Possible correlation between residues in concentrates and number of insects and meadow birds investigated

Feed, manure, insects and meadow birds There is still a lack of knowledge about the spread of plant protection product residues in the feed on a dairy farm with a possible effect on the meadow birds’ food.

From cow feed to meadow bird
Cows generally eat roughage (grass / corn) from their own farm and concentrates (cereals / legumes), which are often imported and processed. In the cultivation of this concentrate, plant protection products are used all over the world to prevent and control diseases, pests and weeds. In addition, disinfectants and pesticides are used during transport and storage, for example to prevent insect damage. Ultimately, the residues (residues) of these agents can via golden end in the meadow, in the middle of the meadow bird’s habitat. There they can affect the number of exactly desired insects; insects that, among other things, are food for meadow birds and their young.

The task
A possible link between residues and the number of meadow birds was first addressed in a report by Buijs and Samwel-Mantingh (2019). Parliamentary questions have been asked in this regard. Following the report and a submitted proposal, the Ministry of LNV has given the Louis Bolk Institute the task of mapping the possible distribution routes for plant protection products via concentrates and their consequences; how do these resources end up on the pasture? The possible effects on insects as food for meadow birds are also important. The purpose was to indicate what is known, but also where knowledge is lacking and what research is still lacking.

The route for plant protection products
A schedule has been prepared with the different steps from plant protection products via feed to the soil and to insects that depend on it. These steps range from growing the concentrate’s raw materials for storage and transport, processing into concentrates, uptake / digestion in the cow and to manure. In all these steps, plant protection products can change character and effect. The next step of spreading manure in the soil and the possible effects on soil life were also discussed (in the research report); soil life that is directly or indirectly dependent on this fertilizer as food. The last step is the food supply for meadow birds in the form of earth life (eg earthworms) and manure-dependent insects (eg manure beetles).

Conclusions: very lack of knowledge, little public information and precautions
The conclusion is that there are residues of chemical (plant protection) agents in the concentrate, but that there is (too) little publicly available information about their content and variety. It is also clear that there are residues in the cattle manure and thus eventually end up on the ground, but that here too there is a lack of public information about levels in the manure and its distribution. International research suggests that high levels of residues in manure or soil can have major effects on insect survival. But the real effect for the Netherlands can only become clear with more public insight into the actual content of specific substances in concentrates and fertilizers. Therefore, there is no certainty about the effects on the food availability of the meadow birds. However, some residues are known to have a strong influence on insects; a precautionary principle would be advisable here.

Further research
The Louis Bolk Institute proposes a research agenda in which residues of plant protection products in concentrates, raw materials and manure are measured and the level of risk in the environment is calculated. Other aspects to be investigated are the effect of residues on soil life and the development of guidelines for safe concentrations in manure. Prioritization of the specific group of ‘insecticides’ is obvious due to the most direct effect on the survival of precisely desired insects in the meadow.

Minister Staghouwer from LNV presented the research report to the House of Representatives and asked in response to the results RIVM to conduct a probing study of the level of residues of plant protection products in cow peas in the meadow, to see to what extent risky levels occur. Against this background, further empirical research into the other identified knowledge gaps may follow. The Louis Bolk Institute will follow the research results with interest.

Click here to read the research report.

For more information:
Louis Bolk Institute
Kosterijland 3-5
3981 AJ Bunnik
+31 (0) 343 523 860

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