The most common structural fumigants are phosphine, methyl bromide and sulfuryl fluoride. Bakeries that use phosphine find it corrodes electrical conduits, especially at high humidities, notes Raj Hulasare, Ph.D., senior scientist and project manager, TEMP-AIR Inc., Burnsville, Minn. Methyl bromide has been a standard structural fumigant, Hulasare adds. However, the Montreal Protocol, a global treaty, has mandated the phasing out of methyl bromide because of its ozone depleting effects.

Three factors are associated with using chemicals, according to Hulasare. One is consumer preference for pesticide-free products. Secondly, global protocols and other regulatory issues make it difficult for bakeries to use chemicals. Thirdly, insects build resistance to chemicals, requiring the use of higher doses to get the same level of kill.

In addition, insects have four life stages: eggs, larvae, pupae and adult. The degree of insect kill is influenced by the species, life stage of the insect, and type and effectiveness of control tactic used, Hulasare notes. “Generally with fumigants, eggs and pupae are difficult to kill, compared to larvae and adults,” he adds. How quickly insects rebound after an intervention is based on the degree of insect suppression obtained following an intervention.

Some of the newer “green” products available for use as insecticides contain plant essential oils, Copps notes. In addition, some of the older materials have been reformulated to allow a more environmentally friendly label designation and a lower use rate.

Temperature and humidity can be effective pest control tools, particularly when product is storedin a cool, dry place. Thermal remediation, or heat treatment, is a chemical-free method first used in the early 1900s for structural pest control that is gaining quite a bit of momentum today.

Thermal remediation

During heat treatment, temperatures within a space that's being treated are raised to 120°F (50°C) to 140°F (60°C) and held for 24 hr., although the hold may be reduced to 18 hr. or 20 hr. depending on the structure. Heat treatment is very effective because it basically kills all the insects' life stages from eggs to adults, Hulasare notes. In addition, unlike chemical fumigants, part of the facility, such as the silo room or receiving area, can be selectively heat treated, while the rest of the facility continues to operate normally.

Before the heat treatment is done, Hulasare and his co-workers extensively interact with the quality control and production staff so no damage occurs to any equipment or to the facility itself. For example, pressurized containers, such as fire extinguishers, aerosol cans, etc., must be removed from the area.

Different methods of heat treatment exist. TEMP-AIR uses a patented process, where heaters are placed at exit points, such as loading docks or doors, and placed partially outside. Outside air is pushed through the heaters and then distributed throughout the treatment area via high-temperature ducting. Although windows and doors are closed, they do not have to be sealed, as they would for fumigation. The process positively pressurizes the area that's being treated. “The whole process is dependent on how many air changes we can achieve,” Hulasare says. “We aim for about four to six air changes, which means if we're heating a room, we like to change the entire volume of air at least four to six times per hr.”

Among the many benefits of heat treatment is the ability to enter the facility while the treatment is in process. When he enters the areas undergoing treatment, Hulasare follows what's called a “buddy system,” because of the extreme temperatures. What he initially observes is all the insects going to the colder areas to escape the heat. Eventually, the heat penetrates those areas as well.

Wireless real-time temperature sensors are used to ensure uniform temperature profile and thorough air distribution throughout the treatment area. These sensors can be monitored from an office laptop. “The key is to identify hot and cold areas when you're ramping up the temperature, so that corrective action can be taken,” Hulasare says.

Heat treatment is very effective as long as the bakery has good sanitation practices, monitors its incoming raw materials and follows an IPM approach. “Last month, when we did a heat treatment, it was a great success. You could see hundreds or thousands of dead insects all over the facility. The next day, they received a shipment that was infested, so then everything went back to zero,” Hulasare says.

Still, heat is not a “cure-all” solution and may have to be used in conjunction with other physical and chemical control methods for effective IPM.

A comprehensive approach

Bakers cannot leave the entire process of pest management up to their pest control supplier. “If bakers aren't cooperative, the process is going to fail,” Sargent says. Proper communication, sanitation, monitoring and accurate reporting of problems are keys to IPM.

“An effective and environmentally friendly pest management program requires a partnership and an investment of time for the inspection process, treatment solutions, education of the customer and follow-up that are needed,” Copps says. Regardless of the ultimate solution used when a problem occurs, one of the most important aspects to pest management is the approach taken. A good sanitation program and thorough monitoring go a long way toward curbing the need for application of any type of pesticide use.

“IPM really is a green approach, if you look at the principles of it,” Sargent says. Standards beyond that aren't really needed. By definition, a bakery should be doing everything it can to keep the pests out and minimize pesticide use. After all, the most cost effective and environmentally friendly solution is to keep pests outside of the bakery environment in the first place, Sargent adds.