Author: Howard Moss

Modern agriculture seeks effective ways to protect crops against pests that can cause considerable revenue losses. Ideally, such control tactics should be ecologically and human-health benign.

IPM includes preventive measures (exclusion, trap crops, mating disruption, sterile insect releases, and other biological controls), plant physical defenses, and chemical management of pest populations above a determined acceptable level of injury or economic threshold. Check out Pest Control Columbia MO for more information.

Prevention

The goal of prevention strategies is to stop a pest problem before it starts. Depending on the audience, this could be at the home level (like setting traps for mice) or in agriculture (using crop rotation and soil management to reduce the threat of disease-causing pathogens). This is often achieved through cultural control. Cultural methods involve changing the environment in which a pest occurs to make it less favorable for them, such as removing weeds, keeping food in sealed containers to prevent infestation by rodents, or cleaning up fallen leaves where mosquitoes might lay eggs.

A pest can be any organism that degrades, diminishes, or destroys a natural resource and causes damage to plants, animals, or humans. The term pest is defined by Merriam-Webster as any organism that “destroys or annoys” humans and can include plant species (such as invasive weeds) and animals (like bees and wasps).

An organism may rise to the level of a pest because it has escaped normal control by natural regulating agents. This can happen because the organism is imported to a new region (called classical biological control) or because human activities decrease the populations of natural enemies of a particular pest. In some cases, native natural enemy populations migrate to a new region and control an invasive pest population (called fortuitous biological control).

Many different pests can be managed through the use of pheromones or semiochemicals. These chemicals are used to change behavior by altering the communication of organisms in a given area. For example, mating disruption pheromones can be used to reduce pest populations by altering the way they meet and mate.

Physical and mechanical control methods remove or exclude pests from an area. These techniques can include physical barriers such as fences and nets or mechanical removal using sticky cards, sweep netting, or hand picking. Biological controls such as predators, parasites, or pathogens can also be used to manage pests. However, biological controls are most effective for small pest invasions and they take time to work.

Chemical controls can be useful for managing a pest when all other options have been exhausted or when the pest has reached an economic threshold or nuisance level. Chemicals can be used in combination with other control techniques and should always be used with caution and with the goal of minimizing environmental impact.

Suppression

When pests have already invaded a field or other area, suppression strategies seek to reduce their numbers and damage to an acceptable level. This may be done with natural enemies, predatory species that prey on pests; pathogens, microbes that attack or kill disease organisms; or chemical agents that disrupt the life cycle of pests by attacking their nervous systems or other essential functions.

Most treatment sites are complex ecosystems with living organisms (people, plants, and other animals) as well as nonliving surroundings such as soil, water, air, structures, and objects. The actions of each type of organism or component usually affect the action and well-being of others at the site. When pest control efforts are taken, they must take into account the effects of these strategies on all components of the system.

In general, the most desirable outcome for a pest control strategy is to prevent the pest from invading or harming crops in the first place. This can be accomplished by using pest-free seeds and transplants, avoiding field locations and conditions conducive to disease development, scheduling irrigation to avoid moisture stress that favors disease infection, cleaning tillage and harvesting equipment between fields or operations, practicing crop sanitation procedures, removing alternate hosts for insect pests and plant diseases, and using weed killers to keep weeds from competing with desirable plants for resources.

Some pests are recurring problems that require constant or regular control. These are called continuous pests. Other pests are sporadic, migratory, or cyclical, and require periodic control. Still others are potential pests, which do not cause harm under normal circumstances but could become a problem in certain conditions.

Suppression strategies for these pests are generally targeted to specific areas or seasons. In general, they are less effective than prevention strategies.

The effectiveness of different suppression strategies is usually compared against one another, and the best performing strategies are identified. This can be done by evaluating the performance of each control effort against several metrics that reflect pest population dynamics. For example, the use of green insecticides, mating disruption, and plant removal can be evaluated against each other to see which combination of control measures produces the highest performance criterion.

Eradication

When a pest population is so high that its presence threatens the economic or aesthetic health of the plant or environment, an eradication strategy may be needed. The goal is to bring the pest numbers down to an acceptable threshold where additional controls are not cost-effective. Eradication strategies are rare in outdoor situations, but are more common for invasive plants and pests found in greenhouses, nurseries, food processing and storage facilities, and in indoor residential and commercial settings.

Eradication strategies often involve biological control tactics, but not necessarily as a replacement for chemical controls. This involves using predators, parasites, and diseases to reduce the populations of unwanted organisms. In addition, promoting the existence of natural enemies, such as beneficial insects or weed species that can serve as a food source for a particular pest, can reduce pest numbers. This can be achieved by reducing the use of broad-spectrum insecticides that can disrupt the populations of these natural enemies, or by introducing beneficial insects to the landscape or crop fields.

Behavioral control strategies can also be used to reduce pest populations without directly killing them. This can be done by altering their mating or aggregation behavior with the use of pheromones or semiochemicals. For example, pheromones that interrupt the mating process of certain moths can be used to reduce their populations in fruit or vegetable fields. Likewise, the use of chemicals that interfere with host identification or with feeding can cause pests to disperse.

Identification of the pest is essential for developing an effective pest control program. This is particularly true for eradication strategies, which require accurate identification of the pest to be sure that it is being treated and that the treatments are working. Scouting and monitoring should be done regularly to assess the situation and determine if pest populations have reached an unacceptable level. In a greenhouse, for example, scouts should look under leaves, along foundations and at bait stations to check for the presence of mosquitoes. This regular activity allows the scouts to treat only where necessary, minimizing overall pesticide usage.

Integration

The best way to prevent pests and their damage is with integrated pest management (IPM). This approach combines multiple control tactics, including biological controls, and uses monitoring and evaluation to determine the effectiveness of each tactic. Its goal is to reduce costs for growers and minimize the impact of pest control methods on non-target organisms and the ecosystem as a whole.

IPM programs typically start with a problem assessment. This consists of a careful observation of the plant to determine the scope and severity of pest damage, as well as an accurate identification of the organism that is causing it. Once a risk level is established, prevention strategies are implemented. This includes crop rotation, planting pest-resistant species, or using pre-treated seeds. Sanitation practices can also be very effective at reducing pest populations, for example by eliminating food sources or depriving them of shelter. For example, mulching around plants helps prevent weed growth while keeping soil temperatures and moisture levels adequate for optimum plant growth. In urban environments, good garbage pickup and frequent cleaning of equipment and food containers can help reduce pest carrying over from one area to another.

In many cases, IPM programs use cultural and physical control tactics rather than chemicals. This may include screens, floating row covers, or food-storage containers that limit access to pests; traps, baits, and lures that deter them; and planting in areas where pests cannot easily get to the plants. IPM programs also often rely on natural resources to keep pests in check, for example by planting plants that naturally repel them or by introducing predators and parasitoids into the environment.

Chemical control is usually used only when other management techniques are ineffective or impractical. This is because overuse of pesticides can cause them to lose their effectiveness and lead to resistance in the pest population. Therefore, it is critical to carefully evaluate each pesticide before applying it, as well as periodically monitor and reevaluate the effectiveness of all control tactics.

Pests live and thrive in an environment that provides them with the basic necessities of life – food, water, and shelter. If any of these elements are denied, they may not be able to sustain themselves and will need to seek out new food or shelter. This is why it is so important to select the most appropriate plants for our climate, plant them in the right place, and provide them with the care they need to remain healthy.