22 September 2017 | Online since 2003

24 March 2017

Housing order causes surge in red mite


The red mite population has "exploded" since the housing order was introduced.

The housing order introduced to try to prevent the spread of avian influenza has resulted in a surge in the numbers of red mite in layer flocks.

St David's Poultry Team, a poultry veterinary specialist based in Devon but with offices around the country, says the red mite population has "exploded" since the housing order was introduced across the United Kingdom in early December.

The Government has now lifted the housing order across most of the United Kingdom, although farmers are still required to house their birds in designated higher risk areas.

"We have been very happy with the results. Dergall works in a unique way."



However, vets have seen increased incidence of red mite infestation on layer units.

'Increase in red mites'

“With the birds being shut in for the past few months we have had a number of calls and visits where we have seen an increase in red mites in layer housing, which is something at this particular time of year and certainly from January until now you don't normally see such high levels," said Alison Colville-Hyde, field services manager at St David’s Poultry Team.

“It's something that some of the vets are a little concerned about for spread of disease and also for drop in egg production. Red mite control is something that's quite at the forefront of what we are seeing in practice at the moment."

She said: “Red mites aren't just a problem to the birds in that they suck their blood and they cause them a lot of distress and stress, and potentially anaemia and death. They can actually spread diseases such as mycoplasma, salmonella, coccidiosis and various other things as well.

“When they bite they are actually puncturing through the skin and that infection can go straight into the blood stream. If that happens and you have a multi-age flock, for example - multi-age site with flocks of different ages - you've potentially got that continual risk of red mites spreading disease on your site," said Alison.

Sucking blood

Red mites feed on birds at night, under the cover of darkness, by sucking their blood.

Once they have fed, the mites crawl back out of sight into hard-to-reach places of the poultry house, often never seen until the infestation is out of control. “Mite infestations can cause huge stress on the birds," said Alison.

“Initially you may not realise the mites are present but, as their population develops, the hens become agitated, often hardly resting during the night, which is an important time for them to relax and recharge ready for the next day’s feeding and egg laying.”

She said: “Red mites can carry disease from one flock to the next and, in heavy infestations, they suck so much blood from the bird they can cause anaemia and eventually death. Egg production can dip and red streaks on the eggs, caused by the mites, may be seen too.”

She said: “Red mite can be debilitating to hens and irritating to egg collectors, as well as causing economic loss through egg downgrades and increasing the risk of disease transfer.”

New treatment

Alison said that a new treatment developed in Poland was now available for dealing with red mite and was proving very effective.

She said the product, called Dergall, had been developed by a company called ICB Pharma, which had taken principles used to deal with aphids and applied them to red mite. She said the product was non-toxic and, unlike existing products, it worked mechanically.

“We got to hear about it a few months ago - a new product called Dergall, which has been created by a pesticide company in Poland called ICB Pharma. We got in touch with them and they have spoken to us about it. We trialled the product before we committed to it. We have trialled it on a colony cage unit and on a free range unit and we have another free range unit under trial at the moment," she said.

“We have been very happy with the results. It works in a unique way. That's what's special about it. Dergall actually works in a mechanical way. It's not actually systemically going into the red mite like so many other so-called insecticidal treatments.

“It's totally mechanical so you don't get the issue of resistance. It's not toxic, so it doesn't cause the birds a potential risk, operatives or the eggs. So it's a food safe product. It's quite exciting from that point of view.

“In a nutshell, how it works is, once it's activated with water and it's sprayed onto a surface such as slats or nest boxes, perches or any equipment in the house, it very quickly starts to form at microscopic level a little mesh area which causes the red mite to be entrapped within it. Within a few hours those red mites will die."

She said: "There's nothing else on the market at the moment doing that sort of effective control without being toxic."

Strict measures

Although the housing order has now been lifted in most of the country, strict measures remain in force to try to control the spread of avian influenza.

The highly pathogenic strand of avian flue, H5N8, has spread across most of Europe this winter, with at least 10 cases confirmed in the United Kingdom, although none have been on layer units.

Egg producers are being urged to maintain strict bio-security against disease. Alison said that, because red mites could carry disease, they had to be dealt with to maintain good bio-security. "Picking the right treatment is key," said Alison.

She said, "It's really down to the owner of the birds and managers as to how they wish to deal with that. I think when the problem gets out of hand and they see that their production is dropping so much then they might get the vet involved. They are really giving out bespoke advice according to what they are seeing on those sites."

She said that St David's Poultry Team had been making use of Dergall, which had taken four years to develop, for the last month.

"It is very new to the market - so new that the company is still working on the English labelling." However, she said that St David's had been impressed with the results they had been achieving.

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