Hen housing (cage or cage-free) did not impact overall abundances of northern fowl mites, Ornithonyssus sylviarum (Canestrini & Fanzago) (Acari: Macronyssidae), or chicken body lice, Menacanthus stramineus (Nitzsch) (Phthiraptera: Menoponidae). Cage-free hens received a dustbox with sand plus diatomaceous earth (DE), kaolin clay or sulphur. Weekly use varied from none to 100% of hens; 73% of hens used the dustbox at least once. Ectoparasite populations on dustbathing hens (users) were compared with those on non-user cage-free and caged hens. All materials reduced ectoparasites on user hens by 80-100% after 1 week of dustbox use. Diatomaceous earth and kaolin failed to reduce ectoparasites on non-user hens, and ectoparasites on user hens recovered after dustbox removal. A sulphur dustbox eliminated mites from all hens (including non-users) within 2-4 weeks. Residual sulphur controlled mites until the end of the experiment (up to 9 weeks), even after the dustbox was removed. Louse populations on hens using the sulphur dustbox were reduced in 1-2 weeks. Residual sulphur effects were less evident in lice, but the use of a sulphur dustbox by a higher proportion of hens extended louse control to all hens. This is the first experimental study to show that bird dustbathing in naturally and widely available dust materials (particularly kaolin) can suppress ectoparasites and thus the behaviour is probably adaptive.

The northern fowl mite (NFM), Ornithonyssus sylviarum (Canestrini and Fanzago), is the most widespread and damaging poultry ectoparasite in the United States [1,2]. The mites live in the vent feathers of hens, are obligate blood feeders as protonymphs and adults, and complete a life cycle in 5 to 12 d [3]. Mite infestations, in addition to being a nuisance for human workers and egg handlers, cause reductions in egg production, feed conversion efficiency, and BW gains and may affect egg size as well [4]. A key mechanism of damage is that NFM force the immune systems of hens to engage the mite infestation, and this metabolic cost diverts resources that might otherwise be devoted to normal body functions, including egg production [4].Mite control is currently based on exclusion or biosecurity [5] and pesticide applications. Resistance is high to the few remaining traditional registered materials [6], so producers are actually in a rather precarious position regard- SUMMARYLiquid formulations of nontraditional materials for northern fowl mite control were applied to the vent feathers of infested hens, and the mite populations on hens were monitored before and after treatment. High concentrations (≥5.3%) of sulfur eliminated mites for periods of at least 8 to 10 wk. A lower sulfur concentration (0.9%) essentially eliminated mites for approximately 4 to 5 wk and greatly reduced mites for 5 to 8 wk. Azadirachtin (derived from the neem tree) at 0.06% reduced, but did not eliminate, mites for approximately 3.5 wk after treatment. Of the inert dusts, kaolin (12% by wt, in water) somewhat reduced mites for approximately 1 wk after 1 application, but 2 consecutive weekly applications controlled mites for 2 to 3 wk. Diatomaceous earth (12% by wt, in water) reduced mites significantly only if applied for 2 consecutive weeks, and its effects then lasted <2 wk. Beauveria bassiana at 1 × 10 8 conidia/mL effectively killed mites in a glass tube, but showed only moderate on-hen control for 1 wk in 1 of 2 trials. In declining order of effectiveness, the materials were ranked as follows: high sulfur > low sulfur > neem > kaolin clay > diatomaceous earth > Beauveria.

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