[Research & Development] The Power of Crystal Technology

The professional pest management market has come to rely on modern pyrethroids for their quick knockdown, large number of pests controlled and long-lasting residual properties. The most common formulations include suspension concentrates (SC), emulsion concentrates (EC) and capsule suspensions (CS).

Choosing the best formulation is the key to a successful job. Temperature, whether a surface is porous and the surrounding moisture all factor into the efficacy of a formulation.

Emulsion concentrate formulations rely on oil solvents to deliver active ingredient to surfaces. ECs mix very well, but on porous surfaces, the solvent may penetrate too deeply, making the active ingredient unavailable on the surface.

Capsule suspension formulations are formed by enclosing an active ingredient in a polymer sphere and suspending the spheres in a water and/or oil solvent. The polymer membrane may prevent the active ingredient from being available when an insect comes into contact with it, such as in wet areas, where the AI doesn’t release well.

Suspension concentrate formulations are formed by suspending fine particles in water and/or oil solvents, which can be applied effectively to both porous and non-porous surfaces. For any suspension formulation, particle size plays a critical role when applied to different substrates, as smaller particles traditionally fall into the cracks of porous surfaces. The nature of SC formulations, however, means the particles will not be absorbed into surfaces, but will remain immediately available for insects to contact.

For many pest management professionals, the SC formulation is just another all-purpose, water-based liquid formulation. However, these water-based formulations are valuable to professionals for many reasons. They are simple to use, less messy to handle, require less agitation to mix, carry less concern of phytotoxicity, low odor and are less visible on surfaces.

After many years of research on product chemistry and new manufacturing processes, Tempo SC Ultra has been improved to increase residual control and still provide superior knockdown, according to Bayer ES research scientists. The secret to this success is a specially designed mixture of particle sizes in a water-based formulation.

ALWAYS ACTIVE. Beta-cyfluthrin, the active ingredient in Tempo SC Ultra, is actually a crystal that occurs when cyfluthrin is refined into its most active isomers. Cyfluthrin was first introduced to the pest management industry in the late 1980s as Tempo 2 and then reintroduced as Tempo 20W, a wettable powder formulation.

"Throughout the 1990s, Bayer formulation chemists worked to produce a replacement liquid formulation for Tempo 2. At the same time, Bayer scientists had successfully isolated the most active isomers of cyfluthrin to make beta-cyfluthrin. Both efforts led to the development of the liquid formulation of beta-cyfluthrin, now known as Tempo SC Ultra," said Dr. Byron Reid, product development manager for Bayer Environmental Science.

During the refinement process, a highly active crystal is formed. Beta-cyfluthrin is then put through a special milling process, which produces a specific range of minute particle sizes designed to control all types of insects. The solution came about by suspending beta-cyfluthrin crystals in water. When used, the spray dries and the crystals remain on porous and non-porous surfaces to be picked up easily by insects (see Figure 1 on page 55). Each crystal is pure active beta-cyfluthrin that acts as a free agent against insects at all times.

Because it does not require breakdown or transfer through a polymer microcap membrane, beta-cyfluthrin crystals begin to work immediately, Bayer reports. The crystals adhere to insect tarsi and are either absorbed through cuticles or ingested by grooming body parts (see Figure 2 on page 55).

"Sodium ion channels, found in nerve cell membranes, stimulate the movement of electrical impulses within a nerve cell. Beta-cyfluthrin holds these sodium ion channels open, causing a continuous electrical signal to be sent to the nerve," Reid said.

OPTIMIZED SIZE & COVERAGE. In order to provide immediate efficacy, crystal size and coverage play major roles in the formulation. Typically, smaller crystals are picked up by smaller insects, while larger crystals are most readily picked up by larger insects. Tempo Ultra has been specifically designed to provide an optimum mixture of crystal sizes to control the 100+ pests listed on the label. "Smaller particles offer faster control, while larger particles offer longer residual. PMPs get the best of both worlds with crystal technology," according to Bayer ES.

"It’s easier for the smaller particles to fall into cracks, where smaller insects with smaller tarsis travel. So smaller insects, traveling in smaller spaces, are more likely to pick up the smaller particles," says Jing Zhai, technical service and field development representative for Bayer Environmental Science. "On the other hand, the large insects that are too big to fit in tiny cracks and crevices are more likely to pick up the large particles that remain on top of surfaces treated with beta-cyfluthrin."

To create this optimum range of particles, Tempo SC Ultra is passed through a special milling process, which produces particles that range in size from 0.5 to 17 microns. Studies have shown that variation in particle size provides superior efficacy, Bayer ES says.

CRYSTAL COVERAGE. Optimized coverage of crystals on surfaces is also critical in terms of speed of control. More crystals on a surface area means faster pick up by insects.

A study was conducted using 0.05 percent Tempo SC Ultra applied evenly to a glass surface. The number of micro-crystals on the surface was counted under a microscope (see Figure 3 above left). In each square inch, an average of 116,000 crystals covered the surface, ranging in size from 0.5 to 17 microns.

Because of its special crystal size range and coverage, beta-cyfluthrin also provides better residual effectiveness. Beta-cyfluthrin crystals are stable and can last for months when applied to a surface and left undisturbed, Bayer reports.

The authors are northeast field sales representative and technical service and field development representative, respectively, for Bayer ES. They can be reached at smullen@giemedia.com and jzhai@giemedia.com.

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Tips for Treating with Beta-Cyfluthrin
To maximize your results with “crystal power,” pest management professionals should pay special attention to targeted treatment zones and the amount of chemical that is used. Other tips include:
• Treat the building foundation, walls, around doors, windows and soffit areas.
• Also focus on siding and cracks along a foundation. In areas that don’t receive sunlight, you may benefit from an increased residual effect.
• Treat the zone between mulch and a structure. Because mulch and pine straw make control of perimeter pests more difficult, rake them back before application wherever possible.
• Remember to treat based on square footage, rather than by volume of chemical. A little active ingredient goes a long way.