Presence-Absence Sequential Sampling Plan for Northern Fowl Mite, Ornithonyssus sylviarum (Acari: Macronyssidae), on Caged-layer Hens

• Published in: Journal of economic entomology 2000-04, Vol.93 (2), p.544-549
• Main Authors: Harris, Mary A., Brewer, Michael J., Meyer, Jeffery A.
• Format: Article
• Language: English
• Subjects: Animals; Biological and medical sciences; Chickens - parasitology; Fundamental and applied biological sciences. Psychology; Medically important nuisances and vectors, pests of stored products and materials: population survey and control; Mite Infestations - parasitology; Mite Infestations - therapy; Mite Infestations - veterinary; Mites; Nuisances; Poultry Diseases - parasitology; Poultry Diseases - therapy; VETERINARY ENTOMOLOGY
• ISSN: 0022-0493; 1938-291X
• DOI: 10.1603/0022-0493-93.2.544

Caged-layer hens were scored as infested or uninfested by visual examination of the vent region, and the number of northern fowl mite, Ornithonyssus sylviarum (Canestrini & Fanzago), per hen was estimated. The proportion infested and average number of mites per hen were shown to have a highly significant, positive relationship (r = 0.936). Sampling among houses within a flock, and rows and sections within houses were analyzed to determine the reliability of sampling a representative portion of a flock. Low- and moderate-tolerance treatment thresholds, based on percentage of hens infested with mites, were developed from sampling 1 wk before and 1 wk after acaricide treatments determined necessary by the producer. These thresholds were used to compare a fixed (single) sampling plan, a curtailed procedure of the fixed sampling plan, and a sequential sampling plan based on a sequential probability ratio test, by sampling 174 hens (the maximum number needed for the single sampling plan). The sequential sampling plan required fewer hen examinations on average to reach a treatment decision than did the other plans, depending on the infestation tolerance limits. Using a low tolerance approach in which infestations below 15% are considered noneconomic (safe threshold) and infestations above 25% are considered economically important (action threshold), as few as 5 hens required examination to reach a treatment decision. Sequential sampling plan graphs are presented for 2 tolerance threshold scenarios (a 15% safe-threshold paired with a 25% action threshold and a 35% safe-threshold paired with a 45% action threshold). These sequential sampling plans using presence absence assessments should greatly facilitate monitoring and treatment decisions for this important pest.