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Product undergoing CA treatment sealed in bags. Photo credit: Peterson EcO2
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Bartek Drewsnowski, c.e.o., Detia Degesch America. Photo credit: Detia Degesch
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Tobacco beetle infested leaf. Photo credit: Detia Degesch
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CA tent with control unit and N2 bottles. Photo credit: Peterson EcO2
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EcO2 greatly improved its CA chambers with the addition of an overflow system. Photo credit: Peterson EcO2
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Row of permanent CA chambers. Photo credit: Peterson EcO2
Pests cause annual direct losses of around 90,000 tons of tobacco – but it’s preventable.
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. Most insects likewise give it a wide berth. However, there are two notable exceptions. The tobacco beetle (Lasioderma serricorne, a.k.a. cigarette beetle, cigar beetle, or warehouse beetle) and the tobacco moth (Ephestia elutella, a.k.a. cocoa moth, or warehouse moth) are insect species whose larvae just love to gorge themselves on delicious tobacco.
Half a billion dollars of annual losses
Infestations with adult specimens, their eggs, larvae, and pupae can occur at any time, thriving in warm and humid warehouse or shipping container environments and wreaking havoc. Rodents, meanwhile, while not feasting on tobacco leaves per se, bury into bales, building their nests and contaminating the commodity with excrements and carcasses.
“Over the past two years we have seen a considerable growth in tobacco direct losses caused by pest infestations,” said Rodolfo Salvi, sustainability and international relations manager at Salvarat s.r.l., an Italy-based pest control firm operating internationally. Salvi estimated that worldwide around 1.5% of all storaged leaf is destroyed by pests every year. “In concrete figures that’s about 9 million kilograms of tobacco yearly, a weight comparable to the cargo capacity of a mid-sized container ship and worth approximately US$500 million,” he told Tobacco Asia.
The gold standard in fumigation
One of the most commonly used methods to rid storage spaces and shipping containers of infestations is fumigation with phosphine gas (PH3). Detia Degesch Group is a leading manufacturer of aluminum and magnesium phosphide pesticides and a CORESTA member. Apart from its mother company in Germany, the group operates subsidiaries in the US, Argentina, Brazil, Chile, Mexico, South Africa, and – since more recently - Spain, Portugal, and Canada.
“However, our products and services are available in more than 120 countries worldwide through a network of local partners, distributors, and service providers,” explained Bartek Drewnowski, president and c.e.o. of Detia Degesch America Inc., who also asserted that Detia Degesch product solutions are considered the “gold standard” in fumigation treatment and “wherever tobacco is grown, processed, stored or transported.”
Insect infestations are quite easily detectable by placing pheromone traps that attract adult beetles and moths. Counting the trapped specimens can indicate whether an action threshold has been reached that would necessitate fumigation (or other extermination methods).
“Our Magtoxin Degesch plate, which reacts with moisture in the air, is the first choice when fumigating tobacco,” said Drewnowski. “It is preferable to pressed formulations, as it does not contain ammonium carbamate, which may affect the smell, taste and color of tobacco,” he added. The group’s fumigation products react with atmospheric moisture, which then releases phosphine gas.
Adhering to CORESTA guidelines
Using the treatment in any closed spaces requires stringent safety measures, of course, because the agent is also highly toxic to humans. Detia Degesch Group’s trained personnel therefore strictly follows the recommendations and procedure guidelines established by CORESTA, including exposure time, dosage, and temperature standards. Warehouses and other storage spaces also require thorough aeration post-treatment before they can again be accessed by workers. When carried out properly, phosphine fumigation will reliably kill off all four insect life cycles (i.e. eggs, larvae, pupae, and adults) as well as rodents, as allowed per approved labelling.
Prior to treatment, it is important to prepare a fumigation management plan (FMP), which encompasses detailed steps how to seal and close off the warehouse, apply the fumigant, monitor the fumigant concentration, accomplish post-treatment aeration and, lastly, clear the facility for re-entering by humans.
“Once the FMP is established, all openings such as doors, louvers, ventilators, etc. are temporarily sealed using tape, adhesive and plastic sheeting while warning placards are posted at all access points,” elaborated Drewnowski. The typical exposure time is between 96 hours (4 days) and as long as 288 hours (12 days), excluding approximately 2 to 3 days of post-treatment facility aeration.
Ensuring proper fumigation times
During exposure, fumigant concentrations are periodically monitored to ensure an adequate level is maintained. “A lethal concentration of the PH3 fumigant at bale center is achieved within 12 to 24 hours from the time of application,” Drewnowski said. At the end of the exposure period, the storage is aerated naturally by removing the temporary seals. PH3 can be used to treat the entire storage volume in one go, eliminating any pests in the stored product itself, the headspace and surrounding area. The method also can be deployed for infested tobacco batches stored under tarpaulins, which negates the need for product movement.
The issue of phosphine tolerance
Yet Bartek Drewnowski also touched on the controversial issue of phosphine tolerance (or resistance), which he described as “complex and mostly related to the beetles,” meaning that for some reason the tobacco beetle in its various development stages sometimes appears to be much harder to kill than the tobacco moth. “I prefer to look at it as a scale of susceptibility, as resistance implies a condition where phosphine would not be effective,” he said. Drewnowski nevertheless also asserted that “it has been proven that when the CORESTA guides are followed and the insects are treated with the proper concentration, a sufficient exposure period, and at the correct temperature, 100% mortality of all life stages is achievable.” On the other hand, he admitted that certain beetle populations may not be controlled with standard treatment and that a higher treatment agent concentration, longer exposure time, or both, may be necessary for extermination.
Controlling the atmosphere = controlling pests
Fumigation is not the sole option for dealing with warehouse pests, of course. An ingenious method known as controlled atmosphere (CA) treatment makes use of a simple principle: no living organism (leave alone some anaerobic microorganism and deep-sea creatures) can survive without sufficient oxygen. Deprive an organism of that oxygen and it will inevitably die. There are several companies that offer such CA treatments, during which the air’s oxygen is almost completely replaced with carbon dioxide (CO2), nitrogen (N2), or a mixture of the two. Among these providers – and with a global footprint to boot – are Rotterdam-based EcO2 and its sister company EcO2 Vietnam Company Limited, both being a member of Peterson & Control Union.
Low O2 and high N2 do the trick
Infested product is either placed into airtight, permanently constructed climate chambers, mobile containers, under sealed tarpaulin tents or inside large plastic bags. After hermetically sealing the space, treatment commences, being managed online from a remote location using EcO2’s custom-developed soft-ware. Treatment settings such as oxygen, N2, relative humidity (RH), ambient temperature and treatment duration depend on the insect type and development stage, applying EcO2’s own or CORESTA guidelines (see table “CA Treatment Settings”).
The CA method generally is only suited for smaller areas that can be tightly sealed or for product treatment in batches, which must be isolated from non-infested merchandise, pointed out Nguyen Van Nhat, deputy managing director of EcO2 Vietnam. “For pest control of entire warehouses in one go we will apply heat treatment, which EcO2 also can provide,” Nhat said. This particular method exposes pests to an elevated air temperature of at least 50°C for 8 to 30 hours, which is intolerable to tobacco beetle and moth, also stunting their procreation cycle. The treatment time does not include equipment set-up, which usually takes 2 to 3 days. In addition, heat-sensitive products or equipment should be moved out of the treatment area to avoid damage.
A variety of CA set-up options
Customers potentially interested in deploying CA treatment ought to assess their investment options. Constructing permanent treatment chambers on premise can be costly and are really only advisable when it is expected that high volumes of product must be treated frequently. On the other hand, CA containers, while offering largely the same benefits as chambers, are more mobile and can be set up quickly when the need arises. Companies like EcO2 even provide them for short or long-term rental. Meanwhile, tents and bags come in various sizes and, accordingly, can be used for small or large volumes while at the same time requiring a rather low investment. But they also are a cost-effective option when the goal is to prevent stored product from becoming infested in the first place.
Functional improvements in CA treatments
Although CA treatment used to have a reputation for being more cost-intensive than fumigation, EcO2’s Nguyen Van Nhat pointed out the company had greatly improved its chambers with the addition of an overflow system. “When two chambers are operated at the same time, this can save around 28% of cost as the treatment gas discharged from the first chamber can be fed into the second chamber,” he explained. Furthermore, about 5% to 10% of compressor energy can be saved through this optimized gas recycling function. The operating software also has seen some important improvements compared with earlier versions. “We have added more automated control system functions, such as automatic treatment stop and automatic parameter adjustment during treatment,” Nhat said. Lastly, there is the smart monitoring, which employs robotic process automation (RPA) technology to support the monitoring team in controlling treatments more efficiently, including treatment status notifications and failure alerts, all reported via email and/or smartphone phone app.
Getting the PRE.MO.S.T. out of it
It is not uncommon to encounter a complicated infestation situation that requires a fine-tuned treatment plan instead of standard measures. And it is companies like Italian pest control specialist Salvarat s.r.l. that can be tasked with a solution that practically guarantees an end to the menace. For this very purpose, Salvarat has devised a unique strategy that it calls PRE.MO.S.T., an acronym for “prevention, monitoring, synergetic treatment,” according to sustainability and international relations manager Rodolfo Salvi.
Prevention is the “golden rule”
“We see prevention as the ‘golden rule’ because it’s the most cost effective and sustainable action. And paradoxically, once [a client] sets it up correctly by assessing and implementing the methodological plan, [they] might not need us anymore, as an infestation may not occur at all, or if it does against all odds, it will be easy to get rid of, reducing the need for more extensive treatment dramatically,” Salvi said. In more concrete terms prevention means storage flow planning, including establishing a cleaning schedule, eliminating pest habitats, the risk of cross infestation, as well as properly training warehousing employees. “This can reduce direct losses from infestations by up to 95%,” Salvi claimed. Once the prevention plan is running, monitoring stored product is indispensable, going hand in hand with the prevention measures. “Look at monitoring as some sort of an alarm system that will raise a red flag when you need to act,” Salvi said. “Proper monitoring collects data that can be analyzed and evaluated, giving clues how to further improve prevention or, as the case may be, initiate treatment.”
It’s all synergy
That leaves synergetic treatment as part of Salvarat’s PRE.MO.S.T. strategy. “Synergetic” in that context means carrying out carefully selected treatments that actually complement one another in order to ensure quick and reliable pest elimination, as well as establishing conditions that minimize future production downtimes. “It’s a new and quite dramatic shift from the old-fashioned approach of aggressive, high-impact treatment,” explained Salvi. “The key is to reduce the number of treatments and only deploy pest control products that are really needed to deal with the specific situation at hand.” Salvarat is of course so convinced about the efficacy of its PRE.MO.S.T. concept that the company is offering free consultations before clients can decide whether or whether not to give it a try.