What about IPM?

Integrated Pest Management (IPM) combines several appropriate pest control tactics into a single plan to reduce pests and their damage to an acceptable level. Using many different tactics to control a pest problem causes the least disruption to the living organisms and non-living surroundings at the treatment site. Relying only on pesticides for pest control can cause pests to develop resistance to pesticides, can cause outbreaks of other pests, and can harm surfaces and non-target organisms. With some types of pests, only using pesticides achieves very poor control.

To solve pest problems, first:

  • identify the pest or pests and determine whether control is warranted for each,

  • determine pest control goals,

  • know what control tactics are available,

  • evaluate the benefits and risks of each tactic or combination of tactics,

  • choose the most effective strategy that causes the least harm to people and the environment,

  • use each tactic in the strategy correctly, and

  • observe local, state, and Federal regulations that apply to the situation.

The best strategy for each situation depends on the pest and the control needed.

Can You Take Advantage of Natural Controls?

Some natural forces act on all organisms, causing the populations to rise and fall. These natural forces act independently of humans and may help or hinder pest control. It might not be possible to alter the action of natural forces on a pest population. Be aware of the influence of natural forces and take advantage of them when possible. Natural forces that affect pest populations include climate, natural enemies, natural barriers, availability of shelter, and food and water supplies.

  • Climate

    • Weather conditions, especially temperature, day length, and humidity, affect pest activity and rate of reproduction. Rain, freezing temperatures, drought, or other adverse weather may kill or suppress pests. Climate also affects pests indirectly by influencing growth and development of their hosts. A population of plant-eating pests is related to growth of its host plants. Unusual weather conditions can change normal patterns, increasing or decreasing possible pest damage.

  • Natural Enemies

    • Birds, reptiles, amphibians, fish, and mammals feed on some pests and help keep populations down. Many predatory and parasitic insects and insect-like species feed on other organisms, some of which are pests. Pathogens often suppress pest populations. Creating a backyard environment that attracts birds and other natural enemies of insects and other pests helps control these pests on desirable plants.

  • Geographic Barriers

    • Mountains and large bodies of water restrict the spread of many pests. Other landscape features can have similar effects.

  • Food and Water Supply

    • Pest populations thrive only if their food and water supply lasts. Once the food source is gone, the pests die or become inactive. The life cycle of all living organisms depends on access to water.

  • Shelter

    • The availability of shelter can affect some pest populations. Overwintering sites and hiding spots are important for some pests. Rocks and logs in a garden are a good example of where pests, like slugs and snails, may find a safe haven from the sun and predators.

What Are Applied Controls?

Unfortunately, natural controls do not always control pests quickly or completely enough to prevent injury or damage. At these times, other control measures are necessary. Those available include:

  • host resistance

  • biological control

  • cultural control

  • mechanical control

  • sanitation

  • chemical control

Host resistance

Some plants, animals, and structures resist pest attacks better than others. Some varieties of plants, wood, and animals are resistant to certain pests. Using resistant species and varieties, when available, helps control pest populations. Host resistance works in three ways.

  • Chemicals in the host repel the pest or prevent the pest from completing its life cycle.

  • The host is more vigorous or tolerant than other varieties, and less likely to be damaged by pest attacks.

  • The host has physical characteristics that make it more difficult to attack.

Biological control

A pest’s natural enemies, like parasites, predators, and pathogens, can be used against it. Supplement this control by legally releasing, or enhancing the environment favoring the growth of, a pest’s natural enemies in the target area. This might include creating habitats that favor predators or competitors not harmful to desirable host plants and animals.

Biological control usually does not eradicate a pest, and the degree of control can change. There is a time lag between a pest population’s increase and a corresponding increase in natural control. Under proper conditions, sufficient control can protect threatened plants or animals. Biological control also includes biologically altering the pest. This can include producing and releasing large numbers of sterile males; the use of sex attractants, called pheromones; or juvenile hormones. Pheromones can be used to monitor pest populations. Pheromones placed in a trap can attract insects in a sample area so that pest numbers are more easily estimated. Pheromones can also be a control tool. A manufactured copy of the pheromone that a female insect uses to attract males can be used to confuse males and prevent mating, creating lower numbers of pests. Applying juvenile hormones to an area can reduce pest numbers by keeping immature pests from becoming normal, reproducing adults.

Cultural controls

Changing the environment, the condition of the host plant or animal, or the behavior of the pest can prevent or suppress an infestation. Cultural controls disrupt the normal relationship between the pest and the host plant or animal and make the pest less likely to survive, grow or reproduce. Common cultural practices include rotating crops, cultivating the soil, varying the time of planting and harvesting, planting trap crops, adjusting row width, and pruning, thinning and fertilizing cultivated plants.

Mechanical controls

Adding physical controls to the environment, the host plant or animal, and the pest can prevent the spread of pests. Mechanical controls include traps, screens, barriers, fences, nets, radiation, and electricity. Lights, heat, and refrigeration can alter the environment enough to suppress or eradicate some pest populations. Altering the amount of water, including humidity, can control some pests, especially insects and disease agents.

Sanitation

Keeping an area clean can help prevent and suppress some pests by removing the pests or removing their sources of food and shelter. Improve cleanliness, eliminate pest harborage, and increase the frequency of garbage pickup to reduce urban and industrial pests. Good manure management practices can prevent pests that attack domestic animals. Removing crop residues, and decontaminating equipment, animals, and other possible carriers before allowing them to enter a pest-free area or leave an infested area reduce the carryover of agricultural pests from one planting to the next. The proper design of food-handling areas reduces access and shelter for many pests.

Chemical control

It is common practice to use pesticides to destroy, control, or prevent pests from causing damage. Some pesticides attract or repel pests. Chemicals that regulate plant growth or remove foliage are also classified as pesticides. Disinfectants and other common household chemicals are classified as pesticides as well. Depending on the pest, pesticides can be the fastest way to control pests. In some instances, they are the only tactics available.

Written by: Michael J. Weaver, Professor & Director- Virginia Tech Pesticide Programs, 2018.