Pest Management 101

Maggie Scarbrough

Pest control has been around since the beginning of time. What started as humans clubbing rats and using mercury or arsenic to control lice, has become a well-regulated system of integrated pest management using specific pesticides and application methods. In this packet, we will go over today’s standard of identifying pests, control methods and integrated pest management.

Pest Recognition

The four main groups of pests are as follows:

  1. Weeds – Undesirable plants
  2. Invertebrates – Insects, mites, ticks, spiders, snails and slugs
  3. Disease Agents or Pathogens – bacteria, fungi, viruses, nematodes and mycoplasms
  4. Vertebrates – birds, reptiles, fish, amphibians, rodents and other mammals.

Familiarity with pests is directly related to proper pest management. Misidentification or lack of information could cause pest control failure and damage to non-target organisms. For example, say you inspect a plant with damage. Was that damage caused by living pests or environmental factors like weather, air pollutants or bad fertilization?

Identifying organisms is made easy by referencing identification books, county bulletins, field guides and online identification keys. If you can not find the information you are looking for through those resources, you can always send a specimen to your local university diagnostic lab or pest management specialist. Getting help with identification through a lab or specialist is especially helpful when a microscope or special testing is needed to identify the pest, such as small mites or nematodes.

Pests may also leave clues that help you to identify them and/or their presence. For example, you can track feeding habits, damage caused from feedings, excrement, nests, burrows, gnaw marks and tracks and match them to common characteristics of vertebrates and invertebrates. Weeds may cause flowers, seeds, fruit or unusual growth habits in plants. Fungi or pathogens may cause damage, deformation or color changes in their host.

Pest Management Methods

Now that you have identified the pest problem, you must determine the most effective way to control it while causing the least amount of harm to people and the environment. Common pest management methods are: biological control, chemical control, cultural control, genetic control, mechanical control, and regulatory control.

Before we get into those methods, let’s talk about abiotic factors. Abiotic factors are nature’s pest control. These environmental factors (e.g., wind, temperature, climate change, sunshine, rain, rivers, lakes, mountains and air and water pollution) naturally affect pest infestations and movement. When these factors do not properly control pests in an area, they must be controlled by different, man-made tactics.

Biological Control

Biological control still relies heavily on nature to control pests, as it refers to introducing a pest to its natural enemy. Laws and regulations strictly control this method so that the natural enemy brought in does not become a new pest issue. If successful, these biocontrol agents (a.k.a. The natural enemy) become established and lower the target pest population for long periods of time with no human intervention. These types of biocontrol agents are brought in to manage specific insects, mites, fungi, fish and weeds.

Biological control is also used in agriculture to protect crops without the use of pesticides. Since crops go in and out of season, biocontrol agents are released periodically and are crop specific. For example, predatory mites are released to control plant-feeding spider mites and praying mantids, lady beetles and lacewings are released to manage pests in greenhouses and gardens.  

Chemical Control

Commonly used in pest control, chemical control is the method that uses either naturally derived or synthetic chemicals to manage pests. These chemicals are known as pesticides, and are defined as “any material that is applied to plants, soil, water, harvested crops, structures, clothing, furnishing or animals to kill, attract, repel, regulate or interrupt the growth and mating of pests.” For some pests, this is the only known control method!

The use of pesticides controls pests effectively, quickly, easily and cost efficiently. Pesticides contain a wide assortment of chemicals and each has a specialized function. Below is a list of pesticides with the pest they control.

  • Avicides – Controls birds
  • Bactericides – Controls bacteria
  • Chemosterilants – Sterilizes insects or pest vertebrates
  • Defoliants – Causes leaves to drop from plants
  • Desiccants – Promotes drying or loss of moisture from plant tissues and insects
  • Disinfectants – (a.k.a antimicrobials) Controls microorganisms
  • Fungicides – Controls Fungi
  • Growth regulators – Alters the growth of a plant or animal
  • Herbicides – Controls weeds
  • Insecticides – Controls insect and related arthropods
  • Miticides – (a.k.a acaricides) Controls mites
  • Molluscicides – Controls snails and slugs
  • Nematicides – Controls nematodes (a.k.a roundworms)
  • Ovicides – Destroys eggs
  • Pheromones – Attracts insects
  • Piscicides – Control pest fish
  • Predacides – Controls predatory vertebrates (a.k.a.coyotes)
  • Repellents – Repels insects, mites, ticks, pest vertebrates, invertebrates, birds and mammals
  • Rodenticides – Controls rodents

Each group of pesticide listed contains several classes or families with similar chemical structures that share common modes of action (how they kill pests) and sites of action (the biological system affected within the target pest). For example, insecticides include organophosphates, organochlorines, carbamates, pyrethroids, botanicals, insecticidal soaps and microbials.

Chemicals can be either selective or non-selective pesticides. Selective pesticides are toxic to a target pest, but have little no effect on non-target organisms. For example, an herbicide may control a broadleaf weed very effectively while having no effect on grasses. Non-selective pesticides, on the other hand, will kill a wide variety of pests. For example, fumigants will kill fungi, weeds, insects, nematodes and almost anything else in its path.

The site of action also varies throughout pesticides. Systemic pesticides are absorbed and transported through the target pest. In plants, pesticides are absorbed through leaves or roots and then travel throughout the plant. In livestock, systemic pesticides are eaten or injected before traveling through the body to control pests. Contact pesticides must directly touch the plant or animal in order to be effective.

Pesticide persistence is the amount of time the pesticide actively controls pests. Some pesticidal activity can go on for weeks, months or even years while down to a few hours.

Cultural Control

Cultural pest control consists of practices that naturally prevent pest reproduction, dispersal and survival. For example, pest build up and damage can be prevented if turf is regularly mowed, irrigated, aerated and fertilized. While common lawn care takes care of turf, careful planning goes into the cultural control of agriculture production. Selection of crop varieties, timing of planting and harvesting, cultivation, irrigation management and harvest, crop rotation and trap crops are used to control weeds, microorganisms, insects, mites and other pests.

Two popular and effective culture control methods include cultivation and sanitation. Cultivation uses tools such as plows, disks, mowers, cultivators and bed conditioners to control weeds and disrupt living conditions for some microorganisms and insects.

Sanitation is the process of taking away the food, water and shelter pests need to survive. In agricultural production, this involves removing weeds that give shelter to pests and rodents, destroying diseased plant material, killing weed plants before they produce seed and keeping field borders. In areas of insect control, sanitation measures are pretty common sense. Good manure management practices in livestock operations reduces fly problems, draining standing water controls mosquitos, garbage clean up and containment controls cockroaches, taking away a food source reduces rodent and fly problems and soil, trash and wood removal around buildings can reduce termite or fungal rot damage.

Genetic Control

Genetically controlling plants and animals is a method that has been widely used in the past and will likely be an effective tool in the future. While certain plant varieties are naturally resistant to some insects, pathogens,nematodes, pest and toxic substances, if a plant cannot defend itself against a target pest it may achieve resistance when genetic material is transferred from insect-destroying microorganisms to a hybrid seed. For example, when plants are genetically modified to contain Bacillus thuringiensis (BT), they develop a tolerance to herbicides, are protected from pests and have an overall improved quality.

Mechanical/Physical Control

Mechanical pest control is really just a fancy word for using a trap. Depending on the device, the trap may be a mechanical device or a sticky surface that kills the animal or catches it for relocation.

Physical pest control creates an unsuitable environment for the target pest. This includes mulching for weed management, steam soil sterilization for disease control and sealing cracks and crevices in buildings. Simple changes in our environment can make a big difference in a pest’s environment. Storing insect ridden items (e.g., furs or food) in cool temperatures (e.g., a refrigerator) will cause the to stop feeding, thus preventing eggs from hatching and developing. Installing bright lights in an attic or garage may prevent bats from roosting there. Increasing air movement in greenhouses prevents fungal disease from developing on plants.

Regulatory Control

When pest problems cannot be controlled at a local level and have the potential to endanger public health or cause widespread damage to crops, animals and forests, the government steps in with quarantine and eradication programs.

Quarantines are put in place to prevent entry of certain pests into pest-free areas and/or prevents movement of a designated pest within a state. During a quarantine, inspection stations run by regulatory agencies may be required at all major entry points to ensure that no pest or materials containing the pest enters the area.

Eradication is the elimination of a pest (often one that is already under quarantine) from a designated area. In order to completely eliminate a pest from a defined area, the geographical extent of the pest infestation is determined and control measures are taken from there. Procedures to eradicate a pest may include an area-wide spraying program or the release of sterile insects with close monitoring of the pest within and around the border of the defined area. An example of an organism that may be issued to be eradicated is a weed or plant that is a fire hazard, harbors harmful pathogens or animals or is toxic to animals or people.

Integrated Pest Management

Integrated pest management (IPM) is a balanced, tactical approach to pest control. Instead of relying heavily on pesticides, IPM uses cultural, biological, mechanical and chemical methods to treat target pests, anticipate pest outbreaks and prevent pest damage.

There are many reasons for every pesticide business and applicator to practice IPM. Less pesticide use means less risk to harmless and/or beneficial organisms, reducing environmental injury and helping to maintain a balanced ecosystem. IPM cuts costs by preventing damage caused by pests and eliminating the need for unnecessary pesticides. Lastly, IPM promotes a good public image. As more natural remedies are being requested, controlling pests without the use of pesticides promotes professionalism and shows you care for the health and safety of your community.

Good IPM strategies take time to master and vary depending on the area you are in. The main components needed in an IPM approach are as follows:

  1. Identify the pest – Whether you are dealing with insects, weeds, plants or vertebrate animals, you must identify the pest to determine its significance and need for control. A pest with little impact on a plant or animal may not need to be controlled, while high impact pests require immediate control to prevent damage from occurring. There are three categories of pests :
    1. Key Pests – If they go uncontrolled, key pests may cause major damage on a regular basis. Weeds are a key pest because they compete with crop or plants for resources. Cockroaches and rodents are also key pests because their waste and body coverings may cause disease in humans and animals.
    2. Secondary Pests – These pests become an issue when the key pest is eliminated. Weeds that were once dominated by “key pest” weeds begin to flourish and pets treated for fleas and ticks may move to people after their host is taken away.
    3. Occasional Pests – These pests are rarely troublesome due to their life cycle, environmental conditions and changing human activities. For example, ants may become an issue when sanitation practices change and provide them with new food resources or they may move into a building after an environmental event (rain) destroys their outdoor food source.
  1. Monitor the Target Pest – Regular monitoring is key to successful IPM programs. Paying attention to plants and animals over time and in different conditions along with trapping are tools used to monitor insects. Pest specific weather and temperature models can assist in predicting the need and timing of pesticide applications.
  1. Develop the Pest Management Goal – Prevention and suppression techniques are often combined to keep pest damage at economical and aesthetically acceptable levels. A solid IPM program coordinates the use of multiple methods into one integrated system. Once you know what the goal is, consider the different methods that may be used to reach that goal, then evaluate the costs, benefits and liabilities of those combined methods. Keep in mind that you must always observe all local, state and federal regulations regarding the methods you choose.
  1. Implement your IPM program – Once you have all methods in place, it’s time to initiate your program. The IPM program may be slightly adjusted as you learn more about the target pest(s) and the job site.
  1. Record and Evaluate Results – Every pest management effort performed should be followed up with detailed records. Objectively evaluating how well your strategies work will better prepare you when creating other IPM programs.

Pest Population Thresholds

With all the talk of control methods, it may come as a shock that sometimes it is better to not treat a pest. The economic threshold (ET) refers to the cost of control in relation to the size and potential damage caused by a pest population. The ET also refers to the pest population density at which control measures are needed to prevent the pest from reaching the economic injury level (EIL). The EIL is the pest population density that causes losses equal to the cost of control measures. Before justifying a control measure, you must set the ET before the EIL, otherwise producers will lose money not only from the damage caused by a pest, but also from the cost of controlling the pest. Setting the ET below the EIL allows the control method to take effect before reaching the point of EIL. Below is an example:

Why Pesticides Fail

When combined with other control methods, pesticides are an effective component of an IPM plan. When pesticide applications do not control pests as expected, it is important to know how to figure out where the problem occurred.

  • Incorrect Pest Identification – Accurately identifying pests requires patience and practice and is necessary to choosing the correct control method. For example, applying Bacillus Thuringiensis will control caterpillars but not a sawfly. These two pests also have different life stages, so many non-chemical tactics will fail if you mistake one for the other.
  • Incorrect Application Rate – Applying the correct amount of pesticide according to the label ensures that you are controlling the pest. Applying too little may cause you extra time and money if you have to retreat the area.
  • Incorrect Use – Herbicides may be created to kill grass, broadleaf weeds or even both. Be sure you read the label carefully to check for the intended target pest.
  • Incorrect Timing – Knowing the habits and life cycles of pests allow you to plan your applications appropriately. Failure can occur if the pest is not in the area at the time of treatment or it may be in a life cycle stage that is not susceptible to the pesticide.  
  • Incorrect Equipment – The more difficult a pest is to reach the more important the choice of equipment is. For example, an air blast sprayer is best for pests hiding under apple tree leaves and granular applicators are better during planting operations for soil-dwelling agronomic pests.
  • Poor Environmental Conditions – Conditions such as heavy rains, extremely high or low temperatures and high winds can move pesticides away from the target pest and site. This causes pesticide failure as well as contamination risk.
  • Poor Storage – Pesticides degrade when stored over a long period of time or improperly, causing them to be ineffective. Be sure to check the expiration date and consistency of the chemical before applying it.

Summary

  • The four main groups of pests are as follows:

Weeds – Undesirable plants

Invertebrates – Insects, mites, ticks, spiders, snails and slugs

Disease Agents or Pathogens – bacteria, fungi, viruses, nematodes and mycoplasms

Vertebrates – birds, reptiles, fish, amphibians, rodents and other mammals.

  • Abiotic factors are nature’s pest control. These environmental factors (e.g., wind, temperature, climate change, sunshine, rain, rivers, lakes, mountains and air and water pollution) naturally affect pest infestations and movement.
  • Each group of pesticide listed contains several classes or families with similar chemical structures that share common modes of action (how they kill pests) and sites of action (the biological system affected within the target pest).
  • Non-selective pesticides, on the other hand, will kill a wide variety of pests. For example, fumigants will kill fungi, weeds, insects, nematodes and almost anything else in its path.
  • Pesticide persistence is the amount of time the pesticide actively controls pests. Some pesticidal activity can go on for weeks, months or even years while down to a few hours.
  • Cultural pest control consists of practices that naturally prevent pest reproduction, dispersal and survival.
  • When pest problems cannot be controlled at a local level and have the potential to endanger public health or cause widespread damage to crops, animals and forests, the government steps in with quarantine and eradication programs.
  • Secondary Pests – These pests become an issue when the key pest is eliminated. Weeds that were once dominated by “key pest” weeds begin to flourish and pets treated for fleas and ticks may move to people after their host is taken away.
  • The economic threshold (ET) refers to cost of control in relation to the size and potential damage caused by a pest population.
  • With all the talk of control methods, it may come as a shock that sometimes it is better to not treat a pest.