Abstract
BackgroundWelfare concerns, production losses caused by Dermanyssus gallinae, the poultry red mite (PRM), and widespread mite resistance to environmentally applied acaricides continue to drive an urgent need for new and effective control measures. Fluralaner is a novel systemic acaricide developed to address that need. A series of field studies was initiated to investigate the safety and efficacy of a fluralaner solution (10 mg/ml) administered in drinking water at a dose rate of 0.5 mg/kg on two occasions with a 7-day interval, for treatment of natural PRM infestations in chickens.MethodsBlinded, negative-controlled studies were completed in Europe across eight layer, two breeder, and two replacement chicken farms. At each farm, two similar flocks were housed in similar PRM-infested units (either rooms within a building, or separate buildings) varying from 550 to 100,000 birds per unit. One unit at each farm was allocated to fluralaner treatment, administered in drinking water on Days 0 and 7. One unit remained untreated. Mite traps were placed throughout each unit on Days -1, 0 or 1, 3, 6, 9, and 13 or 14, then at weekly or two-weekly intervals, retrieved after 24 h and processed for mite counts. Efficacy at each farm was assessed by mean PRM count reductions from traps in treated units compared with those from control units. Production parameters and safety were also monitored.ResultsEfficacy was 95.3 to 99.8% on Day 3 and 97.8 to 100% on Day 9, thereafter remaining above 90% for 56 to 238 days after treatment initiation. Post-treatment improvement in egg-laying rate was greater by 0.9 to 12.6% in the treated group at 9 of the 10 layer or breeder farms. There were no treatment-related adverse events.ConclusionFluralaner administered at 0.5 mg/kg via drinking water twice, 7 days apart, was well tolerated and highly efficacious against the PRM in naturally infested chickens representing a range of production types and management systems. The results indicate that this novel treatment has potential to be the cornerstone of an integrated approach to reducing or eliminating the welfare and productivity costs of this increasingly threatening pest.
Highlights
Welfare concerns, production losses caused by Dermanyssus gallinae, the poultry red mite (PRM), and widespread mite resistance to environmentally applied acaricides continue to drive an urgent need for new and effective control measures
At each farm fluralaner efficacy was determined by the reductions in mean mite counts from traps placed in houses containing only fluralaner-treated birds in comparison with counts from traps placed in houses holding untreated control birds
Mite count reduction On all sites, by Day 14 efficacy was greater than 99%, remaining at a level of at least 90% through the end of the production cycle; until mite regrowth in the treated unit, or until the study was terminated because of declining mite counts in the control unit (4 months, DC1) (Tables 3 and 4; Fig. 2)
Summary
Production losses caused by Dermanyssus gallinae, the poultry red mite (PRM), and widespread mite resistance to environmentally applied acaricides continue to drive an urgent need for new and effective control measures. Traditional methods have relied on a range of acaricides, including carbamates, organophosphates, amidines, pyrethroids, and more recently spinosad, applied to premises and/or birds as sprays, mists and dusts [11,12,13]. Limitations of these approaches include: difficulties of achieving miticidal levels in all the hard-to-reach sites that harbour mites; additional stress to the birds from pesticide applications; risks of residues and pesticide exposure of workers; and the emergence of resistance to the available acaricides [11,12,13,14,15,16,17]. There is a long-recognized need for novel methods of reducing or even eliminating the threats that arise from PRM infestations [14]
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