please read carefully ..
Pest Control Part 3
Biology 140 Instructor: Dr. Franklin Quarcoo
Office Location: 115 Henderson Hall Phone: 727-8792
Office Hours: MWF 3.00 – 5.00 pm Email: quarcoof@mytu.tuskegee.edu
Pest Control -- Outline
• Pests (in Part 1) • Pesticides (in Part 1)
– Benefits (in Part 1) – Problems (In Parts 1 & 2) – Categories (In Part 2) – Chemical types (In Part 2) – Regulation of Pesticides
• Alternatives to Pesticides • Reducing Pesticide Exposure
Regulation of Pesticides • Pesticides regulated by EPA, USDA, and FDA (Food and Drug
Administration) • Laws regulating pesticides:
– Federal Food, Drug, and Cosmetic Act (FFDCA). • Allows EPA to set limits for the amount of pesticides that remain in
food. – Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA).
• Requires registration and licensing of all pesticide products with EPA.
– Food Quality Protection Act (FQPA) -- 1996. • Amended both FFDCA and FIFRA. • Cost-benefit analysis replaced hard standards for approving or
banning pesticides. • More protection for children.
Alternatives to Pesticides -- Outline
• Cultivation practices. • Biological control -- natural enemies. • Genetic control:
– Conventional genetics. – Biotechnology.
• Hormonal control. • Integrated Pest Management (IPM)..
Cultivation Practices • Burning or plowing under crop residues.
– Disrupts insect life cycles. • Crop rotation -- changing crops each year.
– Different crops have different pests. – Prevents long-term build-up of pest populations. – e.g. Tomato wilt (fungus) -- once it strikes, spores
remain in soil and infect new plants next year. • Maintaining strips of natural vegetation between
strips of crops (e.g. British Isles). – Maintains populations of natural enemies of pests in
uncultivated strips. • Vacuuming insects off of crops (“salad vac”)..
Salad Vac Removing Insect Pests
Cultivation Practices
• Planting trap crops: – Small area of same/different plant as main crop. – Planted 1-2 weeks earlier than main crop. – Serves as magnet for pests. – Spray trap crop heavily; few survivors. – Destroy trap crop (not harvested).
Cultivation Practices
• Elimination of alternative hosts. – Some pests require two hosts to complete life
cycle. – Removal of the non-crop host breaks the life
cycle. – Example:
• Wheat rust alternates between wheat and barberry (introduced shrub).
• 1918-1981 -- U.S. government campaign to eradicate barberry from wheat-producing regions greatly reduced wheat rust outbreaks.. ICA
Question
• Which cultivation technique helps maintain natural enemies of farm pests?
• (a) Crop rotation • (b) Elimination of alternative hosts • (c) Strips of natural vegetation next to field • (d) Trap crops • (e) Vacuuming pests off of crops
Answer
• Which cultivation technique helps maintain natural enemies of farm pests?
• (a) Crop rotation • (b) Elimination of alternative hosts • (c) Strips of natural vegetation next to field • (d) Trap crops • (e) Vacuuming pests off of crops
Biological Control • Many pests are imported species. • Natural enemies were not imported with the
pest. • Natural enemies can be located and imported,
BUT… – Natural enemies must be tested first to see if they will
attack other, desirable, native species in their new range.
• USDA has released 1000 insects to control pests. – Most results favorable.
• Worldwide, more than 30 weed species are now controlled by introduced insects..
Biological Control- Successful Examples
• Cactus moth -- introduced to control prickly pear cactus in Australia.
• Brazilian weevils -- introduced to control water hyacinth (introduced plant that covers lakes) in Africa.
• Fungus spores -- sprayed to control swarming locusts in Africa.
• Rabbits in Australia -- now controlled by an introduced infectious virus.
• Ladybug beetles -- commonly used to control pests in gardens and greenhouses..
Cactus-Eating Moth Controls Prickly Pear Cactus in Australia
Before Cactus Moths After Cactus Moths
Ladybug Control of Cottony Cushion Scale in Orange Groves
Parasitic Wasp Control of Tobacco Hornworm
Wasp cocoons
Parasitoid Wasp Control of Mealybug
Biological Control- Problem Cases
• 16% of 313 parasitoid wasp species introduced by USDA have attacked native species.
• Cactus moth (introduced into a Caribbean island) has invaded the U.S. and now threatens native cacti in western U.S..
Conventional Genetic Control: Selective Breeding
• Many crops are selectively bred for resistance to pests.
• Potato and late blight (fungus): – 1845-1847 -- Ireland -- potatoes devastated by blight. – One million starved; one million emigrated. – Potato varieties developed that are resistant to blight.
• Wheat and Hessian fly: – Hessian fly introduced to U.S. by Revolutionary soldiers
(Hessians). – Hessian fly devastated wheat. – Wheat varieties developed that produce a chemical
that kills fly larvae when they feed on wheat leaves..
Conventional Genetic Control: Sterile Males
• Some female insects mate only once, lay eggs, then die. • Males are raised in lab; irradiated to make sterile. • Sterile males are released into natural populations in large
numbers. • Most wild females mate with sterile males; fail to
reproduce. • Developed to control screwworm fly in 1950s.
– Screwworm fly lays eggs in open wounds of cattle. – Leads to infections that cause death. – Devastated cattle industry in south in 1940s.
• Screwworm fly eradicated in U.S. in 1982 and in several Central American countries in 1994-1996.
• Sterile males now being used to control tsetse fly in Africa..
Conventional Genetic Control: Limitations
• Pests continue to evolve and develop ways to overcome crop resistance. – Wheat and Hessian fly -- new varieties required
seven times. • Sterile male technique only works on
certain species.
Pest Control through Biotechnology • Biotechnology -- introduce genes from other
organisms into crops. • New crops called transgenic or genetically
modified organisms (GMO). • Transgenic crops:
– 60 approved. – 220 million acres planted worldwide. – Most important: soybeans, corn, cotton.
• Some transgenic crops have greater resistance to pests; require less pesticide..
Pest Control through Biotechnology: Bt Crops
• Bt (Bacillus thuringiensis) -- a bacterium that produces a protein that kills some common plant- eating insects.
• Protein is harmless to mammals, birds and most other insects.
• Bt gene has been put into a number of crops -- esp. cotton, potatoes, corn.
• In 2004, 32% of corn and 46% of cotton acreage in U.S. was planted with Bt varieties.
• Benefits: reduced pesticide use, greater food production..
Bt Gene Protects Potatoes from Colorado Potato Beetle
Bt PotatoesNon-EngineeredPotatoes Non-Engineered
Potatoes
Pest Control through Biotechnology: Roundup Ready Crops
• Roundup -- an herbicide that kills all plants; non- toxic to all animals.
• Genes for resistance to Roundup have been introduced into cotton, soybean and corn.
• Farmers plant roundup resistant (“Roundup Ready”) varieties.
• Then spray once with Roundup to kill all weeds (but not crop).
• Uses less herbicide than traditional method of repeated applications of more specific herbicides.
• 90% of U.S. soybean crop is Roundup Ready..
Pest Control through Biotechnology: Potential Problems
• Costly seeds -- poorly suited for developing countries.
• Pests likely to develop resistance to transgenic defenses (like Bt protein).
• Resistant genes from transgenic crops may be shared with close relatives (weeds), leading to “Superweeds” that are resistant to herbicides. – A few weeds have become “Roundup ready”.
ICA
Question • Round-up ready soybeans:
• (a) Are not affected by Round-up • (b) Are not affected by the Bacillus thuringiensis
(Bt) bacterium • (c) Contain a gene that causes them to make
Round-up • (d) Produce a chemical that kills weeds growing
nearby • (e) Contain the Bt gene
Answer • Round-up ready soybeans:
• (a) Are not affected by Round-up • (b) Are not affected by the Bacillus thuringiensis
(Bt) bacterium • (c) Contain a gene that causes them to make
Round-up • (d) Produce a chemical that kills weeds growing
nearby • (e) Contain the Bt gene
Hormonal Control: Pheromones • Pheromones -- chemicals secreted by one
individual of a species to influence the behavior of other individuals of the same species. – e.g. ant trail pheromones. – e.g. mating pheromones -- secreted to attract mates.
• Pest control by pheromones: – Trapping technique -- pheromones in traps used to
capture pests or lure them into eating poisonous bait. – Confusion technique -- spray field with pheromone;
males can’t locate females; no mating. • Natural chemicals -- totally safe for crop and non-
target species. • Used on boll weevil (affects cotton), codling moth
(affects pears and apples), Japanese beetles.
Japanese Beetle Pheremone Trap
Hormonal Control: Juvenile Hormone
• Juvenile hormone -- decrease triggers pupation in insect caterpillars (larvae).
• Spray juvenile hormone on caterpillars, pupation does not occur.
• Caterpillar keeps feeding; grows overly large; dies.
• Caterpillar never becomes adult; never reproduces..
Hormonal Control: Ecdysone • Ecdysone -- triggers molting in insect
larvae. • Insecticide based on ecdysone = Mimic. • Mimic causes moth and butterfly larvae
(caterpillars) to start molting, but then stop.
• Larva is trapped in old skin; starves to death.
• Used on gypsy moth (introduced moth of northeastern U.S. forests)..
Hormonal Control: Drawbacks • Pheromones are species-specific.
– Each pest requires its own pheromone pesticide.
– Costly and time-consuming to develop. • Juvenile hormone and Mimic only work on
certain groups of insects.
ICA
Question
• Juvenile Hormone is used to:
• (a) Lure male insects into poisoned traps • (b) Prevent insect larvae from molting
completely. • (c) Prevent insect larvae from pupating. • (d) Prevent male insects from locating
females.
Answer
• Juvenile Hormone is used to:
• (a) Lure male insects into poisoned traps • (b) Prevent insect larvae from molting
completely. • (c) Prevent insect larvae from pupating. • (d) Prevent male insects from locating
females.
Integrated Pest Management (IPM) • Integrated Pest Management (IPM)
combines a variety of pest control techniques.
• Goals of IPM: – Minimize (not eliminate) use of synthetic
pesticides without jeopardizing crops. – Maintain pest populations below economic
threshold (not totally eradicate) – Economic threshold = point at which the
economic loss to pest damage exceeds the cost of pesticide application..
Integrated Pest Management (IPM) • Components of IPM:
– Set action thresholds -- points at which pest populations indicate that action is needed (economic threshold).
– Monitor and identify pests. – Prevention -- Use cultivation, biological, genetic and
hormonal controls as appropriate. – Control -- Use pesticides (brands and quantities) that
do the least damage to the natural enemies of the pests, and to the environment.
• Massachusetts apple farmers who used IPM: – Cut pesticide use by 43%. – Maintained yields equal to conventional farmers..
IPM in Indonesia • Indonesia depends on rice. • Pesticides used heavily to control brown
planthopper (up to 3 times a week). • Planthoppers developed resistance to almost
every insecticide. • 1986: Conversion to IPM.
– 56 of 57 pesticides banned. – Program to educate farmers about IPM.
• 1987-1992: IPM program a success. – Pesticide use cut by 65%. – Rice production rose by 15%..
Pesticide Use and Rice Production in Indonesia
IPM Started
Reducing Pesticide Exposure: Food • Wash fruits and vegetables.
– Reduces (does not eliminate) pesticide residues. • Choose fruits and vegetable that are low in pesticide
residues (see next slide). • Tolerate minor blemishes on fruits and vegetables. • Choose organic foods.
– “Organic” now defined by law: • No conventional pesticides or chemical fertilizers. • No antibiotics or growth hormones (livestock). • No genetically-engineered foods. • No irradiated foods. • No fertilization with sewage sludge.
– Usually more expensive..
Aquatic Ecosystems
Reducing Pesticide Exposure: Lawns and Gardens
• Mow grass no shorter than 3 inches. – Reduces weeds through competition.
• Allow a diversity of plants in lawn – Don’t try and kill every “weed”.
• Eliminate plants that attract pests (roses). • Grow plants that naturally repel pests (marigolds,
chrysanthemums, basil, peppermint, garlic). • Maintain hedgerows and fencerows of natural
vegetation. – Habitat for natural predators.
• Buy and release ladybug (ladybird) beetles. – Natural predators..
Reducing Pesticide Exposure: Homes • Install or repair screens to keep out insects. • Caulk around windows, doors, plumbing
entry points, etc. to keep out roaches, ants, mice, etc..
• Identify ant entry points; sprinkle with ground cinnamon.
• Drain stagnant water (buckets. etc.) where mosquitoes might breed.
Reducing Pesticide Exposure: Homes • Keep food in sealed containers. • Put few bay leaves in containers of flour to
discourage flour weevils. • Clean spilled food and take out garbage regularly. • Use flypaper to catch flies (instead of bug sprays). • Tolerate spiders (insect predators). • Remove aphids, scales, mites from house plants
by: – Washing stems and leaves with rubbing alcohol, or – Spraying plants with dilute solution of dish soap and
water..
Reducing Pesticide Exposure: General • Buy the pesticide that is appropriate for the pest and
situation that you want to control -- Read the label before you buy.
• Use the pesticide only as directed -- Read the label before you use.
• Use only the minimum amount of pesticide to get the job done -- Read the label.
• Use eye protection and a respirator, if suggested -- Read the label.
• When applying the pesticide, be aware of how children and pets might come in contact with the treated area.
• Wash your hands (or other exposed skin) after contact with pesticides.
END