What is IPM?

To understand how and why Integrated Pest Management (IPM) was developed and its relevance to us today, we need to look back at the time when advances in synthetic chemistry changed our way of life in wartime and in peace time. Pesticides are a central part of this story. The proven efficiency of synthetic pesticides, particularly DDT during World War II, gave people hope that insect-borne diseases could be conquered, and crop pests could become a thing of the past. Some of these hopes were realized as malaria was eradicated in some parts of the world, and the Green Revolution at first appeared to be a solution to world hunger. But widespread, routine use of DDT and other  pesticides on farms, wildlands, forests, cities and homes resulted in catastrophic consequences, which led to the birth of the American environmental movement and the development of IPM.  The City of Boulder is part of this story. Boulder was the first city in the nation to enact a "right-to-know" ordinance to notify residents about pesticide applications. Boulder was also one of the first cities in the nation to adopt an Integrated Pest Management program and policy.

The concept of IPM was developed for agriculture in the late 1950's to address insect outbreaks and ecological disruption from the overuse of post-war pesticides. The objective of IPM is to use information/knowledge and site-specific criteria to support conditions that allow natural forces to keep potential pest populations under an acceptable threshold. In balanced ecosystems, an array of organisms each have different roles and interactions with each other. Abiotic or nonliving factors, including temperature, light, minerals, humidity, atmospheric factors, etc. also shape the functioning of each ecosystem. These interactions are complex with multiple feedback loops at different scales that keep well-functioning ecosytems within stable bounds. In the absence of human disturbance, the majority of time, species will not breed uncontrollably or crash to extinction. This is the "balance of nature" that IPM aims to maintain or restore. Generally, more biological diversity in an ecosystem leads to more stability and resilience that not only keeps a species from exploding in numbers or crashing, but also provides buffering potential from stressors, including external stressors like climate change or human interventions.

IPM concepts can be applied to any ecosystem - whether artificial environments like agriculture and urban areas, or in wild and natural areas. IPM at its core is applied ecology. Over the years, the ecological concepts of what constitutes the practice of IPM have been blurred. Even large monoculture crop systems that are heavily reliant on chemical inputs, including prophylactic insecticides, are defined by some as IPM. Different perceptions and a wide range of interpretations of what IPM is or isn't can be confusing. Boulder's IPM Policy requires an ecosystems-based approach that aligns with the foundational principles of the original IPM concept. Regardless of a particular IPM philosophy, it is widely accepted that IPM is best practice and most practitioners would agree in principle that pesticides should be applied with caution after a pest is present at levels that can lead to harm or economic loss. This wasn’t always the case. 

Pesticides are substances used to kill or repel any kind of pest, including insects, weeds, and fungal diseases. Pesticides and other methods to exclude or prevent pests have been  used for centuries . As early as 2500 BC, Sumerians used sulfur to control insects and mites. Over the next few thousand years, civilizations around the world used heavy metals including arsenic and mercury, or poisonous plants to kill pests. Tobacco started being used as a pesticide in the late 1600's, and nicotine was extracted by the late 1700's for use as a fumigant. Around 1800, pyrethrum products were developed. Later in that century, developments in synthetic chemistry techniques would completely change the playing field for pest control.

DDT was first synthesized by German chemists in 1873. But it wasn't until 1936 that another chemist, Paul Herman Mueller who would later win the Nobel Prize, discovered DDT's insecticidal activity and patented it in 1940. DDT is a potent insecticide that in small doses can kill insects for months after a single application. We now know DDT lasts in the environment for decades.

Britain and the U.S. used DDT to control insect-borne diseases like malaria and typhus that killed hundreds of thousands of people during the war. By 1944, DDT was being delivered to the the U.S. and British military in Europe where it ended epidemics in their tracks by wiping out lice and mosquitoes, which saved countless lives both in the European and Pacific War Theaters.

More soldiers died from insect-transmitted diseases than from combat or any other war-related cause. When DDT arrived on the scene, the world had never witnessed such an effective insecticide. DDT could exterminate and eliminate pest insects, and it was considered a miracle that could save lives and win humanity's long war against hunger and disease.

The weapons used were closely tied to their time period: World War I had seen the first systematic use of poison gas and what worked in the trenches often worked on the farm. The war was a ​“Cinderella-like transformation of the American chemical industry,” and after the World Wars, synthetic organic compounds used for defoliation, to make weapons and as insecticides to protect troops were promoted and sold for use in the civilian market.

DDT was aggressively marketed and the marketing campaigns were highly effective. The public had few concerns about extensive and widespread use, including in the home, due to claims of safety by both the manufacturers and the government.

Although the majority of scientists, regulators and health officials enthusiastically embraced DDT to eradicate malaria, protect crops, and conducted aerial spraying over nature preserves to attempt to eradicate pests like gypsy moth, some scientists voiced concerns. Among them was Fred Bishop who wrote about the "wonder insect killer" in a 1946 article in the American Journal of Public Health ( link to the original article ). He reviewed studies from other scientists about DDT's toxicity to all mammals, and noted, "One of the outstanding characteristics of DDT is its persistence."

Bishop also warned about the effect of DDT on "beneficial forms of life," discussing direct toxicity to birds, fish, frogs, crayfish, and cascading impacts to animals feeding on insects "dying from DDT tremors." He expressed "considerable anxiety" about effects to beneficial insects that are predators and parasites of pest insects.

As early as 1945, Rachel Carson, then a marine biologist with the Fish & Wildlife Service, submitted a manuscript to the Reader's Digest voicing her concerns about the lack of testing of DDT and its potential impacts to the "delicate balance of nature." Her manuscript was rejected.

Carson became famous in the 1950's for writing award-winning books about her love of nature and the sea. Her writing career took a different path when a set of circumstances led to Carson writing one of the most impactful publications in modern history, the book Silent Spring. Carson's unanticipated shift in direction was set when a member of a citizen's group in Massachusetts contacted Carson asking if she would write about a lawsuit they'd filed to stop statewide DDT aerial spraying. By this point, insect pests were becoming resistant to DDT, while wildlife were dying from exposure to it. Carson agreed to write about this issue, which she pitched to the New Yorker magazine. This led to a close working relationship between Carson and the New Yorker that lasted through the end of her life. Carson began meticulous research of a large body of scientific literature as she started to work on the story. Instead of an article, her extensive investigation became a book. It took Carson four years to complete Silent Spring, due in part to her personal circumstances, but also due to the magnitude and analysis of the material she uncovered during her research. Carson cared for ailing and dying family members for several years, leaving her alone to raise her young orphaned nephew. She became ill herself with cancer, but continued working on the book and kept her cancer a secret. She completed Silent Spring, which was initially published in 1962, as a three-part series in the New Yorker. The book became a best seller and ignited a firestorm. Carson was viciously attacked by the chemical industry. However, these attacks backfired on the industry by bringing even more attention to Silent Spring. Though she was dying, Carson appeared on television news shows and testified before President Kennedy's Science Advisory Committee, which supported her claims that DDT and other post-war pesticides were threatening the balance of ecosystems. Her work created a seismic shift in environmental policy in the U.S., leading to the establishment of the Environmental Protection Agency (EPA). Federal environmental laws were enacted to reduce pollution to protect the public and the environment. These included major revisions to FIFRA (Federal Environmental Pesticide Control Act) to increase pesticide regulation and the transition of pesticide regulation from the USDA to the newly formed EPA. The Clean Air, Water, Endangered Species, National Environmental Policy, and Wilderness Acts were all enacted into law. 

At the same time that Rachel Carson was researching and writing Silent Spring, agricultural scientists, particularly those who worked on biological control and "natural enemy insects" (insects that prey on or parasitize crop pests), were also becoming concerned about the volume and application of DDT and other post-war pesticides. They were alarmed that crop pest insects were becoming uncontrollable due to resistance to DDT and other synthetic pesticides, resurging to or beyond pre-treatment levels. New pest infestations also emerged - "secondary pests" that had previously been harmless before pesticides killed insect predators and parasites, which had kept their populations low. Unchecked, these new pests spiked to damaging levels. Collateral non-target impacts included killing pollinators and birds. Pesticide runoff contaminated waterways and harmed fish, amphibians and aquatic insects. In contrast to the status quo of the time that focused on pest eradication and efficiently killing as many pest insects and weeds as possible with regular applications, these scientists proposed using a combination of ecologically-based practices to restore balance in agricultural ecosystems and support natural enemies and other natural factors to prevent pest insects from reaching damaging thresholds. Initially, their focus was balancing pesticide use with minimizing its impacts. The first major paper by the "Fathers of IPM" was published in 1959 using the term "integrated control."

As the field of IPM matured and developed, its multi-disciplinary approach strengthened, incorporating ecological principles and viewing an agricultural field the same way as any other ecosystem. Successful implmentation requires knowledge, observation and incorporating crop and other plant diversity to these systems to support as much biodiversity as possible. It requires careful monitoring of not only a potential pest, but other insects and animals, the plant community, microganisms, etc. to track the impacts of interventions. Pests were viewed as members of an ecosystem, and the focus shifted from being pest-centric to managing an ecosystem so that natural factors could keep potential issues from occurring.

This evolving approach was reflected in the first authoritative and detailed guide that describes the history, science and principles for integrated pest management,  Introduction to Integrated Pest Management . The first paragraph of the book questions previous notions of pests and sets the stage for a new discipline using applied ecology to prevent pest issues.

The definition of "pest" is totally human-oriented. Organisms designated pests compete with people for food, fiber, and shelter; transmit pathogens; feed on people; or otherwise threaten human health, comfort, or welfare. It could be said that, previous to the appearance of humans, there were no pests-just millions of different organisms struggling for survival; the arrival of humans and the continuing development of the human life-style have provided the sole basis for labeling an ever-increasing number of these surviving organisms "pests."

During this time period, the public, the government and researchers began to develop a new awareness of the potential dangers of pesticides, as well as the necessity of protecting biodiversity though ecological principles applied to land management. The industry developed new pesticide chemistries to replace DDT and other pesticides from that era. These new pesticides were assumed safer, but issues have emerged with each subsequent generation of pesticides. An assumption of safety can lead to complacency about the ecological and human health impacts, encouraging more reliance on pesticide use. This can lead to land management practices that are not ecologically sound.

The impetus for the first neighbor notification ordinance in the nation began in Boulder on a warm sunny day. Two friends, one pregnant, were inside their house when a neighbor's tree was sprayed with insecticide that drifted through the open window into the house, exposing them both. They decided to do take action to try to prevent this from happening again to them or to anyone else, which ultimately led to an ordinance that requires notification signage at the time of a pesticide application. This now common yellow sign was designed by Boulder's code enforcement officers for this ordinance. The ordinance also required 24 hours advance notice to adjacent neighbors for any pesticide application that takes place at 5 feet or higher. The city was promptly sued by a newly formed group of commercial pesticide applicators, COPARR (Colorado Pesticide Applicators for Responsible Regulation ) and the city won. COPARR appealed but the case was dismissed when the U.S. Supreme Court upheld the right of local governments to regulate pesticides in a case that involved a Wisconsin city government. The city's ordinance has now been preempted by state law that prohibits local governments from regulating notification for commercial pesticide applicators and from regulating pesticide use within their jurisdictional boundaries. An important legislative priority for the city is to restore the authority for local governments to regulate pesticide use.

During this same period, city staff were taking initiative on their own to develop ecologically sound and non-chemical weed management practices. OSMP hired their first ecologist around 1990 during the department's transition from land acquisition to land management. This new ecologist built a program that was interdisciplinary and ecosystem-based using a landscape-scale view. OSMP staff from that period describe it as an exciting time and an evolution in ecological thinking, where innovation and experimentation were encouraged. As they built their program, they attended seminars, learned about ecological approaches and tried and tested new ideas. A team of older experienced and new young staff learned from each other, and they also listened and relied on the knowledge of the local community.

A series of OSMP area management plans from the mid to late 1990's, reflects the work of this team which was implemented to create dynamic, holistic plans that worked towards achieving multiple goals or co-benefits. And today, that first small group of innovators has grown to a whole team of ecologists, vegetation management specialists, sustainable agriculture experts and staff with other areas of expertise.

The ecological principles of IPM not only apply to insects and insecticides in agriculture, but to all organisms and all types of pesticides - including weeds/herbicides, fungal diseases/fungicides, nematodes/nematocides etc. IPM can be implemented successfully in buildings and structures, residential yards, forests, and prairie ecosystems at different scales.

In the early 1990's, OSMP staff participated in cross-departmental teams where people shared ideas. Staff from the Parks & Recreation were starting to explore sustainable landscaping practices. The public was also concerned about pesticide use, air quality and other environmental issues and asked council to take action. The city manager's office responded to this momentum from multiple fronts and the  first IPM policy was enacted in 1993 . The policy built on the foundation that city staff had created and included the cutting-edge approach of Robert van den Bosch and other scientists who developed the process for ecologically-based IPM. The city's IPM program has evolved since the first IPM policy was adopted in 1993. The next story map describes the updates and changes to Boulder's program and some of the driving forces that precipitated updates.

Next: Part 3 -  Evolution of Boulder's Integrated Pest Management Program  Previous: Part 1 -  Introduction to Boulder's Integrated Pest Management Program