Biological pest control

Biological Pest Control Basics

Written by Mike Bonds

Biological pest control
Lady beetle, by Scott Bauer. (Wikimedia Commons)

Managing pests is an important part of cultivating plants whether you are tending a small garden in your yard or several fields of crops. Insect predators can make short work of healthy plants, particularly if insect predators are in abundance. The good news is that there are natural ways to combat these pests that growers have been utilizing for many years. Granted, not all solutions are created equal. There are a number of reasons why biological control efforts may fail; including breeding being out of sync or the countermeasure not being strong enough.
The primary points of biological pest control are:

  • Classic Biological Control
  • Conservation
  • Augmentation

Each offers its own pros and cons with success hinging on a large number of factors that is impossible to completely define. Even still, these methods have traditionally been effective for a number of growers and have been used since the dawn of farming.

Classic Biological Control

There are times when the local ecological system gets out of balance. In particular, a pest may be introduced from an outside source and thrive in the new locale. These pests are typically referred to as “exotics”. Exotics are a dramatic problem in several nations to the point that strict regulation is put on the import of any new species.
The problem with exotics is that natural predators in the area may be non-existent. There is no counter-balance to their presence. To combat these, some growers will introduce predators in the local area to help curb pest numbers.
Important factors must be calculated into this strategy. The predator that is being introduced must be carefully scrutinized to ensure it will not become an exotic pest itself. What else will that predator attempt to eat? What could happen if it runs out of prey? How does it reproduce? Does it interfere with the local eco-system? This is especially difficult when considering hedgehog cage requirements for indoor set ups. This small and tight places are much harder to control than a small piece of land.
On the positive side, this method is very effective when done correctly. One of the earliest successes took place in California in the late 1800’s. The cottony cushion scale was decimating citrus crops until the Australian vedalia beetle was introduced as a counter-measure. After a few years, the cottony cushion scale was under control and the citrus industry was recovering.
Classic Biological Control is typically low cost and low maintenance. After the initial investment for the pests, there isn’t really any other maintenance or costs associated with the method.
Here is a video about biological pest control in organic tree crops by Nick Mills at UC Berkeley that explains more.


A relatively simple and effective way to prevent damage from pests is to preserve the natural habitat of the local predators. Local predators are already adapted to the area habitat and function well enough to maintain their numbers. A grower can help maintain that predator through careful action. You should check what insects and plants any chemicals could effect. The predators may be susceptible to general applications of certain chemicals.
Many chemicals come in engineered strains. In the event that you need to fall back on their use, you will want to find a specially engineered solution that will attack the problem and not the positive contributors. Additional plantings may also be in order to create more available space for the predator if they have any particular likes.
It is unfortunately common for farmers to unleash insecticides on their crops or garden without due diligence of the impact on the other insects in the area. Unfettered use of chemicals is theorized to be one of the contributing factors behind the honey bee Colony Collapse Disorder.


The process of augmentation is a large scale effort to enact a change in the local eco-system. This could be a massive planting of a certain type of plant or controlled releases of predators to take up residency. Releases can be smaller and controlled or large and inundating. Controlled releases typically take place during the optimal time for the predator to make a snack of their prey. For example, if the predator is an egg parasite, you would want to release those predators when the prey actually has eggs gestating. An inundating release takes the opposite approach and “carpet bombs” the area with millions of the predatory insects. Neither approach is necessarily wrong.
Augmentation may also include the introduction of new plants in the area that are more delectable to the pest. The pest will then attack those plants instead of going after the more valuable crop. This method can be problematic if done incorrectly. You wouldn’t want to include a plant that attracts different pests to feast on the new dinner offering!
Small scale commercial and home gardens can utilize augmentation by lining their gardens with different plants attractive to pests. Be certain to do your research if you want to go this route. Plant diseases can be transmitted to your garden if any of your new plants happen to harbor them.

The Positivity of Biological Control

When done right, biological control can help protect valuable plants and keep pests at bay. These methods have been in use in some form or another for as long as people have been farming. Putting them to use in your fields or garden can thwart those nasty pests that will destroy your plants. Just remember to perform diligent research on your target and the instrument you intend to use before implementing it.

Written by Guest Expert

Mike Bonds is a green technology advisor for an environmental and pest management firm based in New York City. He enjoys finding alternative approaches to traditional methodologies and also has a big respect for ants.


  1. The problem here is you haven’t said anything beyond the abstract and the theoretical. It’s just that feel-good “natural” stuff all over again.
    Here is a partial list of pests that regularly show up on our little farm:
    Plum curculio
    scab fungus
    codling moth
    apple maggot
    Colorado potato beetle
    Japanese beetle
    downy mildew
    cucumber beetle
    squash vine borer
    round-headed borer
    tomato hornworm
    flea beetle
    marmorated stink bug
    tarnished plant bug
    cabbage looper
    Not to mention voles, woodchucks, deer, and porcupines.
    Which happy little green “organic pest control” do you recommend?

  2. This article didn’t provide a lot of details. The video shows how complicated this can be even in one sector of agriculture, so it’s understandable that this topic would fill volumes to cover thoroughly. But I found it refreshing in the context of this blog. Biological pest control is far more challenging than simply using GMOs and pesticides. It would be great to see more financial support for implementing and researching this sort of IPM in US agriculture, as opposed to a speed up of the chemical treadmill.
    Thanks biofortified

  3. Mlema, There will be more funding when folks such as my self decide such methods may be cost effective and decide to buy and try. The insects, of course, will trip over ways to defeat some of these as well. I have looked at a few methods and am considering. Any disease or fungi I use may be susceptible to resistance and may also lend itself to G.E. use. Local circumstances can effect these products, Predatory insects often fly away if used in fields. My wild guess is that we will see more use of these principles on farms and in G.E. Hopefully we won’t just be enlarging the treadmill. More likely we will, but at least this approach represents more available tactics that we may be able to rotate.

  4. Mr. Wee, For the mammals try grinding up a few of the most vicious hot peppers you can find with some hot water. Let stand for at least a few hours. Strain through an old washrag into a sprayer and then blend up egg whites and pour this into a sprayer. Spray your plants especially the underside of the leave. Deer and most mammals will learn quickly to avoid eating such plants. As they learn I’ve found I don’t need to spray the whole area every time. They seem to understand the smell of the peppers. Please try to learn more about this as I believe there is some potential there. More so with some of your pests than others. And if you find a source of Nosema Locustae please let me know.

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