[Cockroach Control] Practical Application for Biological Control

Biological control (the use of beneficial organisms — biorationals — to help manage pest organisms) has been practiced with mixed success and failure for nearly 200 years.

Unfortunately, biological control success stories are conditional because biorationals:

• Often require special application and environmental conditions for proper performance.
• Can reduce targeted pest populations to more tolerable levels, but not eliminate them.
• Generally require weeks or months to have a noticeable effect on target pest infestations.
• Often dwindle to ineffective numbers when their host and prey populations diminish.

BIORATIONAL SUCCESS. Despite the shortcomings of biological control, some biorationals have a favorable track record and, therefore, merit consideration for use in Integrated Pest Management (IPM) programs. These include:

• Beneficial strains of aerobic bacteria used to render wet floor drains uninhabitable by German cockroaches and the larvae of small flies
• Pathogenic bacteria and insectivorous fish for outdoor mosquito management
• Parasitoid wasps for indoor control of cockroaches

Fly and cockroach prevention. Currently, the most practical and affordable bioremediation of pests in commercial settings is the reduction of small fly breeding media in drain lines.

Several drain treatment products, formulated as gels and foamable liquids, contain active or dormant cultures of waste-digesting Bacillus bacteria. These products are intended for application to floor drains, sink drains and traps following end-of-day or start-of-day clean-up regimens. The bacteria break down the organic scum (biofilm) and food residues that accumulate beneath or at the rims of drain cut-outs in floor tile and in drain lines and traps.

However, such applications are effective only when bacteria have ample time to digest the organic residues before being rinsed away by staff members. Frequent (daily or every other day) applications of bacterial product are required initially in problematic areas to remove thick accumulations of food waste and biofilm, especially if physical cleaning of drains is not implemented. Once most of the residue has been cleared, then weekly or biweekly treatments should be sufficient to prevent small fly larvae from breeding in drains.

Mosquito management. For decades certain strains of bacteria, especially Bacillus thuriengensis israelensis (Bti), have been used to help manage mosquito populations by infecting and intoxicating the larvae (wigglers) in still, standing water, including ponds, small lakes, storm drain basins, ditches and tree holes.

This bacterial strain is available in a variety of formulations, including dunks and granules, and is a cost-effective, low-impact way to impact mosquito breeding sites where circumstances or budget do not allow the use of an insect growth regulator or other chemical insecticides.

The mosquitofish is a small, prolific species with a big appetite for mosquito and chironomid midge larvae. Once introduced, they perform best in standing water that isn’t too shallow, lakes, ponds, canals, and abandoned swimming pools.

Thanks to the Louisiana State University AgCenter, the strategic release of mosquitofish is one of the weapons in the IPM arsenal of the New Orleans Mosquito and Termite Control Board, as field agents struggle to control mosquitoes in post-Katrina, hurricane-stricken New Orleans.

Cockroach maintenance. A tiny eulophid wasp has demonstrated its usefulness as a parasitoid of the oothecae (egg sac) of cockroaches, especially in areas where controlling indoor populations of cockroaches is difficult due to situational constraints.

Eulophid wasps are mass-reared and available for use in cockroach-breeding areas of buildings, including boiler rooms, steam tunnels, pipe chases, open floor drain systems (not having water-filled traps) and inaccessible, structural voids.

GROWING SUCCESS. Whether we’re conscious of it or not, thankfully, biological control (pest predation, parasitism and pathogen-related mortality) is a tool that is being successfully used to manage pests.

 
The author is technical director and staff entomologist, ProGuard Commercial Pest Solutions, Columbus, Ohio. He can be reached at gwegner@giemedia.com.