In Germany, methyl bromide is used primarily to fumigate structures like flour mills and food factories to control pests in stored products. Some of the 90 tons used annually is to control beetles that destroy altars and other precious wooden artifacts in churches and museums.

Christoph Reichmuth says that Germany has greatly reduced its use of methyl bromide, but is still investigating chemical, nonchemical, and integrated pest management strategies as possible replacements. He is director of the Institute for Stored Product Protection, which is part of the Federal Biological Research Center for Agriculture and Forestry in Berlin and Brunswick.

"However, we are urgently searching for ways to modify and optimize our existing use of methyl bromide," he says. "There is a chance that we can further reduce our dosage and still kill pests in stored goods."

According to Reichmuth, the seals in structures being fumigated are routinely tested to ensure quality prior to methyl bromide treatment, often cutting down on the amount of the chemical needed. Even in a fairly gas-tight building, Reichmuth says, about 50 percent of the methyl bromide used in a treatment can be lost in 2 days.

"In a large-scale experiment, we're using charcoal to absorb methyl bromide instead of venting the gas into the air at the end of fumigation," he says "But, we need to consider the large amounts of charcoal that would be needed to significantly decrease gas emissions. To be effective, we would need to cut emissions by 50 percent."

In addition to chemicals, since the early 1920's the Germans have been studying the use of a parasitic wasp, Trichogramma evanescens, to control moths that cause problems in flour mills. Two of Reichmuth's colleagues at the Institute, Sabine Prozell and Matthias Schoeller, are using the wasp against the warehouse moth (Ephestia elutella), and the Indian meal moth (Plodia interpunctella). In Germany, these insects are severe pests in stored grain and the food processing industry.

"Preliminary results are promising that these wasps will find their place in controlling pests of stored products," Reichmuth reports. "We hope they may replace some chemical control agents."

He says they have shown that controlled temperatures, heat and cold, are a possible replacement for methyl bromide in smaller flour mills. However, he says they have encountered problems with obtaining even distribution of heated and slightly humidified air. Heat treatments must be repeated more often than methyl bromide treatments throughout the year. Other than with methyl bromide fumigation, complete control of all stages of insects in various crevices in structures and inside machinery is hard to achieve. They've observed insects trying to escape heated machinery during a heat treatment.

Regarding cold, both moderate and deep cold treatments are used in Germany, in the form of liquid nitrogen or air, carbon dioxide, or electrical cooling.

Other chemicals that the Germans are trying as substitutes for methyl bromide include carbonyl sulfide and sulfuryl fluoride, as well as combinations of phosphine and carbon dioxide and carbon dioxide under high pressure.

"We've found that elevated temperatures along with phosphine or mixtures of carbon dioxide or nitrogen with low amounts of oxygen fulfill the requirement of quick disinfestation," Reichmuth says. Like methyl bromide these methods leave little or no residue, but they are more expensive. The original research, he says, was done by ARS scientists.

Although the Germans are investigating natural insecticides as potential alternatives to methyl bromide, there is a problem in Germany as there is in the United States, of registering these extracts since they are mixtures of several chemicals.

"Our postharvest pest control market is rather limited and does not guarantee a quick amortization of the registration cost," Reichmuth says. "Therefore, the registration process is slow."

One of the research areas of the future for German scientists is in early detection and monitoring of insects. Since nearly all pheromones of important pests of stored products are detectable and can be synthesized, these are important aspects of integrated pest management. German scientists plan to combine pheromone traps with insecticides or biocides like viruses, Bacillus thuringiensis, or entomophagous fungi.

"The way of the future may mean that we use biotechnology to produce new types of insecticides or insect-resistant products," says Reichmuth. "Our search for a cheap, versatile replacement for methyl bromide is far from over."