Welcome to the fascinating world of Biological Control! If you’ve just begun your journey as a new Scout or IPM Specialist, you might be feeling a bit overwhelmed by the amount of information being thrown your way and the responsibility that comes with applying that information.
Your journey ahead is filled with opportunities for growth and learning, therefore understanding biological controls (biocontrols for short)—a key component of pest management— will make a world of difference in your confidence and effectiveness. By mastering the basics, you will set yourself up for success and ease those initial jitters. In this blog post, we will break down four essential things you need to know about biocontrol. Let’s dive in and uncover the knowledge that will empower you to become the hero your farm needs!
1. Understanding Biocontrol: The Basics
You may be confused as to what others are referring to when they say “good” bugs, biologicals, beneficials, biocontrols, or bios. All of these terms describe the beneficial insects that are naturally found or are placed into a crop to reduce pest populations.
Biocontrols are a natural method of managing pests by using other living organisms to keep them in check. Unlike chemical pesticides, which can have harmful side effects on the environment and non-target species, biocontrols are an eco-friendly alternative.
There are many new technical terms that you will learn as your experience and knowledge grows, but there are 3 crucial terms that are important to learn and understand:
Establishment, refers to the successful introduction, adaptation, and long-term survival of a biological control agent in a new environment, such as your crop, where it can sustain its population and effectively control the target pest over time.
Pest Influx, refers to a rapid increase in pest population, often due to favorable environmental conditions, lack of natural enemies, or intrusion from outside of your greenhouse. A pest influx can overwhelm existing biological control measures and lead to outbreaks. Winged pests, such as thrips, often fly into a greenhouse through open, unscreened vents.
Outbreak, refers to rapid and uncontrollable surges in pest population, often surpassing the ability of biological control agents to keep it in check and leading to economic loss in the form of unmarketable produce, plants, and flowers. Outbreaks can be caused by a multitude of factors but are often driven by gaps in preventative measures.
2. Effective Biocontrol: The Three Approaches
There are three main types of biocontrol approaches for using natural enemies to control pest populations:
Conservation: Preserving or enhancing existing natural enemy populations already found in the crop. For example, preserving Orius insidiosus populations with Banker Plants like Alyssum Lobularia maritima, or Purple Flash Ornamental Pepper Capsicum annuum.
Augmentation: involves increasing natural enemy populations by releasing more into the crop to control pests more effectively. For example, increasing Amblyseius swirskii population numbers to control thrips through weekly applications.
Classical: introduces natural enemies from the pest's native region to provide long-term control of invasive pests. A historical example in Canada is the introduction of the parasitic wasp Trichogramma minutum to control Spruce Budworm Choristoneura fumiferana.
For the rest of this blog post, we will be focusing our tips on Augmentative Biocontrol, as it is the most common type you will encounter as a Scout or IPM Specialist.
3. Types of Biocontrol Agents: Predators, Parasitoids, and Pathogens
Biocontrol species fall into three main categories: predators, parasitoids, and pathogens. Each plays a unique role in pest management, and knowing the differences will help you identify and utilize them effectively.
Predators: Predators are organisms that hunt and feed on other organisms. In the world of biocontrol, they are beneficial insects or mites that consume pests. At Crop Defenders we locally produce predatory mites and predatory insects that can help protect your crop.
Here are three examples of commonly used predators:
Amblyseius swirskii (Predatory Mite):
Amblyseius swirskii commonly feed on thrips larvae and whitefly larvae and eggs, but are also known to feed on Spider Mites.
It is important to note that these mites do not perform well in cooler temperatures, so environmental conditions must be considered before their application to ensure optimal performance.
Orius insidiosus (Predatory Insect):
This tiny insect, also known as the Minute Pirate Bug, are commonly used to control thrips.
Orius insidiosus adults and nymphs feed by piercing thrips larvae and adults with their mouthparts and sucking out the contents, leaving an empty skin.
They are very sensitive to chemical sprays, and residues can inhibit their performance and establishment. They diapause and are not active in conditions where photoperiods are less than 12 hours.
Amblyseius cucumeris (Predatory Mite):
Amblyseius cucumeris commonly feed on thrips larvae in greenhouse crops, and feed by piercing their prey with their mouthpiece. They can also prey on Cyclamen Mites Phytonemus pallidus and Broad Mites Polyphagotarsonemus latus.
Although they are not as aggressive as Amblyseius swirskii, the cost per mite is generally lower, therefore they can be applied in the crop at higher rates for less comparative costs.
It is important to note that these mites do not perform well in hot temperatures, so environmental conditions must also be taken into consideration to ensure optimal performance.
Parasitoids: Parasitoids are insects that lay their eggs on or inside other insects, and some may also feed on pests. When the eggs hatch, the larvae feed on the host, ultimately killing it. The larva develops inside of the host, converting the host into a “mummy”, where a new adult will emerge from.
Parasitoids are specialists, meaning they target specific pest species. At Crop Defenders, we locally produce two commonly used species of parasitoids:
Aphidius Colemani:
Aphidius colemani is a parasitoid wasp that targets small aphid species including Green Peach Aphids and Cotton-Melon Aphids.
Aphidius evri:
Aphidius evri is another parasitoid wasp that targets larger aphid species including Potato Aphids, Foxglove Aphids, and Cannabis Aphids.
Both Aphidius colemani and Aphidius ervi use alarm signals emitted by the plant (known as volatile organic compounds) and/or signals emitted by the aphids (known as kairomones) to search and find where the aphids are present in the crop.
Pathogens: Pathogens are entomopathogenic (insect-killing) microorganisms, so you are unable to see them with your eye, that cause disease in pests. They include nematodes, bacteria, viruses, and fungi. One common type of pathogen used in biocontrol is the nematode species Steinernema feltiae.
Steinernema feltiae:
These microscopic worms will enter thrips pupae and fungus gnat larvae, and infect the host bacterial pathogens, ultimately killing them.
Steinernema feltiae reproduces in pest cadavers, and thousands of juvenile nematodes then emerge into the growing media, searching for their next hosts.
They are particularly useful in controlling soil-dwelling pests, and are most effective when applied as a drench to soil-based and coco coir growing media. In order for the nematodes to search for hosts, there must be adequate moisture content. For this reason, nematodes are not recommended when growing in stonewool.
Steinernema feltiae can be applied with Stratiolaelaps
scimitus (Hypoaspis) or Dalotia coriaria (Atheta) to achieve greater control of thrips pupae and fungus gnat larvae.
4. Identifying and Monitoring Biocontrol Agents
As a Scout or IPM Specialist, your ability to accurately identify and monitor biocontrol agents is crucial. Each bio has specific characteristics and requirements, and knowing these will help you determine if they are working effectively. By monitoring your biocontrols, you can assess their performance and generate crucial data for your farm's decision-making.
Here are 3 tips for accurate identification:
Learn Key Characteristics: Familiarize yourself with the physical features of each biocontrol agent your farm commonly uses.
Use Tools and Resources: Employ a magnifying hand lens for accurate identification in the crop, or take samples to identify under a microscope. Identification guides and online resources can also be helpful.
Regular Monitoring: Set up a consistent schedule for monitoring biocontrol agents. Check their numbers, activity levels, and the presence of pests they are supposed to control.
Conclusion
Embarking on your journey as a Scout or IPM Specialist is an exciting opportunity to make a tangible impact towards the success and growth of your farm. By having a strong understanding of the basics of biocontrols—what they are, the types available, how to identify and monitor them—you will build a solid foundation of knowledge for your role.
Mastering these basics will not only boost your confidence, but also enhance your effectiveness in managing pests naturally and sustainably. Remember, even the most experienced IPM Managers and Consultants all started where you are now. With curiosity, continuous learning, and practice, you’ll soon find yourself navigating the world of biocontrols with ease. Embrace the learning process and let your knowledge guide you to success in your career.
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