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Pest management in a mill

05 January 20187 min reading

“Pest management is not limited to a fixed or enclosed area. While it may be the first objective to control rodents or insects in a high-risk area such as food production or control room, a real pest management program also considers what is happening in the surrounding areas.”

peterPeter de Weert

International Pest Control Manager Control Union

The most famous Dutch football player Johan Cruyff once said that that it is very difficult to keep things simple. While his quote was related to football we can, with a little fantasy, extrapolate this to Pest Management as well. Pest Management as a business and as a practice can become complicated with specialized tools used to target very specific problems. We will touch upon some of them in this article. The main point of this article however, is that the basics of pest management are in fact rather simple; good general hygiene and strong but easy to follow procedures to keep issues manageable. The very basis is even simpler: Without possible entry points pests cannot target certain areas, and without food they will not settle.

The above statement is the same for basically all pests, but here we will use as an example two types of pests that target the mill: rodents (rats and mice) and stored product insects like the flour beetle (Tribolium confusum) and the Indian meal moth (Plodia interpunctella). As pest controllers, we visit all kinds of businesses with less or more challenges and risks involved. In our field of work the mill can definitely be considered of ‘high maintenance’ as it is often a complicated building with many potential entry points and with delicious food source for pests.

The Pest Management basics Three initial realizations are important when looking into pest management:

1. Pest management is not a problem of the pest controller alone. While he or she may be the expert, we are only passing by on longer or shorter intervals, hence we will always have to rely on observations of people working in the certain area every day, to understand specific problems. This should not only be the quality manager! 2. Pest management is not limited to a fixed or enclosed area. While it may be the first objective to control rodents or insects in a high-risk area such as food production or control room (electric cables), a real pest management program also considers what is happening in the surrounding areas. 3. Pest management is a combination of 3 actions: Prevention, Monitoring and Control.

Here are the steps of all parties involved to guarantee clean and safe food is produced in a mill.

PREVENTION A good pest control program primarily aims to make an installation pest-proof. We have however to respect the legislation as in some European countries nowadays there are specific rules on what can be used to target pests in the perimeter of buildings. This new legislation aims to prevent the use of unnecessary toxics being added to the surrounding ecosystem of a mill. So rodenticides may not be used even in bait station regularly, except if a specific infestation needs to be addressed. These limitations put extra emphasis on making premises impossible to enter by pests. There are basically two ways for pests to enter a building: by themselves from the outside or via infested cargoes. To prevent entering from outside, simple, but often overlooked measures can be taken. Even the smallest crack or hole should be closed (mice only need 0.5cm to enter), all windows should have insect screens, all walls should be sleek and doors should be kept closed. A professional pest controller can identify the weak spots and put procedures in place in the installation through a risk analysis.

The second way pests can enter the premises is on an infested cargo. Especially insect eggs are very hard to spot, but can easily develop a wide infestation. To prevent infested cargoes from entering the production, thorough procedures and trained personnel need to be in place. As there are many points in the supply chain where infestation can take place, the procedures should cover all these parts. A few examples include the inspection of grain cargoes for insects, the inspection of empty vessels, trucks, rail trucks before loading and the inspection of empty silos and warehouses. Professionals must do the sampling and analysis of cargoes at various points in the supply chain and when an infestation is found, the elimination must be complete.

Traceability of a load is of key importance and that includes the list of inspections and treatments performed.

MONITORING Pest management starts with a risk assessment of the potential pests and of the potential entry points. That leads to setting up a system of monitoring traps that are regularly inspected. The time that a pest controller just put poison in bait boxes and sprayed all surfaces of a mill with contact insecticide on every visit has passed. Nowadays we monitor the pest activity at regular intervals using IPM (Integrated Pest Management) tools to identify the pest activity and analyze the level of infestation.

In every visit the pest manager validates the risk analysis (RA) of each area. Rodents need water, food, shelter and relative quietness. The RA shall focus on points that offer these conditions. During each visit the pest manager looks for rodent proof like nests, droppings, prints, bite marks and potential entry points. Monitoring tools for rodents include detection powder, glue traps, mechanical traps and bait consumption. Insects are monitored by pheromone or UV (ultra violet) traps. The pheromone traps use lures that contain sexual or aggregation pheromones, while the UV traps attract flying insects with light. Other examples include pitfall and adhesive traps. Traps must be checked regularly as an insect population can grow rapidly when the conditions are favorable.

When designing an IPM system, a professional will consider several issues. For example a bait box shall be made of hard plastic that does not contain toxic substances, is resistant to uv radiation, is lockable, tamper proof and must be secured on a wall or floor. Spreading of the toxic substances inside or outside must be totally avoided. In this context, positioning rodenticide out of boxes or glue surfaces and snap traps in the open is not regarded as good practice. A killed rodent becomes a microbiological risk, while exposed rodenticide is a major chemical risk and a threat to non-target animals as birds.

CONTROL There are several ways to kill insects in production areas and warehouses. Chemical control is based on two broad classes of insecticides: A) contact insecticides and B) gaseous fumigants Contact insecticides are mostly used today through spraying or fogging on surfaces like walls, floors or directly on grains. Each chemical has a specific label and registration that describes the scope of use. Insecticides act as neurotoxic, by contact, inhalation or ingestion. The contact insecticides have a residual effect. This means that they are effective for a longer period of time after application. After the application the insecticide becomes invisible and therefore it shall be carefully applied.

Fumigants are gases released from cylinders or from solid forms through reactions. To perform well, fumigants need to be applied in gas tight environments, as their action is a combination of concentration with time. Monitoring of fumigants is essential to achieve effectiveness and avoid risks of surviving insects or on people health.

• There are additional IPM methods for controlling insects in a mill and in the grain that are not chemical but are very successful. These are: Heat treatment of the mill area and of the empty silos (above 56C no pests survive), • Controlled atmosphere on products (grain and flour) in chambers or silos (below 1% oxygen no pests survive)

In case of a mill, food quality and safety are at the top of the list of objectives. Pests need to be controlled effectively and safely. So the need of a top IPM professional is highly important. But keep in mind: it all starts with good hygiene and procedures. Keep it simple. After all football is so much more complicated than Pest Management!

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