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RELATION OF MITE INDEX TO <br /> Figure 1. NUMBER OF HENS INFESTED <br /> ,00 <br /> 75 .. . <br /> N <br /> C 50 "_... .:..... <br /> o a <br /> • � A Y=7.16 + 35.55X R2=0.876 <br /> 25 .'_. . . ._..._ -- <br /> „00 •0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2 2.2 2.4 2.6 <br /> Avg. Mite Index <br /> the eggs and worker complaints are This leaves us with two questions: Where <br /> indications of a relatively severe do we look for mites, and do we need to <br /> infestation. Using the appearance of treat the entire house? <br /> mites on the eggs as an indicator of a mite <br /> problem in the house may not be sensitive No differences in infestation level were <br /> enough to allow effective control. Figure observed along the length of the house; <br /> 1 suggests that if control measures are to however, significant differences between <br /> be employed before 100 percent of the rows were observed. These results suggest <br /> hens are infested, the inspector will need that for this type of house, it would be <br /> to be able to detect mites at populations important to sample every row for mites; <br /> in the order of 10 to 50 per bird. This will and that it wouldn't matter whether the <br /> obviously require training and patience. sample came from the middle or either <br /> end of the house. <br /> The distribution of mites within a poultry <br /> house is likely to be uneven. Several How many birds do we need to evaluate <br /> things can cause this. If pullets are to make a decision whether or not to <br /> infested when they are placed, usually not apply a pesticide treatment? There are <br /> all of the birds will have mites. If the several methods of statistical sampling that <br /> infestation is a result of wild birds, the will provide us with the necessary <br /> shedding of the mites will probably not be information to make an informed decision. <br /> uniform throughout. As mentioned above, Some of these methods require larger <br /> mites prefer some temperatures to others, sample sizes than others, however. <br /> and so microclimates within the house Sample size is not only an important <br /> could contribute to pockets of infestation statistical consideration, but is also an <br /> 3 <br /> f <br /> h� <br /> 3L,' <br />