§ Dr. Roger Thomasasked the Minister of Agriculture, Fisheries and Food if he will make a statement as to the possible potential deterioration in the efficacy of synthetic pyrethroids, that could result in the worsening of hygiene conditions in the agriculture and horticulture industries.
§ Mr. WigginSynthetic pyrethroids are no exception to the general rule that insecticides can lose efficacy where resistance develops among the target species concerned. This is liable to happen where products are used extensively and regularly. So far resistance to synthetic pyrethroids has not been established in any outdoor British pests; but it has been found in some indoor pests including the flour beetle, the glasshouse white fly, the grain weevil and the housefly. In the case of houseflies such resistance could pose hygiene problems in intensive livestock enterprises, but there are already alternative forms of control and others are being explored.