1: Overview and Life Cycle
2: Implications of Infestation
3: Monitoring Methods
4: Treatment by pesticides
5: Exzolt – Treatment via the drinking water
The existence of the Red Menace
Poultry Red mite (Dermanyssus gallinea) present a damaging and highly persistent parasite that effect bird health, welfare and in turn production in the laying environment. The Red Mite live in the furniture and in the structure of the building emerging to feed on the hen for periods of 30-60 minutes (Maurer et al 1988) before retreating to a crack or small dark area. The average lifespan is in the region of 20 days for a feeding mite however they have been known to remain dormant for periods of up to months. It is important to understand the scales of infestation as a moderate infestation alone is equivalent to 50,000 mite per hen and a severe infestation can see this rise to as many as 500,000 mites per hen (Kilpinen et al., 2005). The increasing prevalence of red mite in the laying environment is most likely due to a number of advances that have been made to make the laying environment increasingly favourable for the bird, the lower ammonia levels due to the removal of flat deck houses, control of shed temperature due improved insulation and heating. Th ese atmospheric changes when combined with the greater intricacy of the modern laying systems leads to a situation where there are more areas for colonisation which hard to reach with spray pesticides and even during the cleaning period at the end of lay.
“It is the preference of red mite to occupy free range or barn systems as opposed to caged, since a greater number of potential hiding places can be sought. A problem which will therefore be amplified within the EU with the impending ban on production in laying cages. This, in conjunction with concern over resistance to acaricides, toxicity risks and acaricide withdrawal, make control particularly problematic and financially draining for producers.”
S. Arkle 2007
“Red mites 66. Red mites in low numbers cause irritation, making birds restless and prone to injurious pecking. Large numbers of mites can cause anaemia, pale comb and wattles, reduced egg production and progressive weakness until death. Younger birds and chicks are particularly susceptible to rapid anaemia and death. The red mite lifecycle from egg to adult can be as little as a week and once there is a problem in the flock it can be difficult to bring under control. 67. A clear monitoring and treatment protocol devised with a veterinary surgeon and defined in the health and welfare plan should be routinely carried out and records kept. See also paragraphs 112 to 117. Equipment and furnishings should be checked for mites; simple mite traps can be placed in the house in key areas to monitor levels. The comb, leg and breast skin of birds, including any found dead, should also be checked. A visible clumping of mites or blood spotting of eggs denotes a severe infestation”
DEFRA Code of Practise for Laying Hens and Pullets 2018
In order to properly treat and attempt to control Poultry Red Mite an understanding of the life cycle is important.
Stage 1: Eggs are laid by the female red mite with a total of 30-50 over a lifetime (Eddy Teenstra Wageningen Livestock Research).
Stage 2: 2-3 Days later the egg hatches and the Larvae emerge.
Stage 3: 1-2 Days later the larvae enters Protonymph stage and will take its first feed.
Stage 4: 1-2 Days later the Protonymph enters the Deutonymph stage of development.
Stage 5: 2-3 Days later the final growth stage is reached and the adult female red mite will begin to lay eggs again.
It is due to this fast growth sequence that red mite populations are able to very quickly expand. In favourable conditions (which many laying set up currently offer) the red mite can go from egg to adulthood in 7 days.
2. Implications of Infestation
Each individual infestation will carry with it a unique combination of the below which will be due to levels of infestation, health of the birds and age. However the symptoms below are common from our observations of the UK laying industry. It is estimated that in the EU red mite infestation has a financial cost of .45 Euros per hen housed (Eddy Teenstra, Sustainable control of Poultry Red Mite 2018.) this is due to the combination of a ban to beak trimming and longer period of housing.
As an observation on the relationship between red mite and disease from laying farms we have worked on that have used the Exzolt product which is a fluralaner based acaricide with a near 100% kill effectiveness we saw a dramatic reduction in E-coli transmission.
Disease vector: The nature of the Red Mites consumption of blood and repeated feedings represents a significant threat of transfering blood borne diseases.
Blood Loss Anaemia: This is due to the feeding of the red mite and can cause weight loss, lethargy and additional mortality.
Stress, feather loss and packing: The heaviest infestations of red mite in our experience can be clearly observed around the nest boxes and the metal furniture of the system. As the red mite are most active at night this in turn could potentially lead to an inability to rest, avoidance of nest boxes and irritation causing feather pecking.
“You can’t manage what you can’t measure” Peter Drucker
There are 2 validated principle methods of monitoring red mite levels in a poultry house.
The first method is the use of Red Mite traps that are placed at a set ratio to the number of adult birds housed for a period of a minimum of 48 hours. The traps are weighed on a calibrated scale that reads accurately to a single milligram (1/1000 of a gram) and the placed strategically where the red mite populations are evident. The traps are then retrieved and re-weighed which allows the software to create a reading of the level of infestation. This method however can be completed and simply visually assessed to ascertain the levels.
We have carried validated testing on over 400 different poultry flocks and this has allowed us to gain some valuable insights into the behaviour and speed of growth of Poultry Red Mite. As part of the services Rosehill offer, we test different rearing and laying systems to ensure they are red mite free and as a method of verification that the Exzolt treatment worked correctly.
The second method is the use of electronic red mite counting devices which have been developed in Europe. The Automated Electronic Red Mite Counter, this is a system that gives real time readings of Red mite levels which in turn allows the timely treatment of the birds when the red mite population reaches a level where it impacts production. This technology has not been used in the UK as of yet as far as I am aware but in principle it is a valuable tool when used correctly.
However it should be noted that you do not need to use a validated method to observe the level of infestation, a stockman will be well aware of when the population is getting high from markers such as restlessness, red mite marks on the eggs, visible populations and some good friends of mine even say they can smell the red mite present!
“You can’t manage what you can’t measure” Peter Drucker
Treatment of Red Mite Infestations
Until recently there was only one viable method of controlling red mite and that was via the spraying of Acaricides. This is a job that does require groundwork and adequate time to be carried out effectively due to the medium through which the active ingredient reaches the bird. As all spray treatments are suspended in water a common cause of limited results is either inadequate volumes of product and liquid being used, or the system being excessively covered in dust. In order to get between the joints and in the crevices of the system where the mite is present it is important there is adequate solution and the dust will absorb this rendering it useless. Thus, sweeping and blowing down prior to spraying can help in the effectiveness of the treatment. When spraying with birds in lay with products that have a chemical element it is vital to adhere to the recommended dosage levels to prevent egg residues and to alternate the products that are being used, the active ingredient is the principle element that needs to be rotated to prevent resistance.
St. David’s Poultry team distribute Dergall which is particularly useful for application in lay as it has a physical mode of action which works via a three-dimensional immobilising polymetric structure (3D INS). This mechanically immobilises the red mite and blocks the mite’s spiracles (through which they breathe) causing death. Due to the mode of action there are several key benefits over chemical pesticides;
- Can be sprayed onto birds
- Safe for humans and environment
- Cannot cause resistance
- Antibacterial properties
- Does not penetrates eggs
As a guide this would be applied in the evening at a rate of 150 litres per 16,000 bird free range unit. This would then be followed with a treatment 7 days later which would further decrease the population by killing the new generation of red mite that were not developed and mobile at the time of the initial treatment.
- Drinking Water Treatments – EXZOLT
In 2017 MSD Animal Health successfully launched the Exzolt Fluralaner based product which is applied in 2 doses spaced seven days apart through the drinking water at a rate of a .05ml Exzolt per kg of bodyweight per dose. It works via the action of the Fluralaner Molecule which kills via its inhibition of the red mite’s nervous system causing egg laying to cease and death with a period of 4 hours after consumption. The dosage remains active in the bird’s blood for a period of approximately 21 days which spans 2-3 life cycles. The product is licensed for use while the birds are in lay and can be used at 3 monthly intervals however this is not usually required.
Having treated several million birds with this product in a multitude of environments we at Rosehill and St. David’s have worked extensively with MSD to create a system of Bio-Security checks and actions to be carried out alongside the treatment to help ensure protection that lasts. We aim to personally attend all applications and then can properly advise on subsequent treatments. An adaptive and holistic approach to eliminating the entire population has worked particularly well in colony environments.
The usual course of events following the first treatment is as follows;
1-day post first treatment: large numbers of dead red mite are evident however there are still adults functioning that have not fed yet and all life stages of the mite
7 days post first treatment (day of 2nd application of Exzolt): only the bright red Mite are present and mobile, this is due to the Haemoglobin content of the freshly fed on blood within the mite. The period in which the mite becomes a darker colour ceases to take place as the mite is dead before this can take place.
14 days post first treatment: Red Mite become especially hard to find.
21 days post first treatment: Red mite are not evident in any areas of the house.
The effectiveness of the treatment stems from how thoroughly the site is cleaned prior to and during treatment in areas where chickens are not present. The egg room and storage areas can be harbours for red mites that may re-infest the poultry house once the birds are 28 days post treatment and no longer hazardous to the mite. By thoroughly cleaning all areas and ensuring that birds are present in all areas during treatment using pens the effectiveness of the treatment can be dramatically increased.
We assist in the design and implementation of a holistic treatment plan which can dramatically reduce the burden on a site and in turn may contribute towards increased production and bird welfare.
Immunological effects and productivity variation of red mite (Dermanyssus gallinae) on laying hens- implications for egg production and quality
S. Arkle (a1), J.H. Guy (a1) and O. Sparagano (a1) September 2007
Field evaluation of poultry red mite (Dermanyssus gallinae) native and recombinant prototype vaccines
Author links open overlay panel KathrynBartleya FrankTurnbullaHarry W.Wrighta John F.Huntleya JavierPalarea-AlbaladejobMintuNathb1 Alasdair J.Nisbeta
Kilpinen et al., 2005
O. Kilpinen, A. Roepstorff, A. Permin, G. Norgaard-Nielsen, L.G. Lawson, H.B. Simonsen
Influence of Dermanyssus gallinae and Ascaridia galli infections on behaviour and health of laying hens (Gallus gallus domesticus)
Br. Poult. Sci., 46 (2005), pp. 26-34