA  B.t. o Must be eaten o Toxic destroys insect stomach o B.t. does not act slow o New strains are being sought  Attacks insects  Anthrax is also Bacillus
4. Viruses that attack insects  are very specific, only a few insect species are attacked by each V  no effect on higher animals  multiply in great quantities in host insect  act too slowly pest insects lives for several days after eating V
UGA and American Cyanamid  Mite Toxin is insect specific  Insect gene for MT into virus DNA  *** Oest insect dies very quickly  virus still has narrow host range  no effect on humans or other animals  Also use toxins from scorpions and spiders
5. Short Generation Time  2 advantages o increased genetic variation o better utilization of limited food source
6. Specialization in life style  plus= develop special skills
7.Solve water problem  extract water from host sugar  C6H12CO2  6CO26H20+ energy  Limited water evaporation  Circular Lipids o Prevent dehydration o Sex recognition o Nestmate recognition o Host recognition  Limit water excretion o Aquatic animals- ammonia o Mammals- urea o Insects- uric acid (UA)  Water insoluable  Nontoxic
Biological Classification  Arrangement of living organisms into categories
Taxonomy  Classifying organisms into categories  Carolus Linnaeus o Swedish naturalist 1973 o Linnaean binomial system (genus species) o Binomial nomenclature  **Phylum – Arthropoda  **Class- Insecta  **Order- Diptera  Family- Muscidae  Genus- Musca  Species- Domestica
Species  Organisms that closely resemble one another and can produce fertile offspring
Scientific name (genus species)- musca domestica (house fly)
 Exoskelton  Jointed appendages allow for specialization  Montana o Bears and people compete for space o Bears have become a danger o Bears need to find “old”food sources o Bears now feed on a tiny moth  Environmental Concern Threat to Montana butterfly o M larvae fed milkweed with pollen form B.t. corn die o Pollen may blow from B.t Corn to nearby plants and cause death of M o Field studies show pollen does not go far
Insect Walking  6 legs as 2 alternate tripods  Insect wings o Most adults have W o Primative insects- wings don’t fold o Advanced- wings fold and get away form predators  Insect nutrition o Carbs o Proteins- amino acids o Insect and human digestive enzymes are the same  Insect cuticle o Main component is chitin o Chitin= amino sugar polymer  Insect circulatory system (ICS) o Open system o Hemolymph= insect blood  Distributes nutrients and hormones  Hormone o Chemical signal that is:  Formed in special cells  Travels in body fluids  Interacts with target cells  Pheromone o Chemical produced by animal that affects another animal of same species o Types:  Sex  Alarm  Aggregation: attract others to food (bark Beetles)  Trail: follow leader to find foods (ants) Gypsy Moth  Female releases sex pheromone  Male has larger antennae (a) than female  Male uses A to detect P and follow plume up wind  If wind changes M turns to find P  M can find F 5 miles away

Insect Chemical Ecology  The relationship between a chemical, an insect, and the insect’s environment
Thomas Eisner  Dept of Entomology  Cornell University
1. A black beetle is attacked by ants
2. Bombardier beetle (BB) is not attacked
3. BB sprays toxic chemical from abdomen (A)
4. Mouse kills BB; forces end of A into soil
Bombardier Beetle  Chemical reaction takes place in special glad in the abdomen  Reaction produces: Quinones**** + heat + oxygen + noise!!  The toxic spray can be aimed
Bolas Spider  Spider spins a silk strand with sticky ball on end  Throws ball at prey & then reels it in  Catches moths of only one species  All moths are males  There is greater biodiversity in tropics o 1 tree in peru o 43 species of ants = to # of all plant species in the UK
Forest Canopy (FC)  Many unknown species of insects are in FC  Get in FC with ropes, cranes and walkways
How many insect species are there?  Terry Erwin o Smithsonian institue o Washington DC
1 million species
1.82 million plant and animal (estimate)  between 10-30 million species o look at 1 tree in Panama o Fog tree with pesticide o Find 1200 beetle species o **163 are host species o ** there are 50,000 tropical trees o ** 8 million beetles o **Beetles- 40% arthropods o Therefore total 20,000,000 o **ground dwelling = 10 million o ** total tropical arthropods = 30 million o **between 10 mill and 30 mill insect species on earth
EO Wilson  The theory of Island Biogeography o Deforestation creates islands o How many species can exist in such “islands” o How big should protected national parks be?  Loss of Biodiversity (B) due to habitat destruction  Species loss o Dinosaur age= 1/1000 years o ****Today 1/day  food plants have loss B o ***1970 corn blight in US o $5 billion in damage o
Mutualism  Relationship between 2 species usually involving coevolution
Coevolution  Occurrence of genetically determined traits in 2 species selected by the change in another
Dan Janzen in Costa Rica  Ants (A) live in Acadia tree (t)  A & T have mutalistic relationship  A provides: protects and from leaf eating insects  T provides: o A live in thorns o A eat sugar from glands and at leaf base o A eat Beltian bodies (rich in fat) from leaf tip
Other interactions on the Ant-Acadia  Beetle protected with thick cuticle  2 wasp species protect each other (mutualism)  bird nest; ants attack for a while  monkey attacks bird nests (trees with no wasps)  monkey spreads plant seeds (trees with no wasps)
Mistletoe Butterfly  Lays eggs on mistletoe  Larvae eat M leaves  M is parasite of eulyptus  Mistletoe birds feed on M berries  Birds defecate M seeds ONTO eucalyptus branch  M seeds germinate on sucalyptus
ISOPTERA o T have many kinds of predators  Termites in Kenya o Men are the T mounds o Kenyans collect process and eat winged adult T o T are 40% fat and 40% protein o *********************  termites follow trail pheromone (TP) o TP is present in some pens
2-16-11  Ephemeroptera o Ephermera= short-lived o Ptera= wings o Common name: mayflies o Species= 2,000  Mayflies o 1. Incomplete metapmorphosis o 2. Eggs laid in water o nymphs breathe with gills o nymphs feed on plants o nymphs live 1-3 years o adults emerge at same time o adults do not feed o adults have 2 pair of wings o adults have 2 to 3 tails on abdomen o adults mate and die in 1 to 2 days  Taxonomy o Naming and arranging of species and groups into a system o Lumpers- have fewer orders/ categories o Splitters- have more orders o There are approximately 26 insect orders o Insect Identification:  “Keying” insects to order and family  1. Identify adult insects (not immature insects)  2. Use couplets or triplets
Mayflies  M Have good sense of timing  M Nymphs live 1-3 yrs  M adults live 1-2 days
Fisherpeople
Use lures that mimic insects present in the stream

Fisherpeople (F) use Mayflies (m) as lures:  M nymph has gills and tails  Emerging M adult is vulnerable  F match the M “hatch”  F observable behavior of fish
Use Aquatic Insects to monitor water quality:  If water is clean, there are many kinds of insects  Insects are sensitive to oxygen levels & water acidity 
Insects that can walk on water:
*** have extra surface wax  springtails have waxy plates on cuticle  Water measurer: waxy hairs on feet and legs  02/07/2011
Odonata: Damselflies & Dragonflies