Northern fowl mites (Ornithonyssus sylviarum) are the most common and economically important ectoparasites in US laying hen flocks. Mites are permanent ectoparasites and cause damage to birds via blood feeding. Once in a flock, they can be very difficult to eradicate from a property. Mite control has traditionally relied on chemical sprays directed at high pressure underneath the birds and into the vent region where mites live; these applications are most effective when birds are held in battery cages. However in recent years animal welfare concerns and consumer demand has affected how laying hens are housed. The transition to furnished-cage or cage-free production systems will require novel control techniques to achieve ectoparasite control. I investigated possibilities for ectoparasite control that would be effective in alternative poultry housing.

Breeding for parasite resistance is an attractive control method. Chickens develop resistance to the northern fowl mite (NFM) and this is under at least some genetic control. I tested whether the haplotype conferring NFM resistance had any effect on chicken resting metabolism (energy expenditure), physiology, or economic performance. Bird haplotype did not affect hen metabolism or production parameters. NFM infestations negatively affected economic performance.

Dustboxes have been shown to effectively decrease mite populations in cage-free flock when insecticidal dusts are used in combination with sand. I tested whether dustboxes with sand and diatomaceous earth could keep mites below economic thresholds before mite levels became damaging. When dustboxes were present in a flock, mite levels were on average kept below economic threshold regardless of percent of the flock that dustbathed.

Sulfur dust is effective for NFM control in very low doses, though it is not universally approved for organic use. I tested whether sulfur deployed in a dust bag would be effective in caged (non-organic) flocks and if the placement of the bag affected efficacy. Hanging dust bags offered the best NFM control.

Backyard chicken flocks are a growing trend in this country, and nothing is currently know about ectoparasite diversity on these birds. I surveyed 100 birds on 20 properties in southern California. Greater diversity was found on backyard flocks than on commercial birds.

Chaetodactylidae mites are kleptoparasites of solitary bees in the families Megachilidae and Apidea. Chaetodactylus krombeini is a North American pest most often associated with Osmia lignaria. Chaetodactylidae mites can cause up to 50% losses of bee offspring in nests and cause adult bees to develop into less efficient pollinators. Managed Osmia beekeepers need control methods for these parasites, however there is little known about C. krombeini life history making it difficult to efficiently decrease their harmful effects. Mite host preference is unclear as there are contradictory reports of male and female bees being the preferred host of the phoretic deutonymph. Host sex preference was examined by recording mite distribution within host nests. Mite distribution determined if phoretic deutonymphs dropped off hosts in female cells (back of nest) or male cells (middle and near nest entrance) during nest building. This experiment yielded low mite numbers within each nest, though mites were found in the back of nests regardless of host sex, possibly indicating mites have a positional preference rather than a host sex preference. Heteromorphic deutonymphs of C. krombeini are hypothesized to be exclusively female. This hypothesis leads to additional hypotheses of C. krombeini requiring arrhenotokous parthenogenesis and oedipal mating to found mite populations. Sex determination assays of the heteromorphic deutonymphs were conducted in 2-week periods for each mite. Inert and phoretic deutonymphs were individually placed in microcentrifuge tubes with a pollen provision then sexed when mites developed into adults. Phoretic deutonymphs were allowed to overwinter with and without a bee host. Males and females developed from both morphs of the heteromorphic deutonymph. Male and female dispersal prior to mating may indicate sexual reproduction is required for this species. Scanning electron microscopy was used to examine C. krombeini morphology to gain insight into life history traits. Specimens of C. krombeini were prepared with ethanol and hexamethyldisilazane. Images will be useful to compare the morphology of C. krombeini to mites with known life history traits and to other species that are indistinguishable from C. krombeini. These experiments contribute to the knowledge of C. krombeini, helping future control efforts of this pest.

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