Title page for ETD etd-07082010-020150
|Type of Document
||Hall, Robert Dickinson
||Adrenal steroid, blocking agent, and social stress effects on northern fowl mite population development on Leghorn chickens and toxicological evaluation of selected acaricides (Acarina: macronyssidae).
|Turner, E. Craig Jr.
|Grayson, James McD.
|Gross, W. B.
|Robinson, William H.
|Date of Defense
Administration of adrenal steroids or blocking agents at optimum
doses influenced northern fowl mite development on chickens. Corticosterone
at 20 ppm or desoxycorticosterone at 30 ppm in feed were most effective
in inhibiting mite infestations. High levels of social stress
increased resistance of chickens to mites in a manner similar to but
more effective than steroid administration. The mechanism of resistance
was a decrease in capillary density at the skin surface. Commercial
laying hens caged alone had lower plasma corticosterone levels and supported
more mites than hens caged in groups. Stress-induced, steroid
initiated, or inbred mite resistance was incompatible with maximum production
from chickens. Resistant chickens produced poorer weight gains
and testes mass than did susceptible birds. Sex hormones were shown to
play a supplementary, and antibody a minor role in mite resistance.
Carbaryl was shown to be the compound most toxic to northern fowl
mites of those registered in Virginia for application to poultry. Malathien
resistance was noted in mites from a commercial poultry house.
The synthetic pyrethroid permethrin was effective against these mites.
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