Alternatives to Methyl Bromide; Integrated Pest Management in Danish Flour Mills 2. Integrated Pest Management2.1 IPM 2.1 Integrated Pest Management (IPM)Pests Throughout the food chain, the identification, control and extermination of pests in
the food industry requires many resources, from producer to manufacturer, carrier to
distributor together with surveillance and control by the authorities responsible. IPM Mites, insects and rodents can all be introduced in many ways and forms to the food chain, they can enter through their own efforts into buildings, arrive with raw materials, packaging and machinery or in damaged or returned goods. How we prevent their access and how we control the environment in which food is produced, stored and sold, demands detailed planing and a well organised program of preventive measures. This approach is known as IPM - Integrated Pest Management. Decision making IPM is not a treatment or a patented solution, nor is it any special formula to keep away pests. It is a process, an attitude, a system which continually aims at keeping pests at acceptable levels. IPM is a decision making process where all options are gathered together and assessed. The aim of the IPM system is to be able, at any time, to propose effective, economical and environmentally sound solutions to pest control problems within the tolerance limits set by the mill or factory. In certain situations the main guidelines may be at odds, for example, the most effective solution is not always the most environmentally sound. The aim is best achieved by denying pests access or by reducing their chances of survival through thorough preventive measures. The measures include good cleaning and housekeeping practices, regular inspections by qualified personnel, combined with chemical treatments where necessary. Permanent "designing out" of pests through modification of machinery and buildings can much reduce pest pressure. IPM is difficult to define and therefore implement as the terms "preventive" and "treatments" cover such a wide range of possibilities, making it hard to maintain an overall general view, without sifting through numerous details. Choice of method Characteristic for IPM is the openness of the system, it is not at all rigid. Each mill must tailor its IPM system in keeping with its own aims, legislation and chosen parameters, such as health, safety and customer requirements. Chemical treatments, where necessary as part of IPM, ought to be limited as far as possible and the pesticides chosen from an environmentally sound perspective. Residues from treatments must be acceptable to the end markets and comply with accepted Maximum Residue Limits. The choice of a particular pesticide or particular treatment can affect and alter the needs of the system and visa - versa . The situation will be different from site to site, depending upon raw materials, temperature, building construction, condition, age and size, production rhythm, customer demands, attitude of management, workers and so on. Generally speaking, the larger the company and factory site, the more complicated it is, with the potential risk of pest infestation being inherently greater. IPM must therefore be tailored to the specific location and must change in step with changes in the situation. For example, when IPM has been implemented for some time, more emphasis may be put on preventive, pro-active measures than on treatments or re-active measures. To function well, IPM requires a high level of commitment from all concerned. Pest requirements When IPM is introduced to a facility, one must bear in mind that all insects as pests have certain things in common.
An IPM system must continually monitor all areas and aspects of the facility for actual pests and potential risks, including checks on incoming materials, goods and vehicles, whilst at the same time providing preventive control through the use of bait stations, traps, pheromones, good cleaning practices and proofing. If a satisfactory result is to be reached, it can only be done by removing or reducing the root causes and conditions favourable to pests. In this way a more permanent solution can be reached without a dependency on chemicals. Creating fewer environmental or health problems and less risk of developing resistance. 2.2 A brief history of IPMStart of IPM The principles of IPM were first set out about 35 years ago in California, when it was discovered that insects harmful to crops were becoming resistant to insecticides. Also, formerly innocuous insects were becoming serious pests, because some of their natural enemies were being eliminated. Interest heightened in 1972 when The Council for Environmental IPM now Modern IPM programs aim at controlling pests, keeping their numbers and activities below the level where they present economic, environmental or health risks, and are tailored continually to meet each new situation. They use a rational combination of measures to achieve the desired level of pest control. This contrasts with the use of a single measure, e.g. methyl bromide fumigation, which attempts to eliminate pests from an area. Prevention IPM focuses primarily on prevention, first and foremost by physically denying pests access, at the same time having the knowledge and experience at hand to remove conditions favourable to pests, should they somehow enter the plant. All personnel ought to undergo some basic training on the subject. Pheromone lures, traps, temperature alteration, cleaning, treatments, inspection are all factors which play a part in IPM. It should be noted that, although IPM aims to reduce the use of chemical insecticides, it does not exclude their use. In the food industry, consideration of environmental issues together with a growing awareness and concern over the use of chemicals, has led many food producers and chain stores to introduce their own hygiene standards, requiring sub-contractors to document their pest control efforts, preventive measures and insecticide usage. At the same time, this has forced many pest control contractors to re-assess their role in quality control. 2.3 Quality policies and risk assessmentRisks Most companies assess the risks inherent in their particular industry. Mills must evaluate many factors that directly or indirectly influence their production, reputation and profit such as legislation, labour markets, the environment, working conditions etc. Pest control is also one of the factors. Producing safe, uncontaminated food in accordance with legislation must be the primary aim. Thereafter comes the demands of customers and quality control, which are often more stringent than the formal legislative requirements. With these things in mind, each individual mill must tailor the IPM system to reduce any risks involved and to meet the requirements in their particular set of circumstances. Zero tolerance Zero tolerance with regards to any form of pest contamination in food stuffs (be it adults, eggs, larvae, pupae or cast off or broken parts) would be desirable. However the introduction of such criteria in the food chain would be extremely expensive and at the same time extremely difficult to implement. All raw materials that are originally grown as plants, can contain the remains of mites, insects and other pests. If one looks at the pests in question the picture becomes more complex, as some pests are agents of disease or degrade the quality of the product. Apart from this small group, there are many others which on closer inspection have no or very little measurable effect on the products or product production. The opinion of the project group is that careful consideration should be given before deciding upon levels of tolerance. The benefits of zero tolerance would be negligible, and the attainment of such levels would be almost impossible and therefore unrealistic. Important elements of IPM In order that the various elements of IPM can function as a coherent whole, it is vital that: Management assessment Management determine where the likely risks of pest infestation can occur, in consultation with experts in the field where necessary. This will help shape and define company policy and have a direct influence on the standards, aims and tolerances to be set. Policy The policy must be clearly formulated and visible to all employees, to help ensure full commitment and involvement at all levels. Policy maintenance The success of the system rests upon allocating responsibility and maintaining the policy in the future. The commitment of senior management must be visible and they must be available to avoid conflicts of responsibility or misunderstandings, internally or with outside contractors. The involvement of mill staff gives first hand experience and allows problem areas to be identified and resolved quickly. IPM is part of production of a quality product. Resources If there is a contract between the company and an outside pest control contractor, its important that a detailed agreement with clear lines of responsibility is established from the start. Preventive pest control is the aim. However contingency plans should be in place if an acute problem arises. Management must have a realistic perception of preventive measures or active treatments and have access to the resources necessary. Clearly the overnight implementation of a comprehensive IPM system in the mills would be a very expensive exercise. The risks need to be evaluated against the costs involved. The implementation can be carried out in stages, but the main principles of IPM will need to be in place from the start. Companies must precisely define their goals, determine which risks they can afford to run and those they can not accept, and realistically tailor the IPM system to the situation, bearing in mind that methyl bromide is no longer an option. 2.4 Building design and cleaningTwo factors, which have a decisive influence upon a long lasting solution to the problem of pests, are building design and cleaning. Buildings should be structurally sound and designed in such a way that pests are not encouraged and are easily monitored. See 2.5 Internally things should be arranged so that all areas are accessible and easily cleaned. New constructions When new facilities or structural modifications are contemplated the exclusion of pests must be given a high priority, cracks, crevices and potential pest harbourages must be known and "built out". Professional advice may be necessary. Areas of high risk Dividing the facility into areas of risk, according to the sensitivity of the area, or products therein, can help maintain a heightened awareness and greater respect for the measures taken. Cleaning routines At the start of an IPM program, the mill and machinery should be audited to determine where there is harbourage for infestation and where infestations are most likely to affect the product chain. Engineering modification of the high risk areas, at least, should be considered to build out pests or allow fully effective cleaning. Good sanitation is the first line of defence. Detailed cleaning routines should be drawn up and employees trained and encouraged to follow the highest standards of hygiene. Responsibility for cleaning should be delegated to individuals and their working areas. An example of such a cleaning routine can be seen in appendix 3. Many more points would of course be included in an actual situation. 2.5 Inspections2.5.1 Factory inspection Effective inspections, on a regular basis, through thorough competent surveillance of the whole facility both inside and outside, are necessary if the system is to function properly. Site plan A site plan must be used, clearly defining individual areas of the whole site. Areas should be numbered or named in such a way that misunderstandings do not occur. All baits, traps and pheromone traps should be charted on the plan with a number and symbol as to their type. Check lists must be drawn up for each type of trap giving a complete view of the situation and enabling pest populations to be monitored and compared with previous findings. Scope of inspection If an outside pest control contractor is employed, clear lines of communication should be agreed upon so that all findings or comments by employees concerning pests, in the periods between routine inspections can be discussed and acted upon. Inspections should cover all aspects of the site and include inspection for all types of flying and crawling insects, rodents, birds, condition of building, potential harbourage, housekeeping, storage, incoming goods and raw materials plus any other factors which could encourage pests. 2.5.2 Inspection check lists The following section includes advice and guidelines on check lists and inspection reports which must be as comprehensive as possible whilst at the same time being clear and easily read. Examples are given below:
The inspector should be aware of potential hiding places outside, examine the exterior closely for cracks, crevices and defects which would allow pests access. The outside area must be kept tidy. Pallets, containers, building materials, used machinery and so on should, if necessary, be stored away from walls and off the ground. Lawns, flower beds and bushes should be kept tidy and away from walls. Eaves of roofs examined and, if necessary, bird proofed. Silos Flour and grain is often stored in silos. As the commodity may remain in the silo for longer periods, infestation can occur. Silos must be inspected frequently and, if necessary, cleaned. Likewise the commodity, silo top and bottom should be inspected frequently (at least once a month). Design Flow path. Finished product should not be stored close to raw materials. This is to avoid cross infestation. Refuse and container area The flow of factory waste should be checked from start to end. All areas with refuse are possible hiding places for pests. The refuse and container area should be laid with concrete and supplied with a drainage gully and hose pipe so that it may be cleaned frequently. Refuse container The refuse containers should have tightly closing lids, and be large enough to prevent overloading. They should arrive clean, and if held on site for longer periods, they should be cleaned often . Small waste containers should be sited away from walls and proofed against rodents and flies. Refuse Refuse that does not contain food should also be stored as above to avoid providing hiding places for pests. Guidelines for emptying refuse should be prepared. Flagged areas and drainage systems Flagged areas should be well drained, as water often attracts pests. Holes, cracks and crevices should be properly sealed, especially around refuse areas. Weeds Heavy weed growth gives good hiding places for rodents. Weeds, flower beds etc. should be removed from around buildings. Generally there should be no vegetation within 1 meter from the building that pests can hide in. Preventive rodent control Beside external tidiness, the siting of permanent rodent bait stations is an excellent method of preventive rodent treatment. The bait stations should be sited outside, along the outer walls at intervals of 15 meters surrounding the building. It is especially important to site bait stations at the entrances to buildings, containers and refuse areas. Bait stations should also be sited along the perimeter fence. Note, rodent baits can be a source of infestation for insect pests. Baits should be checked regularly for infestation or treated with a residual insecticide. It is essential that effective procedures are in place to prevent any contamination of product by traces of rodent bait. Preventive insect control Insects, usually flies, can indicate poor hygiene. Once again cleaning is necessary together with a broad vegetation free belt around the building, and fitting windows with insect netting. Cracks and crevices should be sealed to prevent insect access. Ad.: Building structure Preventive rodent control Inspect the building inside and outside for holes and gaps where rodents can enter. Doors, sliding doors, windows and ventilation pipes must be kept closed when not used. They must fit the framing so that no cracks or holes are larger than the diameter of a pencil. A metal plate on the lower part of wooden doors and gates prevents rodents from gnawing through. Rooftop ventilation pipes should be secured with galvanised metal netting. Preventive insect control Check that all windows have intact insect netting, with a 1/10 gauge mesh. If there are plastic curtains these should be checked for possible defects. Automatic doors are recommended. Preventive bird control Birds can contaminate food and be instrumental in the spread of disease and insect infestations develop in nesting material. Birds must be prevented from nesting on roofs and under eaves. Doors should be equipped with plastic strip-curtain preventing birds form entering. Modify buildings to eliminate roosts and nesting sites. Check windows, as a defect skylight often is the cause for internal problems with birds. Roofs Food particles e.g. dust escaping through the roof ventilation gaps, often causes pest problems (mice, rats, birds etc.). The roof should therefore be kept clean and the ventilation gaps be provided with dust filters and galvanised netting at the mouth. The filters should be cleaned frequently and if necessary replaced. Skylights should be provided with a lock and be tight fitting. Inspection of the roof is essential. Light Insects, which are attracted by fluorescent lights at night, can become a problem. If so, the problem may be reduced by replacing the fluorescent tubes with tubes without GROLUX. Other areas All other areas such as compressor rooms, pump rooms etc. should also be inspected. Indoors Many pest problems arise because goods are stored close to or up against a wall impeding cleaning, and creating harbourage. Goods should not be stored closer than 50 cm to walls and preferably well above the level of the floor. Stores Electrician and Millwright stores often have items that are not moved for long periods and may provide habitat for pests. They need periodic inspection and cleaning. Raw materials Inspection of raw materials include 2 kinds of inspection. One is the
inspection/spot test of the goods and packaging. The other is inspection of the raw
material supplier. Suppliers of raw materials, often from distant countries, do not always
show due consideration to pest control. Pests are often brought into a plant in this way. Raw materials or finished products for ongoing distribution should be inspected on arrival and before entering the plant (se app. 6, page 48). The packaging/pallets must be inspected for rodent activity or droppings as well as
evidence of insects. Samples should be taken of all goods arriving by ship or tanker and
kept for a sufficient length of time for eggs to hatch. Finished products The finished product store is the last stop before delivery to the customer. Therefore this store must be easy to inspect, and clean and organised in such a way that any product can be traced back to its production time, line and source of raw material. The plant should be organised so finished products are not stored close to raw materials to prevent the risk of cross infestation. Returned goods Goods are often returned because of damaged packaging, elapsed sell-by date etc. Returned goods are often stored randomly, together with other goods, and therefore present a risk of infestation, as pests have easy access when the packaging is damaged. It is essential that returned goods are stored in quarantine storage and that the goods are examined for evidence of pests or other contamination. Packaging The buyer should impose conditions on the packaging supplier. It has often been proved that pests are brought into factories with the packaging. This must therefore be inspected along the same lines as incoming raw materials or other incoming goods. Corrugated cardboard packaging is particularly favoured by pest moths as a pupation site. Rigorous hygiene and stock control should be carried out in the packaging store. Walls Walls should be of an easily cleaned material with mouldings at the floor to avoid dust accumulations and ease of cleaning. Look for cracks and crevices around pipes and ventilation openings in walls. These cracks and crevices must be sealed to prevent providing insect breeding and hiding places. Floors The floors should be impervious. All cracks or crevices must be sealed. The sealant must have sufficient flexibility to accommodate normal thermal and other movements of the building. Be aware of places with "false floors" e.g. concrete with a suspended wooden floor. The cavities between are likely to create pest problems. Rodents will hide there and insects may find food/dust residues and live and breed there. Suspended ceilings Suspended ceilings often cause pest problems and should therefore be constructed in a way that enables access to the cavities. All crevices should be sealed, in order to avoid dust accumulations and eliminate insect hiding places. Cracks around ventilation shafts should be sealed. Light fittings should be supported at least 2 cm clear of ceilings and walls. Lift shafts Lift shafts should be clean and pest free. They should be inspected frequently for possible damp problems, causing pest infestation e.g. mould beetles, as well as food residues which could attract pests. Siting of goods, machinery etc. All machinery, goods etc. should be sited away from walls and off floors to enable cleaning under and behind them. Floor drain Floor drains often attract pests. Rats can gain entry as well as cockroaches, fruit flies, mould beetles etc. The drain should be kept clean and be covered with a screwed steel grating that can be removed for cleaning purposes. Sanitary installations Condensation, obstructed, broken or damaged pipes can all cause pest problems (se above concerning floor drain) as such conditions are often favourable to pests. Ventilation systems Production odours can attract pests. Therefore, all windows should be fitted with insect netting. Louvers must be cleaned and the integrity of the seals checked when closed. Poor ventilation can cause many problems in mills e.g. condensation, mould and smells. A poorly constructed ventilation system with defective, missing or saturated filters can accumulate enough dust and food residues to attract insects and other pests. Ventilation shafts and pipes should be cleaned frequently. Modification may be needed to allow easy access for thorough cleaning. 2.5.3 Traps and indicators Pheromone traps At present some of the most effective tools in an IPM-system are pheromone traps. A pheromone is a chemical or a mixture of chemicals secreted by an individual which in a gaseous state causes a reaction from another individual of the same species. Progress within chemical analysis and synthesis methods has made it possible to
identify and reproduce the chemical compositions that form the pheromones some insects
use. The pheromones are specific for each species and are only used in very small amounts.
Currently there are synthetic pheromones for the most common pests in mills. Indicators The traps are used as indicators. They indicate the presence of a certain species of pests. Based on the number of adults found, the size of the infestation can be estimated and
the risk of spreading assessed, giving a general view of the situation. Electric insect killers In less dusty areas i.e. store rooms etc. electric fly killers may be used, attracting flying insects with UV-light. The insects are trapped and killed in a high voltage grate behind the fluorescent tubes. The insects are collected in a tray at the bottom of the device and should be identified and counted. Electric insect killing traps should not be sited in areas with high concentrations of flour/sugar dust because of the risk of a dust explosion. Poorly sited traps can attract insects from outdoors and so cause a problem. It is important that electric fly killers are only used in an IPM-system, where insect netting is in place at windows and doors and other preventive measures are installed. Servicing of traps All traps and bait stations must be inspected regularly, contents or evidence noted on the department check lists, and the bait or pheromone replenished, if necessary. 2.6 StorageAs previously mentioned, it is important to inspect goods for pests prior to items being stored. It is also important that storage is carried out on well organised shelves, raised off the floor to allow immediate, easy removal of spillage and to facilitate and encourage visual inspection. "First in - first out" To prevent pests reproducing on site, it is essential that the storage principle "first in – first out", for raw materials, packaging, products etc. is adhered to, allowing goods to be stored for the shortest possible time. 2.7 Training of personnelPersonnel IPM in the mills should involve all personnel . Each individual should be conscious of his/her responsibility to report evidence of pests or conditions that may cause pest infestation. Training All personnel should receive some training concerning the life cycle of pests, cleaning, housekeeping, lines of responsibility among personnel and management, company policy and aims. Seminars The training should provide each individual with enough information to be able to carry out their duties in a professional manner. 2.8 Alternatives – not fumigantsOptions A brief look at some of the available options that may be used in an IPM-system
follows. Some are more relevant than others, as new ways, means and methods are developed
all the time. It is therefore important for the IPM-system user to keep abreast of
developments and choose the most appropriate methods in each situation. 2.8.1 Pesticides Cold foggers Space/fog treatments are carried out normally with synergised natural pyrethrum. It is sprayed as a fine fog/mist into the air space, the mist remains suspended in the air for some time and kills the insects it comes in contact with. Fogging is of limited effect as it cannot penetrate the places where the insects hide and develop: goods in sacks, machinery, cracks etc. It has no residual effect and may kill beneficial insects, particularly wasp parasitoids of pest moths. Surface treatment Surface treatments with chlorpyrifos or deltamethrin play a large part in preventive treatments in Denmark. These insecticides are sprayed into cracks and crevices where insects may hide or as a continuous belt in places where insects contact the insecticide when they wander. Knowledge of the insects’ habits and a careful application of the insecticide is required, in order not to contaminate surfaces where foods is handled. The advantage of these insecticides is that they are residual - even for months. In a mill they may quickly become inefficient if they become covered with flour dust. 2.8.2 Diatomaceous earth Diatomaceous earth, a very fine inert dust, consisting of the fossilised remains of single-celled plants called diatoms is obtained from mineral deposits. Slow residual Diatomaceous earth formulations are slow acting they are thought to cause death by
desiccation as a result of disrupting the waxy outer layer of the insect cuticle. 2.8.3 Biological control All insects are pests Many insects or mites live off other insects, either as predators or as parasites on the eggs or larvae. This fact can be utilised for biological control where predators or parasitoids are released in a controlled manner in areas with pest problems. Additional insects are undesirable in food factories and more study is needed. Food factories and predatory insects "The Danish Pest Infestation Laboratory" is at present doing research on the control of the Mediterranean flour moth in mills using these techniques. 2.8.4 Freezing Small valuable Consignments It is possible to freeze goods in order to eliminate all stages of insects. At present
the method is only relevant for small amounts of valuable product. Speed is important and limits the amount of goods that can be frozen together without extending the freezing time. 2.8.5 HTST Heat treatment over a short period High Temperature Short Time is a method using high
temperatures to treat cereals e.g. to sterilise grain for mink feed. In Denmark tests have
been made with HTST for killing insects with air temperatures up to 700°C for 10 seconds
without damaging e.g. the germination or baking qualities. 2.8.6 Entoleters Cleaning of grain Entoleters are impact machines, material is fed into a rotor revolving at high speed and flung outward onto studs on the walls of the machine, the speed can be adjusted to avoid damage to sound kernels, however damaged kernels and insects are broken on impact and separated from the bulk. Entoleters are best used to disinfest milled products. 2.8.7 Cold storage Cold storage Insect pests typically require temperatures above 14°C in order to be able to multiply. Below this temperature many pests slowly die off, with eggs, larvae and pupae often susceptible to moderately low temperatures. Some adult pests and those able to enter a resting stage known as diapause may persist for months or even years. Storage at below 14°C and under dry conditions is a useful management tool for raw materials which are at risk of carrying a low level of infestation. Subsequent processing may eliminate the pests while the cold prevents their spread or multiplication in store.
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