[Cockroach Control Issue] Maximizing Cockroach Control with Baits

German cockroaches are one of the leading indoor pests. Their preference for hard-to-access harborage sites and an innate ability to multiply rapidly keeps the German cockroach in the forefront of homeowner and pest management professional minds alike. Tendencies of the German cockroach include a disdain for light but preference for easy access to water; they exhibit a collective nature rather than solitary. An adult cockroach can live up to 10 months and a single female can produce more than 350 offspring during her lifespan.

As the most widely dispersed species globally, the German cockroach could arguably receive the most exposure to pesticide treatments. This means pest management professionals should watch for empirical signs of cockroach adaptation to treatments and stay abreast of product research. 

CHOOSING A CHEMISTRY. Several new chemistries on the market today are effective in controlling both normal and bait-resistant cockroaches. This is important since pockets of cockroaches show varying levels of acceptance to old bait formulations or varying susceptibility to the toxicant. Pest management professionals should be mindful that products are labeled or designed for certain species so it is important to understand and identify the species being treated.

Another consideration for pest management professionals should be the level of secondary control a product can provide. Baits with the active ingredients of hydramethylnon, fipronil, indoxacarb and acetamiprid can achieve direct kill as well as induce significant secondary kill to cockroaches not exposed directly to the bait. These ingredients contribute to the overall efficacy of gel baits against field cockroach populations. Recent studies have shown that cockroaches can ingest the bait and, through normal cockroach behaviors, share it with others.

Typically, the compound is broken down by the digestive processes in the insect such that the secondary level of control is significantly less than direct ingestion; however, the secondary kill effect on reducing the population provides an added effect to direct ingestion and proved to be a benefit for the active ingredients studied.

MAXIMIZING BAIT EFFECTIVENESS. When applying a bait product, pest management professionals should keep in mind that its effectiveness will ultimately depend on the applicator. Thus, the following three points are most important to maximize the effectiveness of the bait:

1. Thoroughness. Every possible harborage site should be examined and treated. It is possible to achieve 100 percent control after a single application of a highly effective bait product.

2. Sanitation. Insist that the customer remove garbage, alternative food resources and clutter. Customer cooperation will not only reduce the amount of bait used, but also increase the overall effectiveness of the bait.

3. Follow up. You never know if you have missed any sites or applied enough bait during the first visit. Monitoring is key. One or two follow up services will often be needed.

Changlu Wang and Gary Bennett are with the Center for Urban and Industrial Pest Management, Department of Entomology, Purdue University, West Lafayette, Ind. Clay Scherer is with Global Product Development, DuPont Professional Products, Wilmington, Del. Contact the authors at cwang@giemedia.com, gbennett@giemedia.com and cscherer@giemedia.com.

Cockroach Baiting Dos and Don'ts

Do:
Use sticky traps to guide bait placement and evaluate treatment efficacy.
Ask questions to residents or staff. Their observations and comments can provide very valuable information.
Consider the structure type. Inspect neighboring rooms of the infested area or neighboring apartment to an infested apartment.
Include non-chemical tools (trapping, vacuuming) to supplement the treatment or provide immediate impact. These elements are key components of Integrated Pest Management. With this in mind, cockroach elimination should be achieved after two to three services, even in challenging situations. This IPM strategy is not only cost effective in the long term, but also reduces the speed of cockroach resistance development.
Put in place a proactive monitoring plan of all structures in the same community. Cockroaches can spread by human activity and natural dispersal between neighboring rooms. A community-wide IPM program will work most efficiently and effectively to maintain a cockroach- free community.
Don’t:
Leave the account without discussing your management plan with your customer. The communication will not only present the customer a professional image of you and your company, but also help gain the customer’s cooperation.
Treat the reported infestation area only. The neighboring areas need to be inspected and treated accordingly.
Apply excessive amount of bait. Large amount of residuals are indications of poor placements, over-application or bait resistance.
Use the same bait products for extended periods in the same accounts. While this makes the technician’s work simpler and the material cost lower, it encourages resistance development in cockroaches. To maximize a product’s usable life and reduce the long-term cost, pest management professionals should avoid such practices. If cockroaches can not be eliminated with bait in a short period of time, alternative formulations must be considered. Also, careful application of alternative formulations such as dusts can provide high levels of control.