Experiments on the Possible Contamination of Honey With Schradan

The reported low toxicity of schradan to honey‐bees has been confirmed. This has led to the consideration of the possibility that this systemic insecticide might be present in nectar and subsequently appear in honey in an unchanged form. Using radioactive schradan labelled with 32P, it has been shown that spray applications of this insecticide to mustard and borage plants result in the contamination of nectar. A series of nectar samples taken over a 4‐week period following spraying showed on radio assay a progressive decrease in total 32P content and also in the amount of schradan present in proportion to the decomposition products. The highest figure recorded for the schradan content of nectar was 21 p.p.m. Tests on the stability of schradan in contact with the honey stomach of the bee and also in contact with the enzyme invertase, in vitro, showed that no appreciable breakdown occurred. Furthermore it was shown that schradan was stable in contact with honey over a period of 2 1/2 months. It is concluded that this systemic insecticide may appear in an unchanged form in the honey obtained from the nectar of plants which have been sprayed less than 4 weeks previously.