Sampling methods to detect and estimate populations of Tyrophagus putrescentiae (Schrank) (Sarcoptiformes: Acaridae) infesting dry-cured hams

Abstract

Spatial and temporal dynamics of pest populations are an important aspect of effective pest management. However, absolute sampling of some pest populations such as the ham mite, Tyrophagus putrescentiae (Schrank) (Sarcoptiformes: Acaridae), a serious pest of dry-cured ham, can be difficult. In this study sampling methods were compared and sampling plans were developed for the ham mite. In one experiment, the number of food-baited traps was maintained at four and the number of mites varied from 500 to 10,000 individuals in environmentally-controlled 18-m2 rooms. The number of mites captured in traps increased linearly as the number of mites released increased. Experiments conducted in simulated ham aging rooms suggested that mites preferred the proximal (closer to the pig's body) to the distal side of the ham. The number of mites captured in traps also varied with trap location relative to hams hung from shelves. There were varying degrees of relationships between the number of mites captured in traps and the sampling methods used, such as counts of mites from the storage rack, vacuum sampling of the floor, and ham sampling. Relationships between absolute counts of mites and the number of mites captured in traps or on specific areas of ham were both moderately strong and significant. Two sampling plans were developed for the mite, and it was determined that an economic threshold close to 1 mite per sample unit on the ham can be estimated with 21 and 40 samples at precision levels of 0.35 and 0.25, respectively, or with 10 ham samples when classifying the mite's infestation level as being above or below an action threshold of 0.43. These sampling plans for the ham mite can facilitate the development and evaluation of cost-effective integrated pest management interventions.