Formulations, Actives and Modes of Action

As a technical person, I get asked a lot about product selection and what to use for what pest. I wish it was that easy.

This often leads me down a line of questions about what has been used previously, what type of surface they are treating and what kind of account they are dealing with for the pest. It may also involve questions about non-targets, children, pets, sensitive persons, etc.

Hopefully, these next few paragraphs will help you to understand why us cranky technical people are always asking so many questions — because they matter.

FORMULATION. The formulation of a product is how the active and inert ingredients are blended to make the product perform in a certain way.

This may involve making it mix well with water, not mix with water at all, stick to a plant surface, not foam, get extra foamy or even stay suspended in the air for a long period of time. You may know them by terms like suspension concentrate, granules or any of the other extensive lists of abbreviations we see on product labels.

These formulations have times and places when they may be better suited to application. For example, porous surfaces tend to absorb liquids, so if you needed to make an application to something like masonry block or brick, you would want to use a product that is formulated to leave the residual material behind on the surface of the block — say, a wettable powder or a microencapsulated product. This leaves the active available for a pest to encounter instead of soaking in with a product like an emulsifiable or suspension concentrate.

Each formulation has specific properties that makes it good or bad for a variety of surfaces.

ACTIVES. The active ingredient in the product is what takes action on the pest. It may kill, repel or sterilize, but it’s performing the action.

Actives are as important as formulation, but different in every way. All the fantastic products we have today have one or more active ingredients. Sometimes manufacturers put the same active in multiple products. Often, these will carry a similar name on the product label. Typically, the trade name of a product can alert you to the similarities, but we also run into several manufacturers having the same or similar actives that don’t carry the same product name. This is where it can get confusing.

Even more confusing is that actives are grouped into classes where they act on pests in the same way. Consider the pyrethroid insecticides. While there might be some actives that work faster or slightly better on a specific insect, bifenthrin, deltamethrin, cyfluthrin and cyhalothrin all act on the same place of the insect nervous system.

Therefore, if your target pest is resistant to a bifenthrin product, you are likely to see some level of resistance to other pyrethroid-containing products.

MODES OF ACTION. The way you combat resistance is by changing the mode of action on the pest — in other words, where in the pest the active works.

Groups of active ingredients are given numbers (and letters sometimes) from a group called the Insecticide Resistance Action Committee (IRAC). There are currently 33 class numbers, and these numbers represent different modes of action on pests.

You may have seen these numbers/letters on some product labels. They are in a little black and white box and may be something like Group 3A or Group 13. You can use these numbers to rotate products and combat resistance. If you’ve been using a 3A, swap to a 4A or 13. All of these will act on the pest differently and increase your success.

The IRAC has an app in the event you can’t find a group number on your label. You just start typing the active, and blammo, you get a number. It can be very helpful. Remember, just rotating product names may not be rotating the mode of action.

If you need more help with all of this, or if you are having trouble figuring out why your product is under-performing, reach out to your distributor or manufacturer. They can assist you with treating complex surfaces or the unusual properties of a ZC (mixed) formulation.

Ultimately, the professional products on the market work when they are applied correctly and to the right surfaces. Product failure is a result of putting the product in the wrong place so that the pest doesn’t come in contact with it. Fix that, and you fix your pest problem.

The author is senior technical services manager at Rollins in Atlanta.