27 



The mode of action of pyrethroid poisoning is fairly complex. 

 Initial signs in insects are usually incoordination and locomotor 

 instability which are collectively termed knockdown. Details can be 

 found in Wouters and van den Bercken (1978). 



Resistance to pyrethroids can be detected in house flies after 

 several months of strong selection pressure (Keiding, 1976). Permethrin 

 resistance has been reported in culicids (Priester and Georghiou, 1978), 

 and cross-resistance has been reported in DDT-res i stant strains of 

 culicids (Prasitt'suk and Busvine, 1977) and cattle ticks, Boophilus 

 micvoplus (Nolan et al., 1977). 



Shono et al. (1978) reported that metabolic detoxification by 

 ester hydrolysis and hydroxylat ion is a major factor iimiting the 

 insecticidal activity of the permethrin isomers. 



Northern Fowl Mites_ 

 Description and Biology 

 Economic importance 



The northern fowl mite is considered to be the most serious ecto- 

 parasite of poultry in the state of Florida (L. W. Kalch, personal 

 communication), as well as the U.S. (Sulzberger and Kaminstein, 1936; 

 Miller and Price, 1977; Smith, 1978). Since it was first recognized as 

 a poultry pest by Wood in !920, the northern fowl mite continued to 

 spread across the country with increasing incidence (Linkfield and 

 Ried, 1953). 



Lyon (>975) stated that in 1970, the northern fowl mite could be 

 costing the poultry industry $80 mi 1 ! ion annually. Smith (1978) quoted 

 DeVaney as estimating an annual $66 mil 'ion loss due to external 



