The Silver Bullet

The pest management industry frequently expresses concern about silver bullets that could put us out of business. Probably the first expression of concern was regarding the proliferation of synthetic pesticides following World War II. These new products were inexpensive, easily applied and highly effective against a broad spectrum of pests...that is, until resistance and the EPA reregistration process came along; then many were lost.

Then there was chlordane and other chlorinated hydrocarbons that seemingly would last forever in the soil and thus, provide inexpensive, long-lasting barriers against the onslaught of termites. But persistence in the soil and environmental concerns became an issue and all were lost.

Both the loss of these products and EPA’s policies have resulted in a reshaping of the pest management industry...in most cases, for the better. The loss of products due to resistance and the reregistration process have led to the development of new active ingredients that are far more effective at lower concentrations and rates of application than were their predecessors.

BAITS VS. SPRAYS AND AEROSOLS. We have turned the corner into the next century. Now baits are the rage. We have new active ingredients and bait formulations for cockroaches, ants, termites and a host of other pests.

Perhaps we have found the silver bullet for cockroaches. Will we eradicate cockroaches from the face of the earth using baits? There is little probability of this occurrence. However, it is quite possible to forecast that we will see a significant reduction in the demand for our services, particularly as it relates to cockroach infestations. The many reasons for this are as follows:

• Although many factors affect the longevity of baits, typically, they remain available to cockroaches for long periods of time. In contrast, many residual insecticides and aerosol sprays are short-lived.

• Baits are not absorbed by the surface on which they are applied, and, thus, remain available unless the bait is totally consumed. The effectiveness of sprays is greatly affected by the surface on which they are applied, e.g., because wood and plaster are porous and readily absorb liquid formulations, they are not available to the cockroach. Liquids tend not to adhere to non-porous surfaces, so the product could run off the surface or spread out in a thin layer. In this case, the insecticide is not available in heavy enough concentrations.

• There is very little, if any, resistance problem associated with bait active ingredients such as boric acid, hydramethylnon, sulfluramid, imidacloprid and fipronil. At least two reasons for this include: 1) baits are ingested and escape some of the detoxification mechanisms encountered by liquid insecticides, e.g., absorption through the cuticle; and, 2) most baits contain novel active ingredients which have not been widely used and do not seem to be significantly impacted by any cross-resistance.

• Baits can be applied to cockroach harborage areas with little risk of contaminating food, pots and pans, dishes and food preparation surfaces. In addition, occupants do not have to leave the area during application. On the other hand, liquids and aerosols cannot be applied in areas where there is risk of environmental contamination and/or human exposure. Thus, the use of sprays can lead to significantly more untreated cockroach harborages and the subsequent development of heavily infested foci.

• Some bait products have the added advantage of secondary killing effects due to coprophagy (feeding on feces) and cannibalism of cockroaches which have ingested the bait. These behaviors are of little consequence for cockroaches that have been exposed to residual and aerosol insecticides. The metabolism and detoxification of absorbed insecticides is significantly different from ingested products. This alone could be the major reason that the baits have this secondary killing effect.

• Baits, as the name implies, are designed to attract cockroaches. When most gel baits are applied in close proximity to cockroaches, the cockroaches explore and then feed on them. While this is a short-range effect, the same behavior does not occur with aerosols and sprays. In fact, in some cases, these products have the opposite effect and, thus, repel cockroaches. Aerosols rely on direct contact with the cockroach in order to kill it. Residuals are applied in the hope that the cockroach will initially contact enough insecticide to effect a kill or that it will contact the product enough times to pick-up a lethal dose.

• Baits have many other advantages, e.g., they have no detectable odor, no volatility, minimal applicator health risks and are applied at very low concentrations — in some cases 50 times less than their counterpart sprays.

THE OTHER SIDE. However, baits do have several shortcomings:

• Customers and technicians do not get the "thrill of the kill" that typically occurs with sprays and aerosols. Baits are slow acting, so population reduction takes at least three to five days before it is noticed. The body count with baits is low because most cockroaches die within their harborages.

• Customers are slow to accept baits as an alternative to sprays and aerosols. They have been conditioned by the industry throughout the past 50 years to expect a spray and fog treatment. However, with the widespread use of baits, this paradigm shift is slowly taking place.

• If baits are not applied directly into cockroach harborages, and if they are misapplied, they are very visible to customers. Once dry, baits are difficult to remove, and, as with sprays, baits can stain certain surfaces.

This is not a slam against sprays and aerosols; to the contrary, they still have a place in our industry. But cockroach baits probably are the closest thing we will have to a silver bullet for a long time. Products are changing and, in my opinion, for the better.