Integrated pest control in forest management — Combined use of pheromones and insecticides for attracting and killing the Bark Beetle Ips typographus I. Studies with 32P-labelled methamidophos in the ascending sap of spruce

In 1984–1986, ³²P-labelled methamidophos was used to investigate the translocation, distribution and breakdown of this systemic insecticide after penetration into the ascending sap of spruce (Picea abies Karst.), following bark treatment with an adhesive paste of 15% active ingredient. The β-radiation of ³²P permits a semi-quantitative measurement on the bark of standing trees as well as quantitative sample analysis and autoradiography. The following results are given: method of application and total ³²P in the ascending sap; distribution of ³²P in trunk cross-sections and in bark/needles; ³²P in the killed beetles corresponding to the toxic dose, separation of methamidophos and breakdown products; halflife of breakdown in vitro and in vivo; and environmental implications. From the xylem, methamidophos penetrates into the phloem, but no ³²P appears outside on the surface of the bark, so that only insects mining inside the bark are killed and no hazards for useful insects, birds and wildlife animals can arise. Traces of ³²P were measured in air and water, and no ³²P was found in the soil due to the translocation upwards only. The approximate oral toxicity of methamidophos to Ips typographus was estimated to be < 5 mg/kg and the half-life in spruce was 45 days (15°C), indicating a sufficient biological effectiveness over several months, preferably in areas of low average temperatures and in trees impaired by environmental pollution.