A small pest causing big problems in flocks of all sizes – Agriland

Poultry red mites (Dermanyssus gallinae) are the most significant mite threat throughout Europe and affect the smallest of backyard flocks to the largest commercial production units.

This tiny mite also has a significant impact. Recent surveys estimate the total annual cost of infestations in the European egg laying industry to be 232 million, affecting more than 390 million hens in all production types: breeders; pullets; and layer hens.

Red mites live and rapidly breed within the hen house and the surrounding areas but only emerge at night to crawl onto and suck blood from the birds, before retreating to cracks and crevices during the day.

They are able to survive and reproduce at a wide range of temperatures, but it is during periods of warmer weather that populations increase rapidly. One female mite, and her descendants, can produce 2,000 more mites in a month.

We have had a warmer than average April in Ireland this year, explained Maureen Prendergast, poultry technical manager at MSD Animal Health. And, as a result, were already hearing reports of increased levels of poultry red mite in some commercial units.

Small numbers of mites may be tolerated by laying hens but, when a critical threshold is exceeded, mite infestation results in reduced productivity due to anaemia, decreased egg production and quality, reduced growth of birds and increased mortality from stress and the presence of other diseases.

Mites are known to carry a multitude of viral and bacterial pathogens and the presence of these in birds that are compromised from mite infection results in higher levels of mortality.

Even at low levels, mites may cause pecking among birds resulting in injury, warned Maureen.

This adds to the welfare significance of infestation with red mites. Of course, mites can also affect the humans looking after the hens, causing irritation and scratching and even an allergic dermatitis in some susceptible individuals.

Biosecurity alone is often insufficient to control their spread as they are carried by wild birds, rats and other mammals, the boots of farmers or in feed. They can also make their way at great speed through very small cracks and gaps and for long distances.

Poultry keepers should be on the lookout for signs of mite infestation early this season. In very heavy infestations, mites will be seen in greyish clumps with their eggs under the perches or in dark corners of the shed.

The most useful way to check the levels of mites in a commercial laying unit is to set traps in strategic routes for the mites as they climb to the perches. Smallholders, or those with backyard flocks, may notice their hens are reluctant to return to the hen house at night or seem noisy and unsettled, advised Maureen.

Current management methods lack sufficient effectiveness to keep mite infestations under control at many poultry farms, and often pose safety threats for both birds and humans.

The issue of residues in eggs and poultry meat has become more significant due to the enforcement of the EU directive on Biocidal Product Regulation 528/2012 which controls poultry disinfectants and mite powders.

A novel licensed product, containing fluralaner, has been available for the destruction of poultry red mites since 2017, with over 7 million hens treated in the island of Ireland.

Treatment consists of two applications (via the drinking water), seven days apart in order to target all stages of the life cycle. Previously only available to professional poultry farmers, it is now available for smaller flocks. The egg withdrawal period is zero days.

For information and advice on the threat of poultry red mite and the best control strategy for your farm, contact your veterinary practitioner or MSD Animal Health, Red Oak North, South County Business Park, Leopardstown, Dublin 18, Ireland.

MSD Animal Health can be contacted at: 01-2970220; or emailed at: [emailprotected].

Sponsored by MSD Animal Health

Visit link:
A small pest causing big problems in flocks of all sizes - Agriland