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Improved estimation of pesticide residues on arthropods consumed by mammals and birds – validation of semi-field data - PS2323

The current approach (under Council Directive 91/414 EEC according to the EU Guidance document for bird and mammal risk assessment (SANCO/4145/2002)) to assessing the pesticide residues on invertebrates consumed by birds and mammals is based on comparison of small and large insects with seeds and pods. The guidance document also states there is an urgent need for data to support the use of invertebrate residues in vertebrate risk assessment. The original data set upon which this information was based has been updated and remodelled to provide more accurate initial estimates of exposure for insectivorous birds and mammals (PN0935). This has shown that assumptions underlying the derived estimates may not be valid and there is an urgent need to develop more soundly based estimates for residues on invertebrates. CSL has been collaborating with the agrochemical industry to develop data suitable to address the current needs of risk assessment for insectivorous birds and mammals in a range of crops. A pilot study (PS2311) identified some suitable arthropod species and provided a limited data set to suggest a suitable way forward. This project will provide further data to support such an approach in cereals and broad-leafed crops. Industry representatives are funding field studies to determine invertebrate residues in other crops and together the data should provide a robust approach to revising the risk assessment methodology for insectivorous birds and mammals.
A suitable worst-case approach at the first tier risk assessment would be to assume intake only of the invertebrate food item shown to have the highest residues (e.g. aphids for cereals, lepidopteran larvae for broad-leafed crops). At higher tiers of the risk assessment residues on a wider range of species found in the crop may be combined with data on the composition of the diet of the indicator species to estimate intake from a more realistic mixed diet. However, although this appears a pragmatic approach, the range of compounds used in the pilot study was limited (one fungicide and one insecticide) and only one formulation type was tested (formulation types may affect uptake, e.g. WP vs EC). There is therefore a need to expand both the range of chemicals and range of formulations studies to ensure the concept is valid and suitable RUDs are selected. The data also showed a difference in the uptake of residues between leaf dwelling species and leaf consuming species. Although the residues declined significantly over time in both aphids and syrphids the residues in the caterpillar Pieris brassicae did not. The residues in leaf consuming species may be expected to relate to the half-life of the pesticide in the plant, therefore, there is a need to compare the DT50 in plants and invertebrates to assess whether such an approach is appropriate. The data also suggested that the most appropriate approach for ground dwelling beetles, consumed by birds such as robins and blackbirds feeding on ground dwelling species around crops, may be to use overspray residues on live invertebrates and use interception factors such as those factors developed for the FOCUS groundwater scenarios.
The further development of these data and the development of guidelines for assessment of residues on invertebrates in cereals and broad-leafed crops following field applications, alongside industry-funded studies on orchards and vineyards should provide the basis of a more robust/realistic assessment of the residues on invertebrates and exposure of birds and mammals based on those that prey on crop-dwelling and ground-dwelling invertebrates.
This study aims to further develop the data generated in the pilot study with the intention, ultimately, of allowing it to be used in first and second tier risk assessment for insectivorous birds and mammals by:
1. Developing the limited data set further to give confidence in the data for a wider range of active ingredients and formulations.
2. Conducting limited field validation of the data using plots in cereals and broad-leafed crops to provide confidence that the data are not over-protective of the real environment.
3. Validating the use of overspray with the use of interception factors for ground dwelling beetles.
4. Developing guidelines for assessment of residues on invertebrates in cereals and broad-leafed crops following field applications.
Project Documents
• Final Report : Improved estimation of pesticide residues on arthropods consumed by mammals and birds – validation of semi-field data   (99k)
Time-Scale and Cost
From: 2005

To: 2007

Cost: £152,851
Contractor / Funded Organisations
Central Science Laboratory
Pest and Weed Control              
Pesticide Residues              
Pesticide use              
Plants and Animals              
Fields of Study
Pesticide Safety