Pest Resistance: What To Do When Insecticides Fail

This article is a professional DIY guide to learning the reasons as to why bugs become resistant to insecticide products or show up after treatments. Using the suggested products and methods listed throughout this article helps homeowners to lessen the presence of insects in their property without needless applications.

Follow this easy to use guide and the suggested products and steps by our pest control experts to increase effectiveness of insecticides and decrease presence of insects after applications.

Insecticides are widely used to control indoor or outdoor insect populations in various settings, but often homeowners come across some form of pest resistance or continual activity after application. Unfortunately, there is no such thing as an insecticide that truly eliminates all pests in one treatment. It's going to take multiple applications and research to fully control insect populations and activities.

Failed insecticide treatments usually falls under two broad class of reasons.

1. Routine errors, which can cause failure to control insects and their activities. Insecticide applications can fail because of the wrong active ingredient used, treatment rate, or ph solution. Mistakes can also be made in the mechanical setting of the pesticide equipment being used. For example, using the incorrect spray pressure or volume, inappropriate spray nozzles, or making applications when weather conditions effect the spray distance or adherence to labeled surfaces.

2. The pest has developed resistance to the active ingredient being used in the product. When pests reproduce, they pass along the genes that helped the current population survive to their offspring. These reproductive activities continually provide an on-going pest infestation, even when the current adult insect has been eliminated.

There is always a risk of resistance, especially when the insecticides are misused or over-used. By following along with this guide, you can prevent or delay the development of resistance, and avoid insecticide failure.

What Causes Insecticide Resistance?

To confirm resistance, it should be observed if the insecticide is being used more frequently or consistently replaced.

There are several ways pests can become resistant to pesticide products, and they often will display more than one of these characteristics at a time.

Behavioral Resistance- Insects can detect products and areas with danger, and then work to avoid these areas all together. You may see pests cease feeding if they come across certain products that have been previously used.

Pests may also move to a different area that has not been sprayed, such as the underside of treated foliage or underneath yard debris. Cracks, crevices, voids, and dense vegetation also assist behavior resistance due to pests potentially moving further into these areas to escape insecticide applications.

Penetration Resistance- Developing a resistance to certain active ingredients used in insecticides is a normal response to chronic exposure within pest populations. The degree of resistance can also be determined by the genetic background of the insect, such as if its a first or second generation.

Typically, the second generation is the most problematic since hereditary genes are passed on from the first wave of infestation. These genes combined with the pests current exoskeleton can help reinforce protection by slowing the absorption of the insecticide. To avoid future generations gaining this trait, consider using insecticides mixed with an insect growth regulator like Tekko Pro IGR.

Metabolic Resistance- Besides behavioral resistance, the other most common mechanisms are seen in metabolic resistance. This form of resistance involves the insects ability to mutate their bodies to process toxins by using specific enzymes to detoxify the active ingredient being used.

Depending on the pest, some species could possess a higher, efficient levels of enzymes to break down toxic insecticide compounds. Once absorbed into a non-lethal compound, the pest will then evacuate the material to further evacuate the product from the pest.

Target-Site Resistance- This form of resistance occurs when the toxin binds to labeled areas in the pests, but the population has an altered binding site to avoid the insecticide's active ingredients.

Target sites will vary based on the insecticide, but is generally referred to the pests voltage-gated sodium channel (VGSC), nerve cells, respiratory system, muscles, or other areas. It is also more specific to a particular group of insecticides so if the insect comes across this products chemical class again it is less likely to suffer.

How to Avoid Insecticide Resistance

Homeowners can help avoid insecticide resistance through prevention with these key strategies:

Monitoring: Inspection is an essential activity that homeowners can implement when using an insecticide resistance method. Homeowners should observe if the insect population increases before spraying an insecticide. Once you have applied your selected pesticide then continue monitoring the treated area to see if insect population is still active and growing.

Rotate Modes of Action: A key strategy is rotating the mode of action, such as switching between a product that works on the pest's nervous system or its growth of development. You will also want to use the product within its labeled range. As with these other practices, another good method to use is an insect growth regulator (IGR) to disrupt future mating activities.

Make Applications in Appropriate Season: Timed applications are needed when pests are beginning to become active or prior to season of activity. Selecting insecticides with a broad-spectrum and long-lasting residual like Supreme IT will help control pests.

Mix and Apply Per the Product Label: Avoid the risk of resistance by correctly mixing selecting pesticides as stated on the label instructions. This further spreads to other areas as well as the pH of water used to dilute products may need to be adjusted per the labels specifications.

For aerial applications, swath widths should be marked and adjusted accordingly. Check sprayer nozzles for product blockage or wear, it should be suitable enough to handle mild spraying pressure. Calibrate spraying equipment such as backpack or handheld pump sprayer to appropriate calibration, which could include a fan spray or jet-stream setting.

Alternate Insecticide Classes: Homeowners should avoid the repeated use of the same insecticide within the same chemical class. Repeated use in the same year or the following can lead to resistance or cross-resistance. At the same time, mixing products from the same chemical class in the same spray tank can also contribute to pest resistance.

Key Takeaways

How Does Pest Resistance Occur?

• Pest resistance occurs when a portion of the population becomes adjusted in either their behavior, penetration, metabolic, or learns to avoid treated areas.

What is the Best Way To Prevent Insecticide Failure?

• Its important to avoid failure of insecticides and pest resistance by alternating between different products being used, making applications when the pest is first emerging or prior, and following the labels instructions for mixing and spraying.

Why Do Pesticide Applications Fail?

• Applications can fail due to a variety of factors like the pesticide not being applied at the right time, pest becoming resistant, using the wrong mechanical setting, or inappropriate insecticide.