Harnessing the Power of Bacillus Thuringiensis Israelensis for a Healthier Garden (Bti)

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It can be difficult to keep your garden healthy and vibrant. Insects and other pests and diseases not only threaten the well-being of your plants, but they can also cause you quite a bit of annoyance, grief, and exposure to disease. 

So how can you control pests such as black flies, mosquitoes, and fungus gnats in your yard and garden? 


Luckily, the beneficial bacterium, Bacillus thuringiensis israelensis (Bti) can be harnessed to protect you and your garden from these harmful insect pests. 

In this article, we will explore the power of Bti and compare and contrast it with Bacillus thuringiensis kurstaki (Btk). 

We will also provide sound advice on how these powerful Bt products can be used to create a healthier garden environment. Read on to learn more.

Bti vs. Btk

Bacillus thuringiensis (Bt) is a soil bacterium that occurs naturally. It was originally discovered in Thurin, Germany, over 100 years ago. 

It’s EPA-registered (Environmental Protection Agency), meaning this insecticide is approved for residential, environmental, and commercial settings and is safe to use around animals like mammals, fish, and birds when you follow the directions properly.

The bacterium’s active ingredient is fatal to several types of target insects in their larval stage. Although there are many different strains of Bt, we are most familiar with Bti and Btk, both specifically targeted pest control substances.

Understanding Bacillus Thuringiensis Israelensis (Bti)

Bti is a naturally occurring soil bacterium recognized worldwide as an effective biological control agent against the larvae of disease-carrying black flies and mosquitoes, as well as the destructive larvae of fungus gnats. 

Black flies lay their eggs in streams and rivers, so trained field technicians usually apply Bti to streams where their larvae are found. 

This is painstaking work because the technicians must monitor the pests closely and apply precise amounts of the bacterium in liquid form at the right time to target the larvae effectively. 

Bti does not linger in the environment, so the timing must be perfect for catching the larvae at a vulnerable stage and having the product present in the right amounts for an effective time, typically 24 hours. 

This bacterium produces protoxins in the form of crystalline protein toxin that is lethal specifically to the larvae of mosquitoes, fungus gnats, black flies, and some types of midges. This is because it has endotoxins that break down the skeletal muscles and cause the death of insects.

This helps in effectively controlling the mosquito population, especially those carrying diseases like dengue, Zika, and chikungunya.

Because of this selective toxicity, Bti is harmless to humans, animals, and beneficial insects like honey bees, butterflies, and ladybugs.

Make Your Garden A Healthy Hangout Without Mosquitoes & Black Flies

Mosquitoes and black flies aren’t just annoying. They also pose health risks as carriers of diseases. 

Bti can be a valuable tool in managing these pesky insects. Its application in standing water sources, such as ponds, bird baths, and rain barrels, can effectively target mosquito larvae. 

Bti disrupts these pests’ digestive systems, leading to their eventual demise. 

By incorporating Bti into your mosquito and black fly control strategy, you can significantly reduce mosquito populations without using chemical pesticides.

Why Does Bti Only Work On The Larvae of Black Flies, Mosquitoes, Fungus Gnats, and Midges? 

These particular pests have a specific combination of enzymes and an alkali gut. 

The spores contained in Bti interact with the gut of these larvae to produce toxins. This is what causes Bti to be fatal to these larvae and safe for virtually all other fauna. 

How Can You Use Bti In Your Home Garden? 

Although Bti is most effective when it is used for mosquito or black fly control on a community-wide basis, you can make good use of this valuable product around your yard and garden. 

Remember that Bti should be a part of a holistic Integrated Pest Management (IPM) plan. 

In addition to treating standing and running water on your property, you should also eliminate unnecessary or incidental standing water sources. 

  • Dump out water runoff under potted plants. 
  • Rinse and refill your pets’ water dishes daily. 
  • Clean and refill livestock troughs regularly and/or enlist the aid of mosquito fish or goldfish to eat larvae.

Bti dunks, pellets, granules, or liquids can be helpful for standing and running water that cannot be managed in these ways. 

You can purchase these Bti products at garden centers, online stores, or from pest control suppliers. 

Even though Bti is fairly harmless to non-target species, follow the manufacturer’s instructions for the appropriate dosage and application methods based on the targeted pests and the specific product you choose.

To use Bti against mosquito larvae, you would place specially prepared “mosquito dunks” in standing water where mosquitoes are known to breed, such as: 

  • Ornamental ponds
  • Disused pools 
  • Rain barrels
  • Fountains

It will kill off existing larvae within 24 hours without harming fish and other beneficial fauna. This naturally occurring soil bacterium has been safely used in mosquito control for over three decades. 

The dunks are safe, easy to use, and effective for up to a month in standing water. 

How Does Bti Control Fungus Gnats? 

It is common to find fungus gnats around houseplants and in greenhouses. Fungus gnats lay their eggs in soggy soil, and their larvae feed on fungus in the soil and plant roots, so the larvae can negatively impact your plants’ health while the gnats annoy you. 

To kill fungus gnat larvae, you can apply a liquid solution of Bti as a soil drench to plants infested with fungus gnats. 

For longer-term effectiveness, sprinkle Bti granules over the surface of the affected soil and water it in. 

You can repeat this treatment once every three weeks if necessary. The fungus gnat larvae will consume the Bti soil drench as they feast on fungus in the soil, and they will die. 

How to Use BTI As Organic Fungus Gnat Control

This treatment will not kill the gnats, but it will kill their offspring. Fungus gnats are ephemeral and will die off within a few days without intervention, but you can hasten their demise with a neem oil or insecticidal soap spray if you wish. 

It is worth noting that you can prevent fungus gnat infestation by avoiding overwatering. Fungus gnat larvae thrive in soggy soil. 

For this reason, in addition to treating existing fungus gnat larvae, you should adjust your watering methods and/or amend your soil for better drainage. 

You can also incorporate Bti granules into your potting soil mixture to help prevent future infestations. 

Understanding Bacillus Thuringiensis Kurstaki (Btk)

Btk is the strain that is most commonly used in gardening. It was the first available strain, often simply called Bt. 

It is effective against leaf-feeding caterpillars and can effectively defend your plants against hungry: 

  • European Corn Borer Larvae
  • Tomato Hornworms
  • Tobacco Hornworm
  • Tent Caterpillars 
  • Cabbage Worms
  • Fall Webworms 
  • Spongy Moths
  • Leaf Rollers
  • Bagworms
  • Loopers

This product works best on very young larvae that are feeding heavily. Applying Btk dust early in the springtime, just as larvae emerge, is most effective. The hungry larvae will feast on the leaves and the Btk.

How Does Btk Work? 

Btk works by paralyzing the caterpillars’ digestive systems with its inert ingredients. When this happens, the caterpillars stop feeding and die within a few days. 

Btk is a very safe pest control because it is only effective against caterpillar pests. It is safe for kids and pets and can be applied to food crops right up to the day of harvest. 

Be aware that Btk will kill butterflies and moth caterpillars, so don’t use it on plants intended to attract butterflies. 

Apply it to flowering fruit trees and shrubs after the blooms have faded to avoid negatively impacting beneficial pollinators. 

BTK – Prevents Worms from Destroying Your Fruit! 

How Do You Apply Btk? 

There are many commercial solutions of Btk in both dust and liquid formulas. The dust products are typically called Dipel, and the liquid products are typically called Thuricide. 

Choose the product that best suits your needs and follow the packaging directions closely. 

Can You Use Btk And Bti Interchangeably? 

Of the many types of Bt, each is pest specific. Btk is only effective against caterpillars that eat plant leaves. Bti is only effective against specific larvae in water or soil. 

Btk will not kill mosquito larvae or fungus gnat larvae. Bti will not kill caterpillars. Although both are quite safe to use, using the wrong product for the wrong purpose will only waste your time and money and result in plant damage and/or painful bug bites. 

Do City And State Governments Use Bti For Black Fly & Mosquito Control? 

Bti is widely used around the world for Black Flies and bacterial control of Mosquitoes. In fact, it has been used effectively in the vast rivers of Africa since the 1970s to control black flies. 

Local and state governments across the United States and worldwide use this safe, natural product to do away with the larvae of these disease-carrying biting insects. 

Are Bti Spraying Programs Safe & Effective? 

Many governments institute spraying programs; however, this may not be the most effective delivery method. This product targets the larvae of black flies, mosquitoes, and fungus gnats. 

Black flies and mosquito larvae hatch and live in bodies of water. Fungus gnat larvae live under the soil. 

For these reasons, products such as liquids, granules, briquettes, and dunks that deliver Bti directly to bodies of water are far more effective against black flies and mosquitoes than spraying would be. 

Likewise, liquid soil drenches or granules sprinkled on the soil and watered in would certainly be more effective against soil-dwelling fungus gnat larvae than sprays. 

Regarding safety, spraying Bti is fairly harmless to all concerned, including beneficial fauna, as well as humans, pets and wildlife and adult mosquitoes, black flies, and fungus gnats. 

In other words, there’s not much point in spraying Bti because it is ineffective against the adult forms of the pests it intends to control. Even so, some local and state governments do still have this sort of program in place. 

Can Bti Make My Garden Healthier? 

Although Btk is most commonly used in gardening to control caterpillars, Bti certainly has a place in helping you create a healthy garden free of annoying, disease-spreading, painfully biting black flies and mosquitoes, and unsightly fungus gnats. 

One of the significant advantages of using Bti and Btk in your garden is that these products are environmentally friendly. 

Unlike chemical pesticides that can persist in the environment and harm beneficial organisms, Bt products are targeted and have a short lifespan. 

These products break down quickly and naturally; selective toxicity ensures that non-targeted organisms remain unharmed. These qualities foster a balanced and healthy ecosystem in your garden.

Bti and Btk are compatible with organic gardening practices and other natural pest control solutions. 

By creating an Integrated Pest Management (IPM) system harnessing the power of Bti, Btk, and other natural products, you can minimize your environmental impact while effectively controlling garden pests.

Bacillus thuringiensis israelensis (Bti) and Bacillus thuringiensis kurstaki (Btk) provide a powerful and sustainable solution for gardeners seeking to protect themselves, their pets, and their plants from harmful pests. 

The selective toxicity of Bt, along with its environmentally friendly nature and compatibility with organic gardening practices, make Bti and Btk valuable tools in promoting a healthier garden ecosystem.

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