Pest Control in Tobacco Warehousing

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The dreaded cigarette beetle and similarly destructive tobacco moth can wreak havoc on storaged tobacco.Tobacco Asia takes an in-depth look at the two currently most commonly used pest control methods.

By Thomas Schmid

Natural evolution has bestowed the tobacco plant with an ingenious defense to keep most pests at bay: its nicotine content. There are no known mammals, reptiles, amphibians, or birds that feed on its toxic leaves, stalks, or seeds. The same goes for practically all insect species.

But as always, there have to be exceptions. In tobacco’s case, these primarily are the dreaded tobacco beetle (Lasioderma serricorne, often also called cigarette beetle, cigar beetle, or warehouse beetle) and its similarly destructive cousin, the tobacco moth (Ephestia elutella, a.k.a. cocoa moth or warehouse moth). Both insect species - or to be more precise, their larvae – just love to gorge themselves on tobacco. While tobacco can be infested with these two nasty critters at any stage, their presence can be especially troublesome during sometimes quite prolonged storage periods tobacco crates, bales, and pressed lamina or rag commonly undergo. Both species thrive in warm and humid warehouse environments, their larval stages wreaking havoc as they voraciously feast on the precious commodity, additionally contaminating it with their excretions. And while rodents and other small animals do not feed on tobacco, their presence in storage facilities still is unwanted and potentially unhygienic as their bodily waste or carcasses may find their way into the product.

But there exist effective treatment options which reliably exterminate any pest infestations during warehousing or pre-shipping: Fumigation with phosphine gas (PH3) has been used for decades, is globally approved, and necessary to meet phytosanitary certification requirements. Secondly, there is the still relatively new – but increasingly popular – process of subjecting a commodity like tobacco to a low oxygen environment, a method called “controlled atmosphere treatment”.

Detia Degesch: providing the ‘golden standard”

“Detia Degesch product solutions are considered the ‘golden standard’ in fumigation treatment in any part of the world where tobacco is grown, processed, stored or transported, both for export and import,” said Baldur Grunt, head of international sales and v.p. at Detia Degesch GmbH in Germany, a leading manufacturer of aluminum and magnesium phosphide insecticides and CORESTA member

Warehouse operators can easily determine whether their storage facilities have become infested with the cigarette beetle or tobacco moth by monitoring so-called “insect pheromone traps,” which can indicate whether insect levels have reached an “action threshold” that would necessitate fumigation (or an alternative treatment), according to Herb C. Yeaman, president of Degesch America Inc., headquartered in Weyers Cave, Virginia. “The cigarette beetle and tobacco moth are very common and most infestations occur during storage and transport,” he said. “Having proper and standardized integrated pest management procedures in place will help reduce the risk of infestation and reinfestation, as particularly (adult) cigarette beetles can fly up to 3 kilometers looking for a mate to reproduce.”

Using the CORESTA fumigation guidelines

The primary chemical method used today for infestation control is through thorough fumigation with an agent releasing phosphine (PH3), a gas resulting from a chemical reaction of phosphide compounds with air humidity.

“Our Magtoxin Degesch plate is the first choice when fumigating tobacco,” said Yeaman. “It is preferable to pellet fumigants, as it does not contain ammonium carbamate, which may affect the smell, taste, and color of tobacco. We are using the time, dosage, and temperature standards established by CORESTA.”

Adhering to the dosages, concentrations, and exposure times recommended in the relevant CORESTA Guide No. 2 will ensure that all four life cycles of an insect (that is, egg, larvae, pupae, and adult) are reliably exterminated. Almost needless to say that rodents also perish during treatment. However, if fumigators do not obey these protocols to the point, there is a risk of failed phosphine treatment, Yeaman cautioned.

Careful preparations and adequate exposure

Prior to fumigation, it is important to prepare a fumigation management plan (FMP), i.e. detailed steps how to seal and close off the warehouse, apply the fumigant, monitor fumigant concentration, accomplish post-treatment aeration, and, lastly clearing the facility for re-entering by humans.

“Once the FMP is prepared, [all] openings to the warehouse such as doors, louvers, ventilators, etc. are temporarily sealed using tape, adhesive, and plastic sheeting,” elaborated Yeaman. “Warning placards are attached and the fumigant is applied, the commodity’s exposure time typically being between 96-144 hours. During exposure, fumigant concentrations are periodically monitored to ensure an adequate level is maintained.” At the end of the exposure period, the storage is aerated naturally by removing the temporary seals. Once the process is fully completed the warehouse can be accessed by humans again.

Peterson Pest Control: widely represented

“We maintain representations in all relevant Asia Pacific markets [for tobacco],” remarked Nico Vroom, project director of Peterson Pest Control, headquartered in Rotterman, which is another leading global provider of tobacco warehouse fumigation solutions. Like Yeaman, he insists that infestation does not necessarily happen in the warehouse itself, but just as well can occur on the tobacco plantation or at the curing facility. In other words: In such cases the infestation is actually introduced into the warehouse, where beetles and moths then can continue their destructive work.

Particularly for cigarette beetle extermination, Vroom recommended a choice of three methods:  the already discussed PH3 (phosphine gas) fumigation, but also freezing of stored product (both beetles and moths at any life cycle stage are extremely susceptible to low temperatures), and controlled atmosphere treatment. Despite the phosphine agent’s ability to permeate packaging materials, including cellophane wrapping, and to penetrate deeply into even highly compressed tobacco, treatment will not leave behind chemical residues if the procedure is executed correctly and in line with established protocols.

Nevertheless, there is the question of whether or not pests such as the cigarette beetle have developed “resistance” against existing fumigation methods (which could soon render them worthless) or whether it is merely a pronounced phosphine “tolerance”. If the latter, it could necessitate higher ppm concentrations to achieve extermination. However, Detia Degesch’s Grunt remarked that any potential increase in concentrations “must be supported by studies and research.

A good alternative: controlled atmosphere treatment

Whatever the truth may be, controlled atmosphere (CA) solutions have steadily gained in popularity in recent years. The principle behind this treatment method is rather simple: Every living organism (bar some strains of anaerobic microbes) needs a certain level of oxygen to function, to metabolize – and to survive. If that oxygen is denied, that organism is going to suffocate. By volume, natural air is primarily composed of nitrogen (78.09%), and oxygen (20.95%), as well as a host of other gases in smaller and trace amounts. If the oxygen available in a hermetically sealed space is artificially decreased to a very low level, the organism exposed to it will inevitably die as it can no longer breathe.

EcO2 Projects B.V., a de-facto sister company of Peterson Pest Control, is offering this simple yet apparently highly effective treatment option and is also very active in Asia. EcO2 established an office and treatment facility in Vietnam in because its controlled atmosphere technique is well suited for the treatment of cashews, one of the main export products of Vietnam.

“Our CA solutions are widely used by renowned tobacco companies in various Asian countries,” said Wouter van Ravenhorst, project manager of EcO2 adding that the company had recently completed a project in the Philippines. Although EcO2 currently considers Vietnam, Malaysia, Japan, and the Philippines as its Asian key markets, the company plans to “also focus more on India, Thailand, Indonesia, and Cambodia in the near future.”

Make that chamber tight!

During treatment of infested product in a hermetically sealed chamber, the nitrogen content of the air is increased to 99% or more, leaving less than 1% of oxygen. “This, combined with an increase in temperature, will exterminate any pests at any life cycle stage, from egg up until adult insect,” explained van Ravenhorst, adding that “the tobacco is being treated according to the CORESTA guideline No. 12,” which stipulates that the temperature during treatment should be 28º Celsius or higher. Besides providing CA treatment at storage facilities, the company also offers container treatment at load port.

“CA treatment of containers at load port can become necessary when the cargo has not been treated [at the warehouse] or if re-infestation has occurred after loading the container,” said van Ravenhorst. EcO2 currently provides container treatment services for tobacco at the load port in Beira, Mozambique.

B-Cat: focus on southeast Asia

Likewise dedicated to providing controlled atmosphere solutions, B-Cat B.V was founded in 2005 also in the Netherlands. According to its director, René Luyten, B-Cat established its own branch office in India in 2008, and considers Indonesia a key market as far as pest extermination is concerned: B-Cat has constructed two big projects there, one for Sampoerna (owned by Philip Morris International) and the other one for STTC in Sumatra.

“Another of our key clients is Japan Tobacco International, for whom we have installed CA projects in Malaysia and Taiwan,” said Luyten. “And we’ve also set up a facility for Philip Morris International in South Korea.

“Our credo is simple: no oxygen, no life,” said Luyten. “Like humans, insects can’t live without oxygen. High ambient temperatures help to accelerate treatment time. So contrary to freezing, CA treatment is an ideal technology for hot climates. Our ZerOx system is fully automated and therefore very user-friendly, meaning that all our projects are turn-key installed and our customer receives a brief training for easy self-operation.”

Luyten claimed that CA treatment, in general, was “a reliable, clean and safe technology, approved after years of thorough research done by CORESTA.” While he added that a CA treatment cycle could be completed faster than a fumigation cycle using phosphine gas, his observation is debatable. As Degesch America’s Yeaman noted, phosphine fumigation of tobacco in accordance with the CORESTA protocol lasts from 96 hours (4 days) to 144 hours (6 days) depending on the temperature – which is by and large identical to what CORESTA recommends for effective CA treatment as far as actual exposure time is concerned.

Phosphine "Resistance" or "Tolerance"

Throughout our interviews with the various contributors to this article, TobaccoAsia was confronted with a wave of opinions whether Lasioderma serricorne, i.e.the cigarette beetle, has in the meantime developed “resistance” to phosphinetreatment or merely a more or less pronounced level of “high tolerance” among an increasing number of beetle strains.

A proponent of the latter was DegeschAmerica’s Herb Yeaman, while Peterson Pest Control, its sister company EcO2and B-Cat all insisted that the cigarette beetle had become either “resistant”,“largely resistant” or “fully resistant” to phosphine agents.

The opposing points of view prompted Tobacco Asia to conduct some online research which is available here.

Not all is rosy

Nevertheless, while the CA method of pest control may impart some benefits over chemical fumigation, there is at least one important downside: For it to work effectively, the technology has to be applied inside a gas tight chamber. This immediately rules out the possibility of treating an entire warehouse at once; in one go, so to speak. It is practically impossible to hermetically seal a more often than not huge storage facility. The solution to the problem is installing dedicated treatment chambers either inside the warehouse or, alternatively, as a separate facility adjacent to it. That means a comparatively high initial investment, not to mention that sufficient indoors or outdoors space is needed for the chambers.

“After identifying the ideal location, we design the treatment rooms to fulfill the client’s logistic needs,” said Luyten. “Once that is worked out, a technical team will start assembling the gastight panel for the CA chambers. The technical equipment… will then be installed on site by a second team. Once that is completed, a supervisor inspects everything and will conduct a full system training for the [storage facility’s] employees.” Ideally, a CA chamber ensemble imparts two separate, usually opposing areas in order to prevent post-treatment re-infestation. The “dirty” area is from where the as of yet untreated tobacco is loaded into the chamber, while the “clean” area is where it is removed after treatment. “The CA chambers contain doors on each side and above the chamber a dividing wall is built to prevent insects from flying from the ‘dirty’ to the ‘clean’ side’.”

Pest Control in Tobacco Warehousing

Courtesy of EcO2 Projects BV

Pest Control in Tobacco Warehousing

Treatment rooms on the “clean door” side at EcO2’s Binh Duong facility, Vietnam, where treated product eventually emerges.

Options for smaller tobacco quantities

Since treatment chamber space is limited, contaminated tobacco has thus to be loaded in batches – which may extend total treatment time to several weeks in case the contents of an entire warehouse must be treated. It also doesn’t solve the issue with normally concurring infestation in the storage facility itself, which would probably require conventional fumigation. However, for smaller tobacco batches, B-Cat and its competitor EcO2 both also offer the option of treatment the tobacco under quick-to-set-up, gas tight plastic tents without the need of constructing fixed chambers. And there also exists the alternative for treatment inside mobile containers in case the client lacks the necessary space for fixed chambers.

The treatment process is continually assessed by sensor-monitoring oxygen and temperature levels, leading to a 100% killing rate of the insects in all their life cycle stages. “Treatment data are automatically registered by our software and can be tracked anytime and from any place by remote control,” Luyten added. Once treatment has concluded, ambient air is pumped into the chamber, with the oxygen level returning to normal within a few hours. “This makes it safe to open the doors and enter the chamber for unloading,” said Luyten.

A mobile CA solution

To wrap things up, B-Cat’s director also filled Tobacco Asia in on a technology developed by mother company CA Technology which ensures that tobacco remains pest-free post-treatment. The VQM packaging system effectively protects treated tobacco from any outside influences, including re-infestation, by utilizing modified atmosphere technology. Luyten: “For example, by packing cut rag under modified atmospheric conditions in special high-barrier liners, VQM helps maintain uncompromised product quality throughout the entire supply chain.”

Please note: The parameters for set-up, preparations, procedures, protocols followed, and other details concerning phosphine fumigation and controlled atmosphere treatment are essentially identical among the companies introduced in this article. By not explicitly mentioning them for each company separately, Tobacco Asia simply tried to avoid repetition.