Although early proponents of IPM emphasized ecological approaches to pest management, synthetic pesticides are still widely used in conventional agriculture. The “IPM Continuum” emphasizes a shift to biologically based strategies based on planning and knowledge of the crop ecosystem.
Diagram showing that organic or ecologically based pest management relies on cultural and vegetation management practices to make the crop less suitable for pest development (1st and 2nd phases). Release of biocontrol agents and application of less toxic insecticides are implemented if preventative strategies are not effective.
Examples of 1st phase cultural practices or strategies to reduce insect pest problems
Most of the certified organic crop acreage in the U.S. is located in the western states where conditions are less favorable for disease and insect pest problems.
It is important to know about the biology and behavior of key pests of crops grown on the farm. For example, all of the above pests disperse short distances and therefore can be managed using crop isolation/rotation.
An example: Tomatoes are susceptible to aphid transmitted viruses like cucumber mosaic virus. Late plantings should not be planted adjacent to early plantings to avoid spread.
Rotation with cover crops or with different market crops can be useful to break up disease and insect pest cycles. But some cover crops may suppress growth of market crops or can be hosts for secondary pests. Therefore when choosing cover crops be aware of potential secondary effects.
Biofumigation rotation crops like mustard and rape produce lots of foliage (high biomass). Plants are chopped and incorporated into the soil to release plant defense compounds (glucosinolates are converted by enzymatic action to isothiocyanates that can kill soil pathogens, insects, nematodes, etc).
Research by Larry Phelan with Ohio State University demonstrated that corn plants grown on organic soils supported lower numbers of ECB than plants on conventional soils. He hypothesized that nutrients and minerals in plants in organic soils were more balanced, thus were less suitable for insect pest development.
Additional research; lower numbers of Colorado potato beetle on potato grown in organic soil (manure) than in conventional soil (no manure).
Straw and plastic reflective mulch used an IPM tool. The straw mulch above helped reduce populations of Colorado potato beetle. The aluminum reflective mulch below helped reduce the incidence of aphid-transmitted viruses. However organic mulches may harbor other pests like squash bugs and planthoppesr.
Experiments conducted by Geoff Zehnder at Clemson University in South Carolina showed that a rye cover crop planted between rows of melon reduced the incidence of Watermelon Mosaic Virus. The cover crop made the melon plants less attractive to aphid vectors of the disease.
Conservation tillage may favor increased populations of predatory arthropods in the soil that can help control pest insects.
Some crop varieties have resistance or tolerance to certain pest insects. Examples include hairy-leaf cotton that can reduce whitefly infestations, and tight husk varieties of corn that reduce damage by corn earworm. While HPR has limited application for control of insect pests in conventional agriculture, it has more potential for use in organic farming because organic farmers can usually tolerate some insect pest damage and there are limited insecticide options.
The hairy spines or trichomes on ‘Prince Hairy’ potato negatively impact development of Colorado potato beetle.
Low level pest densities are tolerable in organic systems, thus partial or moderate host plant resistance is acceptable and even preferable in organic agriculture.
Learn more about ‘Habitat Enhancement’ or ‘Ecological Engineering’ to reduce insect pest problems in the above publication published in 2004 by CAB International.
Plant diversification enhances ‘top down’ action of natural enemies of pests. Called ‘top-down’ because the top animals in the system (predators) are affected, and they in turn prey on pest insects.
Permanent habitat for natural enemies at the Int’l. Organic Research Institute in Switzerland includes annual, perennial and woody plants that provide habitat to beneficial arthropods and vertebrates.
Examples of flowering plant strips established to attract and keep natural enemies (predators and parasites) of insect pests. The bottom photo shows flowering strips planted between rows of celery on a large farm in California.
This 2003 study indicated that highest rates of parasitism of cabbage worm occurred on cabbage planted closest to flowering strips, and that rates of parasitism decreased on cabbage planted further away from the flowering strips.
Planting flowering plants without knowledge of the specific predators/parasites that they attract has been called “chocolate box ecology”. This practice is generally not effective. The researcher or farmer must have knowledge of key pest and natural enemy biology and then screen insectary plants to identify those that enhance biological control.
Intercropping is the planting of different crop families in the same area. This helps to reduce disease and insect pest problems because it is more difficult for pests to develop in diverse plantings than in homogenous or mono-cropped plantings. Intercropping is based on the resource concentration hypothesis of Root (1973) which says that concentrated areas of host plants are easier for insect pests to colonize. Intercropping interferes with pests in a ‘bottom-up’ manner because the influence is exerted on the pest, or the lower animal in the system.
Trap crops are crops that are more attractive to the pest than the main crop. They are usually planted in borders around the main crop or may be also be planted in strips within the main crop.
Most success with release of biological control agents for control of insect pests has occurred in greenhouse systems.
Predatory mite (left) and Orius (minute plant bug) are commonly used predators released in greenhouses to control insect pests (top). Bottom: Systems to deliver predatory insects on greenhouse plants.
These examples of biological control failures in field-grown organic crops occurred because of incompatible life histories, or because of interference by other natural enemies.
Bacillus thuringiensis is one of the most commonly used and effective microbial biological control agents. Several varieties are commercially available for control of different pests.
Codling moth granulosis virus products are widely used in Europe, but not widely used in the U.S. (some in sustainable/organic tree fruit production)
Efficacy of these products depends on favorable environmental conditions, and the products are expensive.
Some synthetically produced pheromones are approved for use in organic farming systems.
Trends in use of OMRI-approved insecticides. Use of broad spectrum materials like pyrethrin is decreasing because of negative effects on natural enemies (non-target effects). Use of neem-based products is increasing because of effectiveness against different pests and generally low toxicity against beneficial arthropods. Spinosad is highly effective against different insect pests, but has toxicity against beneficials and is expensive.
The efficacy of some OMRI-approved insecticides can be enhanced with specialized application equipment.
In this organic tree fruit system a flowering strip is planted to attract an egg parasite of the brown apple moth.
Attract and Kill products mix a pheromone to attract the insect pest along with an insecticide to kill the pest. These are currently used in conventional production but products using OMRI-approved insecticides could be developed for organic systems.
In an Attract and Reward system, beneficial insects are attracted into the crop by application of a volatile organic compound or lure. They are kept in the area by plantings of flowering plants that provide pollen and nectar. Thus the beneficial insects are rewarded and the level of pest control is enhanced.
We are just now beginning to place economic value on ecosystem services (biological control from natural enemies is an ecosystem service).
A New Zealand study to quantify the value of insect predators on conventional and organic farms
Mortality of aphids by ground dwelling predators (beetles, spiders, etc) was much greater on organic than on conventional farms.
The dollar value of ground dwelling predators like ground beetles, spiders and earwigs ranged as high as $200 per hectare per year (mostly from savings in insecticide costs).
Integrated Pest Managment
Planning an Insect Pest Management
System from the Ground Up
(with examples from organic research)
Research Institute of Organic Agriculture, FiBL, Switzerland
Geoff Zehnder, Sustainable Agriculture
Program, Clemson University
Integrated Pest Management
Integrated pest management (IPM) is a pest control strategy that
uses a variety of complementary strategies including: biological
and cultural management, mechanical and physical controls, and
genetic and pesticides when needed (source: Wikipedia).
Interesting fact: For their leadership in
developing and spreading IPM worldwide,
Dr. Perry Adkisson (Texas A&M) and Dr.
Ray Smith (UC Berkeley) received the
1997 World Food Prize.
Integrated Pest Management
Concept developed in the 1950s
Early proponents emphasized ecological
approaches for more permanent solutions
Reactive approaches dominate
Pesticides are relatively cheap (ecological
and societal costs not factored)
“IPM Continuum” culminates in biologically
Organic Pest Management:
Emphasizes Preventative Practices
(Foundation of Organic Pest Management)
implemented in the
initial stages of
organic farm planning
Prevent and avoid
Have roots in
Make crop unavailable to
pests in space/time
Site selection, crop isolation,
timing of planting/harvest,
Make crop unacceptable to
Intercropping, trap cropping,
Reduce pest survival by
enhancing natural enemies
Increase crop ecosystem
Alter crop susceptibility to
Farm Site Selection
Pest management not usually most
important consideration, but
Many organic farms are located in regions
where climate is unfavorable for pest
Example: plum curculio
In general, higher, cooler
and dryer regions support
fewer insect pests
Most effective against pests that
disperse short distances and/or that
overwinter near host crop fields.
Carrot fly Colorado potato
beetle Onion maggot
Learn about key pest (insect and disease) host range
and biology/behavior to help with crop rotation plan
indicate that woody
field borders influence
insect pest populations:
Habitat for natural
Can inhibit movement
of pests into fields
Isolation of Susceptible Crops
In Space or Time
Depending on the
virus/vector, new crops
should be isolated
from sources of
fields, weed hosts, etc)
Rotation with Cover Crops
Beneficial, but be aware of secondary
Allelopathy; may suppress crop growth
Examples; barley, oat, wheat, rye, canola,
May harbor secondary pests
i.e. wireworms attracted to grass cover crops
Rotation with Biofumigation Crops
Brassica crops (mustards,
Plant defense compounds
Soil concentrations high
enough to kill pathogens,
weed seeds, soil insects
Soil Quality Management
Does it affect above-ground pest damage?
Organic farming proponents have long
held the view that the likelihood of pest
outbreaks is reduced in “healthy soil”
Sir Albert Howard. 1940.
RC Oelhaf. 1978
MC Merrill. 1983
•Belowground and aboveground habitat
management is equally important
•Plant resistance is linked to optimal physical,
chemical and biological properties of soil
Miguel Altieri (UC Berkeley)
European Corn Borer Infestation Reduced on
Plants Grown in Organic Soils
Compared egg-laying on plants
grown in soil from organic vs
Significantly more ECB eggs
laid on plants in conventional
Egg-laying was more variable
on plants in conventional soils.
Variability in egg-laying affected
by plant mineral balance
Hypothesis: biological buffering
in org. soils
Research by Dr. Larry Phelan;
Ohio State University
Reduced development of Colorado potato
beetle on potato grown in organic soil
Research by Alyokhin &
Mulch: an IPM tool
Can help reduce
Colorado potato beetle
Aphid and thrips
May exacerbate some
Cover crop as camouflage
Annual rye planted
between rows in late
Virus incidence lower
in cover crop
Reflective mulch also
% Plants Infected with WMV
Favors rich soil biota
and diversity of soil
numbers of predatory
Host Plant Resistance
Resistance vs. Tolerance
Limited application for
control of insect pests in
Efficacy of synthetic
Low tolerance for cosmetic
Partial plant resistance not
Whitefly Damage: Hairy
vs. Smooth Leaf Cotton
Can’t easily penetrate tight husk varietie
`Prince Hairy’ Potato
From Cornell Breeding Program
Moderate HPR is preferable in
Low-level pest densities
support natural enemy
Manipulate planting and
harvest dates for
Demand may provide
commercial incentives for
seed companies to
Second Phase Strategies
Make habitat less suitable
for pests; attractive to
Provides food and shelter
for natural enemies
(predators and parasites)
Alternative hosts or prey
Supply of nectar and pollen
action of natural enemies
Island Habitats on Farms
raised strips across fields
Primarily used in large
fields (cereal, row crops)
Winter home for > 1000
per square meter
(Thomas et al. 1992)
Mixture of forbs and
bank” and “insectary
Increases rates of
Management of weed
strips can be used in
Int’l. Organic Research Institute in Switzerland
Flowering Insectary Strips
Provides pollen and
Attracts and keeps
natural enemies in
Evaluation of Wildflower Strips to
Enhance Biocontrol in Cabbage
Pfiffner et al. 2003
Strips 10-90 meters
Cabbage with no strips
Higher rate of parasitism
next to strips
Parasitism increased with
proximity to strips
Scale/size of strips
relative to crops important
Flowering plants added
without prior testing
Parasitic wasps visit an
ave. of only 2.9 plant
Researchers now screen
plants for optimal species
Farmers collect info on
key pests, natural
enemies to design
of host plants are
easier for insect pests
to find and colonize
Interferes with pests
in a `bottom-up’
relative size in the
landscape are key factors
Blue Hubbard around
Pumpkins around melons
Cherry peppers around bell
pepper (pepper maggot)
Collards around cabbage
Top; Sam Pair, USDA-ARS, Lane,
Third Phase Strategies
Release of Biological Control Agents
Allow for rapid
response to pest
Most research in
Release of Biocontrol Agents in
Field-Grown Organic Crops
caterpillars in vegetables, aphids in wheat,
leafhopper in vineyards
Mite, ladybug and lacewing predators
spider mites, aphids and leafhoppers in
vineyards and apple orchards
Release of Biocontrol Agents in
Field-Grown Organic Crops
Cherry fruit fly
on sweet cherry
Incompatible life histories of pest and biocontrol agent, or disruption
of agents by other natural enemies
1901; Silkworm “sudden
1911: Named by Ernst
Farmer use in 1920s
EPA registration in 1961
Thousands of strains
active against caterpillars,
Toxin attacks gut cells Bt spore crystals; Courtesy of Rosemary
Walsh, EMF-LSC, Penn State
Codling Moth Granulosis Virus
Isolated from codling
moth in 1963
1979: Apple Biological
formulations; little use
Of Less Importance
Entomopathogenic Fungi and Nematodes
Why is Use of Biological
Control Agents Limited?
Commercial development restricted only to
those with potential market for large acreage
Many effective agents for less important pests
never pass beyond developmental stage
Mass rearing techniques
Small companies; limited technology
Suboptimal quality in past but improving
But used regularly in organic farming
Research needed on how to integrate use of
biocontrol agents with other strategies
4th Phase Strategies
Insecticides of biological, mineral origin
Mineral oils, insecticidal soaps
Non-synthetic origin (except
Organic Insect Control
Current Trends in Organic Farming
Reduced pyrethrin use; non-target effects
Azadirachtin (neem) use is increasing
Successful experiments against several pests
including aphids and some chewing insects
Spinosad one of few new approved materials
Fermentation product of bacterium
Successfully tested worldwide against a variety of
Quassia Extract (bitter wood)
Many active compunds;
alkaloids, triterpenes and
bitter principles (quassin)
50X more bitter than
quinine; herbal remedy
Used mostly in Europe:
To control aphids in cereal
To control wooly apple
aphid in tree fruit
Used as a repellent;
of insect pests
Most use in tree fruit,
Dropleg application of Bacillus thuringiensis var. kurstaki
against lepidopterans in leek. The application from top and
bottom increases efficacy of Bt applications.
Photo: Eric Wyss, FiBL
Limits of OMRI-Approved
Degrade quickly; low potency; short
Must integrate with other strategies
More research needed
Develop treatment thresholds for organic
systems where natural enemies are
EPA; fast-track registration
Limited by markets
Organic Insect Pest Management:
Integration of tactics; i.e. 2nd
Pest: Brown apple
by nectar plants
Attract & Kill
Products mix pest
Attract & Reward
Lures with synthetic plant volatiles
Attract beneficial insects
Pollen, nectar plants
Enhance level of pest control
Valuing Ecosystem Services
“Ecosystem services are the conditions
and processes through which natural
ecosystems, and the species that make
them up, sustain and fulfill human life
The value of global Ecosystem Services
estimated at $33 trillion (Costanza et al., 1997).
Dr. H.S. Sandhu
Lincoln University, New Zealand
1. Assessing the predation rate of aphids (Acyrthosiphon
2. Assessing the predation rates of blow fly eggs
(Calliphora vicina R.D.) simulating carrot rust fly eggs
(Psila rosae Fab.)
Experimental assessment of ES in arable fields
29 Study Sites (14 Organic and 15 Conventional fields)
Fig. (a) Map of New Zealand study area (Canterbury).
(b) Location of selected arable organic ( ) and conventional fields ( )
Predation rates of aphids and fly eggs in
selected arable fields
Fig. Predation rates (%removal/24h) of aphids
and fly eggs in selected fields
Ground living polyphagous predators:
Are they any value?
Dollar value of biological control of aphids in selected organic fields
More information on insect management for
organic farms can be found at:
This presentation address general organic production practices. It is to be
to use in planning and conducting organic horticulture trainings. The
presentation is part of project funded by a Southern SARE PDP titled
“Building Organic Agriculture Extension Training Capacity in the
•Elena Garcia, University of Arkansas CES
Heather Friedrich, University of Arkansas
Obadiah Njue, University of Arkansas at Pine Bluff
Jeanine Davis, North Carolina State University
Geoff Zehnder, Clemson University
Charles Mitchell, Auburn University
Rufina Ward, Alabama A&M University
Ken Ward, Alabama A&M University
Karen Wynne, Alabama Sustainable Agriculture Network