PESTS AND PEST CONTROL VOCABULARY Pest any organism

PESTS AND PEST CONTROL

VOCABULARY Pest: any organism that is noxious, destructive, or troublesome Agricultural pests Insecticide – toxin aimed at killing insects Herbicide – toxin aimed at killing plant or fungus Pesticide – toxin aimed at killing all pests

DDT: PART 1 1940 S – 1950 S General Consensus at the time: Toxic to insects and NOT to humans Broad spectrum, kills all types of insects, but relatively low risk to mammals Persistent (sticks around without degradation) Saved many lives during WWII to prevent spread of body lice and death from typhus fever (sores, ab pain, deliria); also used in tropics to stop the spread of malaria by mosquitoes Used to increase crop production by controlling insect pests in agriculture

DDT PART 1 (CONTINUED) History of DDT: DDT (dichlorodiphenyltrichloroethane) is one of the most wellknown synthetic pesticides 1874 - synthesized 1939 - DDT's insecticidal properties discovered, where it kills by opening sodium ion channels in the neurons, causing them to fire spontaneously leading to spasms and eventual death used with great success in the second half of World War II to control malaria and typhus among civilians and troops after the war, DDT was made available for use as an agricultural insecticide, and soon its production and use skyrocketed. 1948 - Swiss chemist Paul Hermann Müller was awarded the Nobel Prize in Physiology or Medicine "for his discovery of the high efficiency of DDT as a contact poison against several arthropods. “

DDT: PART 2 Decline of birds on top of food chain (osprey, eagles) Eggs breaking before hatched Bioaccumulation: synthetic organics and breakdown products trapped in body’s lipids Biomagnification: multiplying affect of bioaccumulation as you move up food chain, negative in this case Pg. 423

DDT PART 2 (CONTINUED) 1960 S - TODAY • 1962, Silent Spring by American biologist Rachel Carson was published, cataloguing the environmental impacts of the indiscriminate spraying of DDT in the US and questioned the logic of releasing large amounts of chemicals into the environment without fully understanding their effects on ecology or human health. • The book suggested that DDT and other pesticides may cause cancer and that their agricultural use was a threat to wildlife, particularly birds. • Its publication was one of the signature events in the birth of the environmental movement, and resulted in a large public outcry that eventually led to DDT being banned in the US in 1972. • DDT was subsequently banned for agricultural use worldwide under the Stockholm Convention, but its limited use in disease vector control (like malaria) continues to this day and remains controversial. • the US ban on DDT (and Endangerd Species Act of 1973) is cited by scientists as a major factor in the comeback of the bald eagle from near-extinction in the contiguous US.

Environmental Effects of Chemical Pesticides Toxicity through biomagnification up food chain Broad effect on unintended organisms (like us) Location of application (in a riparian environmental, a watershed or upwind) Effect on beneficial insects Persistent: take a long time to break down – esp. chlorinated hydrocarbons, long-range danger and long term

NONPERSISTENT PESTICIDES Since persisent pesticides are banned now, Agrochemical industry has created nonpersistent organic phosphates (malathion, parathion, chlorpyrifos) and carbamates (aldicarb and carbaryl) Typically inhibit enzyme cholinesterase essential for proper functioning of nervous system in insects, and all animals (us too) Dangers: Persistent enough to ride the food supply from farmer to consumer (few weeks to break down) Many are more “toxic” to mammals than older chlorinated hydrocarbons varieties like DDT (higher LD 50) and require more applications (higher dosage)

4 CATEGORIES OF NATURAL OR BIOLOGICALPEST CONTROL 1. Cultural: nonchemical alteration of environmental factors (import restrictions, grass lawn of at least 3 inches high keeps away most crabgrass & noxious weeds, crop rotation) 2. Control by natural enemies/predators (parasitic wasp uses gypsy moth pupa or tomato hornworms, or less pesticide spraying to allow natural return predators to control brown planthoppers on rice) 3. Genetic Control: Chemical Barriers (crossbreeding of plants to enhance toxic chemical production by plant like with Hessian fly and wheat leaves) Physical Barriers (hooked sticky hairs on stems to trap small larva)

4 CATEGORIES OF NATURAL OR BIOLOGICALPEST CONTROL 3. Genetic Control (cont. ): Sterile Males so no successful offspring Biotechnology to introduce genes from bacteria, virus or other plant species (GMO’s like engineering Bt, a bacillus thuringienis protein, into plants which kills larva of plant eating insects, but harmless to mammals & birds) (Roundup herbicide resistant gene in crops, 90% of US soybean crop is “Roundup Ready”) 4. Natural Chemical Controls Use of hormones (chemical signals) like pheromones to cause physiological issues or stunt development cycle (Juvenile hormone prevents pupation, or Mimic emulates ecdysone hormone causing molting to begin but not finish

CONCERNS WHEN REGULATING PESTICIDE Evaluated for intended use and impacts on environmental health Proper training and safety of agricultural workers using it Risk of pesticide residue on our food

DDT was not used for handling weeds but has saved millions of lives by controlling disease-causing pests The 1948 Nobel prize was awarded to Paul Muller for discovering DDT is a cheap, persistent, synthetic, organic, compound & is subject to biomagnifications in food chains

DISEASES Lyme disease can be transferred to humans through a bite from an infected tick (vector) Mosquitoes are the vector for Malaria The protozoan of the genus Plasmodium is the causative agent of malaria DDT is great at killing mosquitoes… should we use it? Lack of access to safe drinking water is a major cause of disease transmission in developing countries.