Wildlife and Ecology
Course Title:
Credit Hours 3(c2-2)
Department of
Wildlife and Ecology
Integrated Pest Management:
Integrated Pest Management (IPM) is an ecosystem approach to
crop production and protection that combines different management strategies
and practices to grow healthy crops and minimize the use of pesticides. Or
IPM is an approach-based method for analysis of the
agro-ecosystem and the management of its different elements to control pest and
keep them at an acceptable level (action threshold) with respect to the
economic, health and environmental requirements.
Several kinds of pests can infest the different parts of
plants/crops, and damage them partially or sometimes completely, seriously
affecting the quantity and quality of the yield. Moreover, certain crop
production intensification practices (e.g. early season spraying of pesticides
in rice fields) can even increase the impact of pests on plants. In order to
protect their plants, farmers used to spray chemical products (pesticides).
However, these chemicals could have a negative effect on and cause serious
damage to health and the environment as well as, sometimes, on to the health of
the plant itself.
IPM includes the necessary Phytosanitary measures, monitoring
and diagnostic system, good agricultural practices and the management of
natural enemies with the minimum amount of pesticides (when needed and of good
quality). IPM is thus an important part of Integrated Plant Production
Management (IPPM) and sustainable crop production intensification. By
enhancing the ecosystem function, by making the agricultural ecosystem
healthier, more ecosystem services are provided: in this case, pest control.
How to practice Integrated Pest Management?
v Good agricultural
practices in plant protection
One of
the biggest problems with many of the developments in IPM over the years has
been the tendency to generalize and make recommendations for farmers across
large and highly heterogeneous areas. This has been true for all manner of
input recommendations including fertilizers, pesticides and crop varieties.
This problem, ecological heterogeneity, has also severely limited the
effectiveness of government monitoring and forecasting systems. All of these
practical issues vary on a small spatial scale. This local specificity requires
that farmers become IPM experts. The recommendations or decision criteria of
each approach reveal a steady progression in the accommodation of ecological
heterogeneity and farmer control of agro-ecosystem management. Maintenance of
crop health is essential for successful farming for both yield and quality of
produce. This requires long-term strategies for the minimization of pest
and disease occurrence preferably by enhancing natural control mechanisms,
growing a “healthy crop”. Specific measures include the use of disease- and
pest-resistant crops, rotation of crops, including those with pasture, to
provide disease breaks for susceptible crops, apply non-chemical control
practices (thermic, mechanical) as applicable and as last resort the tactical
use of agrochemicals to control weeds, pests, and diseases following the
principles of IPM and guidelines of good application practices. Any
measure for crop protection but particularly those involving substances that
are harmful for humans or the environment has to be carried out with state-of-the-art
knowledge and equipment. Integrated Pest Management should focus on the
following points:
·
Use resistant cultivars and varieties, crop
sequences, associations, and cultural practices that minimize the pressure and
maximize biological prevention of pests and diseases.
·
Maintain regular and quantitative assessment of
the balance status between pest and disease and beneficial organisms of all
crops.
·
Apply pest and disease forecasting techniques
where available.
·
Understand and use non-chemical pest and
disease management practices.
·
Decide on interventions following consideration
of all possible methods and their short- and long-term effects on farm
productivity and environmental implications in order to minimize the use of
agrochemicals, in particular promote integrated pest management (IPM).
·
Store and use agrochemicals according to legal
requirements, e.g. registration for individual crops, rates, timings, and
pre-harvest intervals.
·
Assure that agrochemicals are only applied by
specially trained knowledgeable persons.
·
Assure that equipment used for the handling and
application of agrochemicals complies with established safety and maintenance
standards.
·
Maintain accurate records of agrochemical use.
·
Avoid any point source pollution from
agrochemicals resulting from use, storage, cleaning and disposal of products or
application equipment.
·
Avoid impact on non-target areas of any pest
and disease management activity.
IPM strategies are different for each crop, for a country,
for a region, even for one location, depending on local varieties used, local
agronomic practices and various crop protection options available. IPM can
never be delivered in a “package”; it needs to be developed, adapted and
tailor-made to fit local requirements. Designing and practicing effective IPM
systems is about learning and continuously finding solutions to changing field
situations and problems.
v Prevention and
suppression of harmful organisms
Crop rotation;
inter-cropping
If you plan to
grow the same crops regularly, you will need to rotate them. Different crops need
particular nutrients in the soil and use these up at a particular level in the
ground. At the same time, each kind of plant attracts its own particular pests
and diseases, which soon become established around the crop. If you grow the
same kind of crop in the same place season after season, the nutrients that the
plant needs are quickly exhausted, the plants grow weak and stunted and quickly
come under attack from waiting pests and diseases. Crop rotation is important
if the rotation reduces inoculum. Crop rotations should be observed since there
are many pathogens that survive on numerous types of both living and dead plant
materials. Some crops, such as sorghum, pearl millet and maize, may drastically
suppress weed population and reduce its biomass. Pearl millet may exhibit
residual weed suppression in the following crop. It is obviously necessary to
evaluate which rotations can be grown successfully in the agro-ecological zone
to maximize yield and pest control.
Use of adequate
cultivation techniques
Burning plant
residues and ploughing the soil is traditionally considered necessary for
phytosanitary reasons: to control pests, diseases and weeds. In a system with
reduced mechanical tillage based on mulch cover and biological tillage,
alternatives have to be developed to control pests and weeds and Integrated
Pest Management becomes mandatory. One important element to achieve this is
crop rotation to reduce the pest-risks associated with monocultures,
interrupting the infection chain between subsequent crops (different sowing
dates and distances between fields with the same crops) and making full use of
the physical and chemical interactions between different plant species.
Synthetic chemical pesticides, particularly herbicides are, in the first years,
inevitable but have to be used with great care to reduce the negative impacts
on soil life. To the extent that a new balance between the organisms of the
farm-ecosystem, pests and beneficial organisms, crops and weeds, becomes
established and the farmer learns to manage the cropping system, the use of
synthetic pesticides and mineral fertilizer tends to decline to a level below
that of the original "conventional" farming system.
Where
appropriate, use of pest resistant/tolerant cultivars and standard/certified
seed and planting material
Plant breeding
has resulted in the development of a large number of varieties that are
resistant to several kinds of diseases. Breeding is based on access to plant
genetic resources, which can be conserved in the field and in gene-banks. Wild
cultivars have low economic benefits in most cases, but often show resistance
to locally occurring biotic and abiotic stresses; and cross-breeding of these
varieties can result in the development of varieties that can perform better, by
out-competing weeds, without the application of large doses of pesticides. A
sustainable seed system will ensure that high quality seeds of a wide range of
varieties and crops are produced and fully available in time and affordable to
farmers and other stakeholders. Access to certified seeds will improve the
uptake of farmers of higher-yielding varieties which can withstand stress and
thus decrease environmental problems that are caused by use of pesticides.
Diseases:
Control or Management?
Coping with
plant diseases in the field is relatively difficult because the causal
organisms (bacteria, fungi, virus and nematodes) are very small and cannot be
seen moving around like insects or rats. The most important first step in
thinking about diseases is to realize that diseases must be managed not
controlled. What is the difference? Management means a complete set of
activities that support each other. Management means that these activities are
carefully planned and are implemented over several seasons, not controlled
within a single season. Management included control methods for prevention, and
control methods to slow down epidemics; diseases will never be completely
eradicated - only populations reduced to very low levels. Management usually
needs the cooperation of several farmers working together to reduce overall
disease in an area. Management requires someone who can observe larger areas of
disease incidence and levels of infection.
Weed control
Weeds reduce
yields by competing with the plants for sunlight, moisture, and soil nutrients.
Weeds may affect farming in many ways. For example, fertilizer applied might
not increase yields in weedy fields because weeds absorb nitrogen more
effectively than many rice plants. Also, weeds are harmful because they may be
alternate hosts for insect and disease pests of the main crop, and provide
shelter for rats. Usually weed problems are more serious in upland and rainfed
areas than in irrigated lowlands. If weeds are left to grow in the field, they
can significantly reduce yields. Knowledge of the behavior of weed species is
often lacking in the basic information available for weed control in most
developing countries. Control measures are generally adopted to reduce weed
infestation at certain phases of the crop cycle and not to bring about a
sustainable reduction of the infestation. In order to know when is the right
time to implement control methods to reduce weed species productivity,
knowledge is required concerning: weed productivity; time of germination/emergence;
and the period of fruit-setting and/or emission of first vegetative organs.
These studies also provide information on the negative or positive influence of
certain biotic and abiotic factors on weed growth and development. Weed
management must focus on the control of weed species, not only to avoid
competition but also to prevent further build-up of weed seed bank in soil and
eventually reduce it.
Field
sanitation and hygiene measures
The pathogens
that spread plant diseases and weeds can easily be spread by farmers and their
machinery, as well as other people that visit farm fields. Although many
pathogens are naturally present in the environment, they can also be spread by
humans (faeces, clothing and machinery) and through inputs (mainly irrigation
water). The main causes of contamination by pathogens that can be harmful to
humans are the use of animal manure or sewage waste as organic fertilizer and
the presence of animals in production areas. Composting of static piles
and earthworms do not guarantee that micro-organisms have been inactivated.
Wastewater and municipal wastes should only be used if effective disinfecting
systems are available. Other ways of reducing the spread of potential plant
diseases and weeds is to regularly clean farm machinery and clothing. Proper
field sanitation and hygiene measures are an easy way to prevent diseases from
spreading, but should always be combined with other measures, such as crop
rotations and intercropping.
Protection and enhancement of important beneficial organisms
The
configuration of the landscape can help to improve habitat for beneficial
organisms for pest control and pollination. Many ways exist of increasing these
organisms, such as conservation of keystone species/structures and natural habitats.
In rice systems, natural pest protection can be increased by small rows of
certain crops that attract the beneficial organisms in (or at the border) the
fields. For other crops, larger fragments of natural habitat
(e.g. Agroforestry) are needed. Attention should also be given, where
possible, to have a landscape that reduces the risk of the easy spreading of
plant diseases. This means that borders between crops have to be established,
based on the height and the distance that the pathogens/weeds can travel.
Overall, a higher biodiversity will reduce the risk of pest outbreaks, whereas
it will also benefit the biological processes that are needed for agricultural
production and create diversification of income and risks.
v Monitoring
of harmful organisms
Monitoring of
pests at a larger level (preferably transboundary) can help for the early
warning, early detection. contingency planning, early reaction, promotion of
environmentally sound control technologies and close collaboration and partnership
with affected countries, national and international agricultural research centers
and other international institutions. To strengthen the effort to address the
challenges of large-scale emergencies arising from transboundary pests and
diseases more effectively and to provide better coordinated and more timely
assistance to affected countries, FAO created a Food Chain Crisis Management
Framework (FCC). EMPRES Plant Pest and Disease will have a primary role in
emergency prevention, early warning and risk assessment, and in stimulating
synergy with the other EMPRES components. Whereas this is one larger component
of monitoring, at farm level the farmers should also be aware of what different
pests and beneficial organisms look like and what (if there is any) the
tolerable level is in the field. Coordination can be done through farm
organizations, but preferably also by communication with a national institute
(e.g. through mobile phones), that can inform other farmers and provide
measures that can be taken.
Establishment
of Economic Threshold Levels (ETL)
(ETL "the
population density at which control action should be determined (initiated) to
prevent an increasing pest population (injury) from reaching the economic
injury level." )
(Economic
Injury Level EIL: the lowest population density that will cause economic
damage)
The goal of
training for IPM is to empower farmers to make their own decisions. These
decisions are usually economic decisions about pest control and base their action
on the question ‘if I don't spray, will I loss some yield that worth more
than the cost of the spray?’ The decision requires knowledge of the
agro-ecosystem: recognition of pests and natural enemies, understanding of the
interaction of pests and natural enemies. The decision also requires knowledge
of the effect of pests on the yield of the plant and the effect of pesticides
on natural enemies.
The Economic
Threshold Level (ETL) is an attempt to improve decision making practices by
using partial economic analysis on the impact of a control practice, such as
spraying a pesticide. The ETL is computed usually based on three parameters
using the following equation:
ETL
= cost
of control ($/ha)
[commodity
value ($/kg) x damage coefficient (kg/ha/#pest/ha)
At the ETL, the
benefits of spraying are equal to the losses caused by the insects in the
field. There are many ways of making this definition, but they are usually
based on the same parameters. What is the use of the ETL? Traditionally, when
the ETL was surpassed (field populations are sampled and found to be higher
than the ETL) the farmer was advised to spray. IPM now includes a larger
analysis of the ecosystem. Other factors include levels of natural enemies, plant
health and ability to compensate for damage, other investment opportunities,
personal health, and weather are involved in the decision making process. The
ETL is still useful a part of the analysis, but not the only analysis.
Monitoring
of the success of the applied pest management measures.
Observing the
fields regularly is necessary to assess crop development, diseases, weeds,
rats, and insect pest populations. In most cases, an experienced IPM farmer
does this observation during a short time (usually less than a few minutes per
field) while carrying out other crop maintenance activities (irrigation, etc.).
Observations should determine how the crop is growing and if there are pests or
diseases causing yield-loss; remembering that not all injury causes yield-loss.
Natural enemies are usually present and sufficient to keep pests at low
numbers. Weather conditions, soil nitrogen levels, and degree of host plant
resistance will determine if diseases will subside or become more serious. In
the case of rats, community level dynamics determine rat infestations and
control programs. IPM Farmers must be knowledgeable of these factors to
properly and economically manage crops. In some cases natural enemies, plant
resistance and plant compensation cannot prevent yield-losses due to weeds,
rats, insects, or diseases. Proper assessments must be made to effectively and
profitably manage the use of inputs such as labour, quality seed, resistant
varieties, fertilizers, drainage systems, community organizing and pesticides
in order to ensure profitable production. Observation skills and decision
making are key to becoming an expert IPM farmer and require field level
practice for most farmers and extension staff.
v Sustainable
non-chemical methods of pest control
After monitoring
efforts in which pests are detected, farmers can compare the severity (damage
to plants and number of pests per area) to the economic threshold levels that
have been established. This can lead to the decision to take efforts to reduce
pest occurrence, first by non-chemical methods of pest control, and if this is
not providing satisfactory results, with chemical methods of pest control.
Whereas this is useful at farm level, it would be better to also take into
account the risk of rapid pest-spreading over a large area, by looking at the
distance that pests can travel and the size of the area (mainly monocultures)
that can be damaged by the pests. When the risk of spreading is high, early
warning can result in more efficient and less environmentally damaging efforts
to reduce the risk. Before pests become established, a smaller dose of
pesticides will be needed than once the pests have reached the field. Exact
measures will depend on the crop and landscape configuration, which means that
monitoring is needed at ecosystem, or higher, level.
Pesticides as
a last resort
There are
several alternatives to chemical pesticides that have to be evaluated before
deciding to use chemical pesticides. Alternatives include biological pest
control agents (BPCA) that include microbial and botanical pesticides, as well
as semiochemicals; all of which can be valuable components of IPM. The risk
associated with these biological pest control agents are favourable in
comparison with the conventional synthetic chemicals and in some cases they
might even be acceptable in organic production systems. Application of these
pesticides might be limited by their access and price, both of which can be
promoted by more favourable policies. In order to facilitate alternative methods
of pest control, a good understanding of each pest species and there natural
predator should be available for farmers. This can be promoted by
leaflets/flyers that include pictures of each species, together with possible
treatment measures. Economical justification should also not only include the
current cropping system, but also alternative cropping systems that might be
more resistant to pesticides (e.g. crop rotations and intercropping) and that
have been proven to be functioning in similar agro-ecological zones. A value
should also be attached to health risks and labour requirement.
Specific
application of pesticides to reduce the impact on human health and the
environment
Pesticides are
necessary in some fields, in some years and in some areas. In many seasons,
fields with a high diversity of crops do not need pesticides. Pesticides are
very dangerous to both the person who uses the pesticides and to those that are
living or playing near the fields where pesticides are used. Pesticides can
kill aquatic animals, beneficial predators and parasites, and other beneficial
animals such as pollinators. There is no use of pesticides that can be called
"safe" to everything in the ecosystem. Even the very selective
insecticide causes problems for the growth of shrimp and prawns. There is no
"safe use of pesticides". It is only possible to avoid their use and
reduce exposure when used.
Test on the
dosage of insecticide which kills test animals are called Lethal Dosage tests.
Basically the process is simple and depends on the fact that not all animals
will die with the same dosage because some individuals are more sensitive than
others. If a very low dose is applied to 100 individuals, only a few
individuals will die. If a very high dose is given, then most of the 100
individuals will die. The dose at which 50 of the 100 (50%) die is called the
50% lethal dosage or LD50. The dosage at which 90% of the individuals die is
called LD90. This is a moderately useful measure, except that even at low
dosages there is still an LD10 in which 10% die. Lethal dosages are
usually given in both oral (through the mouth) and dermal (exposure to skin)
levels. But pesticides cause other effects besides death. Other symptoms of
pesticide exposure include nausea, dizziness, headaches, fatigue, diarrhea,
irritation of nose, eyes, and throat.
Recommended Economic Thresholds for Insect Pests (As an Example)
|
Insect |
Crop |
Economic Threshold |
|
Alfalfa weevil |
Alfalfa |
>Hay: 25 - 50% of leaves on upper 1/3 of stem, or Seed: 35 - 50% of plants show damage or |
|
Aphids: Birdcherry-oat aphid |
Cereals Canaryseed |
12 - 15 aphids/stem prior to soft dough |
|
English grain aphid |
Cereals Canaryseed |
12 - 15 aphids/stem prior to soft dough |
|
Cabbage aphid |
Canola |
10-20% of the stem |
|
Turnip aphid |
Canola |
10 - 20% of the stems have aphid clusters |
|
Corn leaf aphid |
Cereals |
12 - 15 aphids/stem prior to soft dough |
|
Russian wheat aphid |
Cereals |
10% of the plants infested with at least 1aphid when first
node visible |
|
Green bug (aphid) |
Cereals |
12 - 15 aphids/stem prior to soft dough |
|
Potato aphid |
Flax |
2 - 3 aphids/main stem at full bloom * |
|
Pea aphid |
Pea |
2 - 3 aphids on top 20 cm of plant tip (Trapper peas can
withstand considerably higher levels) |
|
Armyworm |
Cereals |
> 10 larvae/m2 |
|
Thrips |
Barley, Oats |
7 - 8 thrips/stem prior to head emergence |
|
Beet Webworm |
Canola |
20 - 30 larvae/m2; Flax > 10 larvae / m2 |
|
Bertha Armyworm |
Canola (Napus) |
See chart below for variations |
|
Clover cutworm |
Canola, |
20 - 30 larvae/m2 |
|
Cutworms |
Cereals |
3 - 4 larvae/m2 |
|
Diamondback moth |
Canola, |
100 - 150 larvae/m2 in
immature and flowering fields ** |
|
Flax bollworm |
Flax |
3% of flax bolls infested |
|
Flea beetles |
Canola |
25% of cotyledon surface destroyed |
|
Grasshoppers |
Cereals |
8 - 12 grasshoppers /m2 |
|
Wheat midge |
Wheat |
Yield - 1 midge/4 - 5 wheat heads; Grade - 1 midge/8-10
wheat heads |
|
Painted lady butterfly |
Sunflowers |
25% defoliation when larvae are less than 30 mm (1.25 in.)
in length. Larger larvae have completed most of there destructive feeding and
treatment is not required. |
|
Plant bugs |
Alfalfa |
Seed: 4 bugs/sweep |
|
Pea leaf weevil |
Pea |
1 in 3 plants showing feeding damage on the clam leaf or
30% of the plants showing feeding damage |
|
Lygus bug |
Alfalfa |
Seed: 8 bugs/sweep |
|
Red sunflower seed weevil |
Sunflower |
Oil crop: 12 - 14 weevils/head at 85 - 100% bloom |
|
Red turnip beetle |
Canola |
Economic threshold not established. However control may be
required if beetles become numerous |
|
Sunflower beetle |
Sunflowers |
1 adult beetle/2 - 3 seedlings at the 2 - 6 leaf stage or
> 10 larvae per plant during summer |
|
Sweetclover weevil |
Clover |
First- year stands: 1 weevil/3 seedlings (1 weevil/5
seedlings under dry conditions) |
|
Wheat Stem Sawfly |
Cereals |
Economic threshold not established - see
"Cultural/non-chemical control" |
|
Wireworms |
Cereals |
Economic threshold not
established. Nominal threshold:32/m2 or greater
- seed treatment is required the following year |
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