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Biological vs. Chemical Pest Control: Benefits and Disadvantages

Linda Crampton is a science writer who is interested in environmental issues. She is very concerned about the harmful effects of pollution.

Pest control protects fruit.

Pest control protects fruit.

The Pest Problem

All living things strive to survive, but unfortunately the needs of other creatures sometimes conflict with our needs. An example of this conflict is the struggle between pests and humans. Pests are creatures that injure or kill plants or domestic animals, transmit disease, cause economic damage, or are a nuisance in some other way. They eat our food crops or ornamental plants, infect plants that are useful to us, make us sick by transmitting infectious organisms, infest our livestock and pets, and destroy property. An effective form of pest control is essential if we're going to win the battle with the creatures.

Many different chemicals are used to kill pests. These pesticides often work well, but since they're designed to kill living things they may cause serious problems in humans or pets. Pesticides contaminate the environment and the food that we eat and may enter our bodies when we're applying them to our plants or animals. They sometimes harm other organisms in addition to their target. Another problem with using chemicals to control the population of an organism is that a pest may become resistant to a pesticide.

Biological control involves the use of another living organism to kill a pest. No chemicals are needed, there is no environmental contamination with pesticides, and the pests don’t become resistant to the control method. However, introducing a plant or animal to an area where it doesn’t normally occur can create new problems. Biopesticides are on the borderline between biological and chemical control and may be useful.

Strawberries are one of the produce types likely to harbour pesticides.

Strawberries are one of the produce types likely to harbour pesticides.

Types of Biological Pest Control

Three types of biological pest control exist. In classical biological control, natural predators, parasites, or pathogens of a pest are imported into an area to protect a crop or livestock. A "pathogen" is an organism that causes disease. Importation can be a useful strategy when the pest has been introduced from another region and has no predators in its new habitat.

In conservation biological control, no new plants or animals are introduced to an area, but the environment is manipulated to favor the survival of local enemies of the pest. For example, a farmer or gardener may provide additional food sources or suitable habitats for a pest's enemies.

In augmentation biological control, plants and animals that control a particular pest and are already present in an area are increased in number by inoculation or inundation. Inoculation is the introduction of relatively few organisms. Inundation involves the introduction of a very large number of organisms.

Spinach occupies the second position in the Dirty Dozen list created by the EWG.

Spinach occupies the second position in the Dirty Dozen list created by the EWG.

Advantages of Biological Control

Biological pest control has some distinct advantages compared to the chemical process. Farmers and gardeners don’t have to worry about poisoning themselves, their families, or their pets when they treat their crops or plants. There are no toxic chemicals to store and no concerns about children or animals discovering the stored pesticides. There are no pesticides to give off dangerous vapors, accumulate in the soil, or collect in water. The food that's produced will be free of pesticides (or low in pesticides, since the food may have picked up chemicals distributed by other people).

Disadvantages of the Process

Despite the appealing advantages of biological pest control, there may be important disadvantages to the activity. Artificially increasing the population of a certain predator may have unforeseen consequences. In addition, an organism that has been introduced from another area to destroy a pest may become a pest itself, especially if it has no natural predators in its new habitat.

A famous example of this effect is the introduction of the cane toad into Australia. In 1935, cane toads were transported from Hawaii to North Queensland. The goal was for the toads to catch and eat the beetles that were attacking the sugar cane crops. Not only was this plan unsuccessful (the toads couldn't jump high enough to reach the beetles on the sugar cane stalks), but the cane toad has now become an invasive species. The toads have spread to new areas and have a thriving population. They feed on native animals, and the toxin in their bodies often kills their potential predators.

Fortunately, previous experiences have taught researchers how to better assess the likelihood that an introduced predator, parasite, or pathogen will cause a problem. Nature's behavior can't be completely predicted, however, and scientists never know for certain what will happen when they introduce a plant or animal to an area.

Biological pest control often takes longer to work than the chemical method and frequently reduces a pest population to a low level rather than eliminating it completely. These facts may be considered a disadvantage by some people. Once a predator population is established, however, biological pest control will operate on its own without the need for further human input (as long as the predator survives).

Pest control methods must be safe for livestock, such as these chianina oxen.

Pest control methods must be safe for livestock, such as these chianina oxen.


Biopesticides are chemicals, but they are produced from or by living things and are considered to be safer for humans than chemical pesticides. That being said, new discoveries are constantly being made by scientists. They may well discover new information about all types of pesticides in the near future.

Three types of biopesticides currently exist—microbial pesticides, plant-incorporated protectants (or PIPs), and biochemical pesticides. I describe each of them below.

Microbial Pesticides

Microbial pesticides are made from microorganisms, such as bacteria or fungi, which are used to infect and kill pests. Although the microbes are said to form a pesticide, their use is actually an example of biological pest control.

A popular microbial pesticide is the bacterium called Bacillus thuringiensis, also known as Bt. Different strains of Bt exist, each producing a distinct mix of proteins. Some of these proteins kill insect larvae. Different proteins kill different species of insects.

Plant-Incorporated Protectants or PIPs

PIPs are chemicals made by plants that have been genetically altered in order to produce a particular pesticide. For example, the Bt genes that make pesticide proteins can be inserted into plants. The genes become active and the plants produce their own pesticide, which kills insects that try to eat the plant. The pesticide proteins appear to be harmless to humans. The effects of PIPs are tested before farmers can use them.

Ornamental plants are beautiful, unless they're being attacked by pests.

Ornamental plants are beautiful, unless they're being attacked by pests.

Biochemical Pesticides and Semiochemicals

Biochemical pesticides are non-toxic (or almost non-toxic) chemicals made by living creatures. They are usually the only kind of pesticide that organic food producers are allowed to use. A biochemical pesticide's job is to control a pest, but it may not kill the organism directly.

Semiochemicals are chemicals released by living things that influence the behavior of other organisms. A pheromone is a semiochemical that affects a member of the same species as the organism that made the pheromone. Insect pheromones attract other insects, which may be insects of the opposite gender or insects of both genders, depending on the pheromone. Pheromones can be used by farmers to lure insects into a trap.


Pyrethrins are another type of biochemical pesticide. They are made in the seed cases of a type of chrysanthemum and kill insects by damaging their nervous systems. Unlike some chemical pesticides, pyrethrins quickly break down in the environment and are said to be non-residual chemicals. They have low toxicity to humans and other mammals but should still be treated with respect. It's important to realize that just because a chemical is natural doesn't automatically mean that it's completely safe for humans. Still, pyrethrins are considered to be some of the safest chemicals to use as pesticides. They are toxic to fish and bees, however.

A substance called piperonyl butoxide is often added to pyrethrin insecticides. Piperonyl butoxide has no ability to kill insects by itself but is still a helpful substance. It makes the insecticidal ability of pyrethrins stronger by stopping an insect's body from breaking the chemicals down.

Kitchen Ingredients That May Remove Pests

Some common kitchen substances may be useful for getting rid of garden pests and may be worth trying before another method of control is used. For example, a canola oil spray is sometimes used as an insecticide yet is non-toxic for humans. It shouldn't be sprayed near water, however. Garlic is said to repel birds and insects and also degrades quickly. Black pepper oil is used to repel mammals. Although it may not be a common household product in some countries, neem seeds and the oil from the seeds are used to create a natural pesticide that kills many insects.

Chili peppers are chopped and then soaked in water for a day to make an insecticide. Some people add a small amount of soapy water to the chili water to make a spray that will stick to plants. Try to use a soap or detergent that is safe for the environment and for the plants if you do this. Be careful if you use chili peppers, since they can burn and irritate skin and mucous membranes.

Types of Chemical Pesticides

Chemical pesticides are synthetic substances that are created to kill or injure pests. They can be classified in several different ways. For example, pesticides may be categorized based on when they begin to work after they are applied. Contact pesticides kill a pest shortly after touching the surface of its body. Systemic pesticides are absorbed by plants or animals and must spread through the inside of their bodies to untreated areas before they can kill the pests. The pesticides may travel through the whole body or just to one particular area in the body.

Pesticides may also be classified based on how they work. Desiccants remove water from the bodies of plants or animals, for example, and defoliants cause plants to drop their leaves. Insect growth regulators kill insect larvae by interfering with the process in which juvenile insects molt and turn into adults.

Although most pesticides kill the pests that they attack, not all of them do. Repellents simply repel pests, as their name implies. An example of this type of pesticide is DEET, a common substance in personal insect repellents. Sterilizing agents interfere with the ability of the pest to reproduce, but they don't kill the creature that they affect.

Additional ways to classify chemical pesticides are by the type of organism that they are designed to kill, as the table below shows, or by their molecular structure.

Classifying Pesticides According to Their Target

Pesticide TypeTarget Pest


nematodes (roundworms)


slugs and snails



acaricides (or miticides)

fleas, ticks, and mites















Peeling fruit removes some types of pesticides but not every type.

Peeling fruit removes some types of pesticides but not every type.

Potential Problems for Human Health

Chemical pesticides are potent substances designed to destroy pests. They may harm us, too. This harm is generally reduced because farmers often have to follow strict laws about pesticide use. These laws include rules about allowable pesticide levels on crops and about storage, transport, and application of the chemicals. Despite all the regulations, however, we do ingest pesticides in our foods and drinks, inhale them from the air that we breathe, and absorb them through our skin.

The agencies that regulate pesticides usually admit that chemical pesticide use does involve safety risks, but they say that these risks are acceptable considering our need to protect agricultural crops and feed people. Many individuals disagree with the idea that the risk is "acceptable", however. The agencies also claim that most people are exposed to only small amounts of pesticides in their daily lives. However, if a pesticide is very toxic a small amount can be dangerous.

Fruit with blemishes is often safe to eat.

Fruit with blemishes is often safe to eat.

Possible Effects of Pesticide Poisoning

The effects of a pesticide on the human body depend on several factors, including the nature of the pesticide, the amount of chemical involved, the length and frequency of exposure, and the age of the person being exposed to the chemical. Children are especially susceptible to the effects of chemicals because of their small size and the fact that their bodies and nervous systems are still developing.

Symptoms of acute pesticide poisoning develop immediately or shortly after exposure to a dangerous dose of the chemical. The symptoms may be relatively minor, such as a headache, dizziness, nausea, and diarrhea. More serious symptoms include vomiting, abdominal pain, a rapid pulse, lack of muscle coordination, mental confusion, inability to breathe, burns, loss of consciousness, and even death.

Other possible effects of pesticide exposure may take longer to develop. It's hard to definitely prove that a pesticide is responsible for a human disease, but some types are suspected of causing nervous system damage or cancer.

Beautiful and flawless flowers are lovely to see, but the use of a pesticide to keep them that way needs to be considered very carefully.

Beautiful and flawless flowers are lovely to see, but the use of a pesticide to keep them that way needs to be considered very carefully.

Common Types of Insecticides and Their Dangers

Many pests are insects and so most pesticides are insecticides. Important types of insecticides, which are classified based on their chemical structure, are organophosphates, carbamates, organochlorines, pyrethroids, and neonicotinoids.


Organophosphates kill insects by interfering with the activity of their brains and nervous systems. Unfortunately, they can also affect the nervous systems of humans and other animals. They do this by altering a normal process involving acetylcholine, a common neurotransmitter. Neurotransmitters control the transmission of a nerve impulse from one nerve cell to the next. They are normally broken down or removed once they've done their job. Organophosphates interfere with the action of acetylcholinesterase, the enzyme that breaks down acetylcholine.


Carbamates are also used as insecticides and work in a similar way to organophosphates. They break down quicker and are considered to be less dangerous to humans, however.


The most famous organochlorine is DDT (Dichlorodiphenyltrichloroethane). It has been banned in several countries for decades, except for very specialized use, but it is a very persistent pesticide. "Persistent" pesticides stay in the environment for a long time and don't break down. DDT is still found in soil and in the bodies of animals and humans. DDT thins the shells of bird eggs, causing the developing babies to die. It also disrupts our endocrine systems (which produce the hormones that we need) and is thought to damage genes and increase the risk of cancer.


Pyrethroids are synthetic chemicals derived from pyrethrins. Like pyrethrins, their use is increasing because they are considered to be less toxic than the other categories of insecticides.


Neonicotinoids are derived from nicotine, a plant chemical. They interfere with a pathway that is common in the insect nervous system and are suspected of playing a role in honeybee colony collapse disorder.

Rhododendrons can be lovely even when not treated with pesticides.

Rhododendrons can be lovely even when not treated with pesticides.

Integrated Pest Management or IPM

Due to the concerns about chemical pesticide safety, some communities are now using integrated pest management techniques to control pest problems. Integrated pest management, or IPM, involves the use of multiple techniques to solve a problem as safely as possible. These techniques include:

  • using physical or mechanical protection methods, such as picking pests off plants, creating barriers to block them from entering an area, and removing clutter
  • choosing an appropriate garden or field design, such as choosing companion plants that protect a desired crop
  • changing soil composition or growing conditions to discourage pests
  • using specific techniques to prevent invasions by particular pests, such as fixing water leaks, storing wood in a dry location, and preventing tree or shrub branches from touching buildings
  • using biological control methods and applying biopesticides
  • applying chemical pesticides if these are absolutely necessary

Some Good News

The good news is that public pressure and human health concerns are stimulating some communities and individuals to use safer methods to manage pests. These methods include physical control, biological control, the use of biopesticides, and, if necessary, the use of safer chemical pesticides. Some local governments have even stopped using pesticides on ornamental plants and lawns for purely cosmetic reasons. In addition, some people are now willing to accept fruit that hasn't been treated with chemical pesticides and looks less than perfect, provided it's safe to eat. I hope these strategies for avoiding harmful chemicals become very popular.

References and Resources

© 2012 Linda Crampton


Linda Crampton (author) from British Columbia, Canada on March 30, 2019:

If you read the article again, especially the section called "Advantages", you'll see some benefits of biological control.

Salah on March 25, 2019:

I need The Reason Why biological control is better than chemical control in the control of pests and parasites

Linda Crampton (author) from British Columbia, Canada on June 06, 2018:

Thank you. I think it definitely is a topic for discussion.

Linda Crampton (author) from British Columbia, Canada on June 24, 2017:

Thanks for the comment, gokul. I'm glad the article was useful for you.

Linda Crampton (author) from British Columbia, Canada on May 26, 2017:

I'm glad you find the site useful, Mohammed.

Mohammed on May 25, 2017:

l am very very great tanks to this website. I will be get many more references for the future. sincerely yours...

Linda Crampton (author) from British Columbia, Canada on November 12, 2015:

Thanks for the visit and the great comment, breathing. Like you, I always prefer natural products whenever I can use them.

TANJIM ARAFAT SAJIB from Bangladesh on November 12, 2015:

There are always possibilities of diseases with chemicals. That's why I prefer natural pesticides over the chemical ones. Yeah there are cases where you can get great results with the chemical pesticides but there are always chances of great destruction too! That's why if you are ever bound to use chemical pesticides don't do anything on your own. Try to take the suggestion from experts. If possible try to perform the whole process taking the expert along with you. After all it will not take you years to do so!

Overall a great and informative article about the different kinds of pesticides and their uses.

Linda Crampton (author) from British Columbia, Canada on May 28, 2012:

Thank you very much for both the comment and for voting, twinstimes2!

Karen Lackey from Ohio on May 28, 2012:

Well done, Alicia. I learned quite a bit reading your hub. Both useful and interesting...and voted up!

Linda Crampton (author) from British Columbia, Canada on May 24, 2012:

Hi, theraggededge. Thank you for the visit and the comment. It's good that we have some natural pesticides to choose from instead of having to rely on chemical ones!.

Bev G from Wales, UK on May 24, 2012:

Wow - so much information! I like the natural insecticides you suggest and have used one or two of them but didn't know about the others. Many thanks.

Linda Crampton (author) from British Columbia, Canada on May 23, 2012:

Thank you for the comment, Karen! I'm lucky to have a garden, so I grow some fruits and vegetables there, without chemical control. A large part of the garden is used by my dogs, though, so I still have to buy a lot of produce. I try to buy organic food whenever I can.

Karen Creftor from Kent, UK on May 23, 2012:

Very useful and well researched hub, thanks Alicia!

I don't have a garden myself but I do try to buy organic, mainly due to being highly sensitive to chemicals and heavy metals. It's good to know what goes on in our food production.

~Kaz x

Linda Crampton (author) from British Columbia, Canada on May 19, 2012:

Thank you for the visit and the comment, drbj. It is interesting - and a little scary - to think that substances that we eat have the power to kill insects!

drbj and sherry from south Florida on May 19, 2012:

Fascinating information and thorough research, Alicia. But now thanks to your edifying description of chili peppers potential use as insecticide, I am swearing off chili peppers. Promise.

Linda Crampton (author) from British Columbia, Canada on May 18, 2012:

Thanks for the visit and for commenting, teaches. I use natural remedies, too! They work in my garden.

Dianna Mendez on May 18, 2012:

I am going with your natural remedy approach. It would be a better world for all of us without those harmful chemicals that have the potential to cause severe reactions. Thanks for posting.

Linda Crampton (author) from British Columbia, Canada on May 17, 2012:

Thank you very much for the comment, chrissieklinger! I appreciate your visit.

chrissieklinger from Pennsylvania on May 17, 2012:

I might just try that chili pepper spray mixture. Loved reading this hub...thanks for all the information!

Linda Crampton (author) from British Columbia, Canada on May 17, 2012:

Thank you very much for the votes and for sharing the hub, Peggy! It is scary to think about the pesticides in our bodies and their possible effects. It's certainly time for individuals and communities to think very carefully about what forms of pest control to use.

Peggy Woods from Houston, Texas on May 17, 2012:

Hi Alicia,

It is a perennial problem for farmers of all types...commercial concerns as well as backyard gardeners. I am happy to see the movement towards using more natural pesticides and plants that can be grown together for best effect. The old saying..."we are what we eat"...includes the pesticides used! Excellent hub. Up votes and SHARING this.

Linda Crampton (author) from British Columbia, Canada on May 17, 2012:

Hi, Tom. I'm very glad that more people are thinking about safe ways to control pests, too. There are still a lot of potentially dangerous chemicals being used as pesticides, though. Thank you for the comment and the votes. I hope that you have a wonderful weekend as well!

Linda Crampton (author) from British Columbia, Canada on May 17, 2012:

Hi, Danette. Yes, the web of life is very intricate and there is still so much to learn about how nature works. I agree with you - we may never be able to control the environment and the connections between living things! Thank you very much for the comment and the share.

Thomas Silvia from Massachusetts on May 17, 2012:

Hi my friend, has always i love reading your hubs, it is so nice to hear that they are trying to find better ways and safer ways to manage pests in order to protect us,our pets and our food supply.

Vote up and more !!!

Have a awesome weekend my friend !

Danette Watt from Illinois on May 17, 2012:

Hey Alicia, I have to agree with mwilliams66. I had a questions/comment about introducing a predator to control a pest (that it wasn't always a good idea) and you addressed that with the toads in Australia. When will we learn that we can't always (maybe never?) control the environment/chain of life.

There was a lot of info here to absorb and I'll have to come back to reread it but as always, I enjoyed your writing and I'm going to share it on Google+

mwilliams66 from Left Coast, USA on May 16, 2012:

Thanks Alicia. I'm working up to it. I'm doing a lot of reading and commenting right now. I'm really enjoying that. I have found that your hubs are some of the most interesting.

Linda Crampton (author) from British Columbia, Canada on May 16, 2012:

Thank you very much, mwilliams66! I appreciate your comment. I'm looking forward to reading your hubs!

mwilliams66 from Left Coast, USA on May 16, 2012:

As with all the hubs written by you that I have so far read, I found this to be a very interesting article.

All the questions that came to mind as I read, were answered.

Very thorough and useful.