Problems caused by flour mites

Acariens Tyrophagus putrescentiae

Flour mites are often present in food products (dry industrial foods such as meat, cheese, dry fruits and cereals), in which they often proliferate when exposed to the correct conditions (excessive heat and humidity). They can be found in industrial stocks or in kitchen waste. One of the key problems is how difficult it is to reach the mites within their biotope (e.g. inside cracks in meat, in dry fruit, silo grains - where the mites lay their eggs).

The consequences of an invasion

Flour mites cause significant damage to food stocks. For example, some grain silos lose an estimated 30% of produce. They can infest up to 40% of cereals, flours and poorly wrapped biscuits. In Horeca, 45% - 80% of bins are filled with food waste, a significant proportion of which was ruined by mites. They pose a serious problem, both on an environmental (excessive use of natural resources), ethical (devaluation of food) and economic (unnecessary spending and treatment of waste) level. The cost of this food waste is not solely generated by waste management, but also by the products bought and the hourly cost of labour thus wasted.

They can also pose hygiene problems. Moreover, their metabolic waste products (excrement, moulting residue) can trigger respiratory, food and skin allergies (14.5% of people working in the ham industry, 11% - 33% of bakers and 16% of farmers). They are also capable of provoking skin or gut irritation. Dogs and cats are also affected by mites and may suffer from infestations.

The problem is far from being resolved

These flour mites reproduce on ham and salted meat during their maturing process, as well as on cheeses, dry biscuit food for dogs and cats, dry food for humans and in grain silos,... There is therefore great market potential for products aimed at controlling mites in food stocks. Pesticides are the main weapon used by food storage managers in the fight against flour mites. However, they have drastic effects on human health (EFSA, INSERM (French Institute of Health and Medical Research) and studies show that mites can form a resistance to insecticides within 4-5 years. It is therefore necessary to constantly carry out further research and find new biocides.

The problems caused by these flour mites (destruction, allergies, hygiene) are far from being resolved. Fundamental industrial research must be put in place to control the excessive presence of these creatures, which are responsible for damage to food stocks and triggering allergic diseases in the work environment, as well as being indirectly responsible for problems caused by the use of pesticides.

Flour mites cause significant damage to food stocks.

What are flour mites?

Acariens Tyrophagus putrescentiae 2

The most common species of mite found in food reserves are Acarus siro, Tyrophagus putrescentiae, Lepidoglyphus destructor and Glycyphagus domesticus.

Barely visible to the naked eye, these mites are arachnids (related to the spider) and measure less than 1 millimetre (between 0.2 - 0.3mm in length).

They are able to reproduce in all food types and at all stages of food production, therefore in grain silos, bags of flour, muesli, dog biscuits and cheese.

Acariens Tyrophagus putrescentiae sur flocon davoine muesli

These mites need a warm and very humid environment to grow, preferably 25-30°C with 80-90% relative humidity.

They live in symbiosis with mould, which they feed off and spread themselves. When swallowed by the flour mite, the mould spores are not broken down by digestion, rather they are further dispersed. The mite therefore the fungus as a food source, and quickly scatters it across a greater surface area. We generally underestimate the importance of managing mite populations in food stocks because their presence goes largely unnoticed. However, the consequences of said presence, particularly the rapid proliferation and spread of fungi, are definitely visible to the naked eye. In other words, the damage caused by the presence of mites is solely blamed on fungi. Food storage managers will throw away food that has been turned mouldy by mites without trying to control the cause of the mould’s rapid spread.

These mites need a warm and very humid environment in order to grow.

Current solutions

Depending on the type of food affected, flour mites can be eliminated by:

  • cold (freezing): This is the most effective method but it is not suitable for all foods (e.g. cheeses).
  • replacing oxygen by injecting nitrogen into hermetically sealed storage bags: This method has two drawbacks. First, it is only moderately effective because it is impossible to remove all the oxygen and the remaining quantity still suffers from the effects of mites. Second, it only works if the bag remains unopened or un-pierced.
  • pesticides:  Pesticides are the main weapon used by food storage managers for fighting against flour mites. However, they have drastic effects on human health (EFSA, INSERM). In fact, many of these pesticides have recently been banned and many others may yet be withdrawn from the market. To this effect, a recent French parliamentary report noted that the dangers and risks related to pesticides were underestimated and that there was insufficient protection against them.

The most commonly used pesticides for mite eradication are usually products with a pyrethrum base, which is often labelled as harmless. In reality, toxicological studies are generally carried out over short periods, without measuring the impact of the accumulation of these biocides on the human organism. Additionally, studies show that mites can become resistant to insecticides within 4-5 years. It is therefore necessary to constantly carry out further research and find new biocides. However, the need to introduce complex chemicals that are not allergenic themselves somewhat reduces the scope of investigation.

Pesticides are the main weapon used by food storage managers for fighting against flour mites.

Our solution

We know it is possible to produce less food waste, limit allergic diseases and generate greater profit by reducing the amount of products destroyed by flour mites. This is why we are going to study the social environment these arachnids live in and the way they communicate. Our aim is to find ways of attracting them and eliminating them without the use of toxic products, much like the method we used to develop Acar’up. These relatively unknown and poorly studied creatures communicate with each other through the use of chemical molecules, which we can use as bait to lure them into a trap.

Once developed, these lure traps will provide an appealing alternative for food storage managers. Derivatives of this type of product will depend on the food type requiring protection. They will need to be adapted to each food production industry, including salted meat, other meats, cereals, dog and cat biscuits and cheese.

Once developed, these lure traps will provide an appealing alternative for food storage managers.

Did you know?

For many centuries, cheese producers have planted flour mites (Acarus siro and Thyophagus casei) on the rind of their cheese to encourage the maturing process. Such is the case in the production of Velay (Auvergne, France), aged Mimolette (French Flanders) and certain Tommes (Savoie, France). How do the mites add that inimitable acidic taste that foodies go so crazy about? It remains a mystery, but the success of these unusual markets and their artisan cheeses is a clear demonstration of their unique contribution.

Link to find out more about pests of all kinds

www.acari.be