The poultry red mite, Dermanyssus gallinae, is currently the most economically important pest in poultry farming within Europe and has been discovered worldwide. However, D. gallinae resistance to acaricides, chemical withdrawal from poultry veterinarian product lists and the prohibition of conventional cage housing systems within some EU countries by 2012, means that alternative methods of control for this and similar ectoparasites are urgently needed. Considering that D. gallinae prevalence is generally higher in barn and free-range poultry systems compared to cages, it is becoming increasingly important to evaluate such alternative approaches to take into account future changes in housing in the poultry industry. One approach is to develop a vaccine against D. gallinae. Preliminary trials have shown that pathogens and symbionts within these mites can divert the immune response and that the humoral response of hens does not elicit protection from mite feeding. However, cellular responses and specific antigens such as "concealed antigens" may hold the key to D. gallinae neutralisation during its feeding. The interleukin IL-10 is significantly up-regulated in vaccinated birds compared to control groups, which may have repercussions upon immunosuppression. Further immunological work is now targeting improvement of the cellular response to limit predation by red mites. A second approach focuses on studying the repellent and toxic effects of some plant-derived products which can be used as natural "green" acaricides for managing D. gallinae populations in poultry housing systems. Preliminary work by Kim et al. (2004) tested 56 plant essential oils for their acaricidal effect on D. gallinae. Of these, oils from bay, cade, cinnamon, clove bud, coriander, horseradish, lime dis 5F, mustard, pennyroyal, pimento berry, spearmint and thyme all gave 100% mite mortality in contact toxicity tests at a concentration of 0.07 mg of oil per cm2. Further experiments by the authors showed that the acaricidal effect of selected oils was attributable to action in the vapour phase. Neem oil has also been tested against D. gallinae, with a 92% reduction in mite numbers in poultry houses fitted with traps containing 20% oil in water, as compared to houses that contained traps with water alone (Lundh et al., 2005). Finally, garlic oils and extracts appear to hold promise for poultry mite management, and products based upon garlic are already available commercially. Birrenkott et al. (2000) found that the application of ‘Garlic Barrier' reduced Ornithonyssus sylviarum (Northern fowl mite) incidence on treated hens in the US, and ‘Breck-a-Sol', a garlic-based acaricide advertised for use against D. gallinae, has recently been approved for use in the UK. A third approach is the use of entomopathogenic fungi. Application of conidia of different arthropod-specific fungi to D. gallinae has provided good results in laboratory studies, but still needs to be further explored under field conditions.
Dermanyssus gallinae, poultry pest management
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XVIII European Symposium on the Quality of Poultry Meat and XVII European Symposium on the Quality of Eggs and Egg products, 2007