Pesticide use and residues on Queensland wool.
OBJECTIVE
To determine practices for control of louse infestation and blowfly strike in Queensland sheep flocks that are associated with organophosphorous and synthetic pyrethroid residues on wool.


METHODS
Information on residues was obtained from a survey of Queensland wool clips. Information on pesticide use was obtained from a trace-back postal survey. The association between pesticide use and residues was assessed using generalised linear models, controlling for potential confounding by flock location.


METHODS
Between 1995 and 1997 Queensland wool clips were randomly sampled. Samples were tested for the presence and amount (mg per kg of greasy wool) of organophosphorous and synthetic pyrethroid pesticides. A questionnaire seeking information on flock characteristics and pesticide use was sent to the manager of each flock from which a wool sample was tested.


RESULTS
The median amount of OP and SP residue was 0.8 and 0.25 mg/kg, respectively, and 91 and 95% of wool samples contained < 8 mg/kg of OP and SP residues, respectively. The frequency of OP pesticide use for louse control was significantly (P = 0.005) associated with mean OP residue amount, and the timing of SP use for louse control, in relation to shearing, was significantly (P < 0.001) associated with mean SP residue amount.


CONCLUSIONS
Most Queensland wool clips have acceptable amounts of residues after the use of OP and SP pesticides, but wool growers can further reduce residues by effectively controlling louse infestation with pesticide applications early after shearing and the use of non-chemical methods of ectoparasite control.
Ward
M P
MP
Queensland Department of Primary Industries, Animal Research Institute, Moorooka, Queensland.
Armstrong
R T
RT
D000818:Animals; D004478:Ectoparasitic Infestations / Q000517:prevention & control / Q000662:veterinary; D007306:Insecticides / Q000032:analysis* / Q000138:chemical synthesis / Q000627:therapeutic use; D016014:Linear Models; D009943:Organophosphorus Compounds; D010573:Pesticide Residues / Q000032:analysis*; D011722:Pyrethrins / Q000032:analysis* / Q000138:chemical synthesis / Q000627:therapeutic use; D011793:Queensland; D012756:Sheep; D012757:Sheep Diseases / Q000473:pathology; D011795:Surveys and Questionnaires; D014935:Wool / Q000737:chemistry*
D007306:Insecticides; D009943:Organophosphorus Compounds; D010573:Pesticide Residues; D011722:Pyrethrins