10
May
Organic Farming Shown to Reduce Pesticide Load in Bird of Prey Species
(Beyond Pesticides, May 10, 2024) A study published by scientists in France from La Rochelle University’s Chizé Center for Biological Studies, in collaboration with the University of Strasbourg and the University of Burgundy, finds lower pesticide load in chicks from a bird of prey species in areas with organic farming. A correlation between lower numbers of pesticides in the blood of birds with the presence of organic farms surrounding the habitats was determined after analyzing 55 Montagu’s harrier (Circus pygargus) nestlings from 22 different nests in southwestern France. As the percentage of organic agriculture around the nests increased, there was a significant decrease in the quantity and types of pesticides detected within the chicks’ blood.Â
In beginning this study, the scientists hypothesized that “the application of organic farming practices is expected to reduce contamination levels in the environment and consequently in wildlife.†They also referenced studies, such as a soil study, that aided in this speculation: “In an analysis of topsoil samples collected across Europe, samples from organic farms showed significantly fewer pesticide residues and in lower concentrations than those from conventional farms … [with] 70 to 90% lower concentrations.â€Â Â
This study screened for 104 total compounds, 28 of which were detected in the blood of the Montagu’s harrier chicks. The chicks were evaluated during May-August of 2021 and their blood results contained 10 herbicides, 12 fungicides, 5 insecticides, and 1 synergist. The scientists then “used the number of pesticides detected and the total sum of concentrations of pesticides in chick blood as proxies of contamination levels.†As a result, “all chicks sampled (n = 55) were found to be contaminated with at least one pesticide, and the maximum number of pesticides detected per chick was 16.â€Â  Â
Some of the detected pesticides include bifenthrin, boscalid, clothianidin, cypermethrin, cyprodinil, difenoconazole, dimethomorph, epoxiconazole, indoxacarb, mecoprop, myclobutanil, oxadiazon, piperonyl butoxide, propyzamide, quinoxyfen, and thiacloprid. Each of these pesticides are linked to health effects in humans that range from skin irritation to cancer, endocrine disruption, neurotoxicity, kidney and liver damage, and birth, development, and reproductive impacts. Many of these pesticides are toxic to aquatic organisms, bees, and birds and have been banned in France. Their persistence in the environment is highlighted by their presence in the blood of the Montagu’s harrier chicks.              Â
Birds experience pesticide contamination in their blood through their environment, their food, and from maternal transfer–when pesticide compounds in the mother’s blood transfer to the fetus. As the scientists say, the Montagu’s harrier “eggs and chicks are directly exposed to local pesticide contamination throughout their growth period, through direct spraying on eggs, contact with contaminants remaining on the soil and on the crop, and through feeding on contaminated prey.†A key factor for this is the nest location in conjunction with the dietary exposure. The location not only affects direct contact with pesticides but determines the exposure levels within the available food sources in the surrounding environment.Â
The Montagu’s harrier species is a rare and declining bird of prey, similar to hawks and eagles, that summers in Europe/Asia and winters in Africa, choosing primarily to build nests in farmland. Their prey is comprised mostly of voles, small birds, shrews, rabbits, lizards, and insects that are found near their nesting sites, which they make on the ground. Studying birds of prey is a great indicator of the health of entire ecosystems, as impacts on the food chain from pesticide exposure can create an unwanted ripple effect. “Anthropogenic pollution associated with industrialisation, urbanization, and agricultural intensification has led to the contamination of multiple environmental compartments (i.e., biotic and abiotic elements), notably wildlife,†this study highlights. As more and more pesticides are developed to combat resistance and replace other pesticides that have been banned, a greater need arises for other alternatives that do not repeat the vicious cycle.Â
Female Montagu’s harriers bring small prey organisms like insects to the nestlings, while males will bring larger prey like voles from farther away from the nest. Their foraging area is according to prey availability, so this study “tested the effects of the proportion of organic farming at the scale of male’s home range†to assess the representative areas. This analysis shows a higher percentage of organic farming “significantly reduced the number of pesticides detected in chick’s blood†and that “a higher proportion of organic farming around nests significantly decreased the number of pesticides in Montagu’s harrier chicks both at the scale of the crop plot… and at a larger scale.†Â
Having a higher proportion of organic farming around nests not only decreased the total number of different pesticides in the nestlings, but it also reduced the different types of pesticides detected. In chicks that were primarily surrounded by organic farms, they generally had only herbicides detected in their blood. Nests that had fewer organic farms nearby often showed multiple pesticides from the herbicide, fungicide, and insecticide classes. This shows that “the lower number of compounds found in chicks from nests surrounded by higher proportions of organic farming at the field and larger scales, suggests that not only the direct environment of nests (soil and vegetation) is less contaminated but also that the prey hunted by parents in the close vicinity and brought to chicks is less contaminated.â€Â
In France, organic farming complies with the standards of legislation that bans synthetic pesticides and fertilizers to grow crops. “The present study reveals that organic farming reduces the number of pesticides in Montagu’s harrier chicks, which may have a beneficial effect on its population, as chemical inputs have been shown to drive farmland bird population decline across Europe,†the study authors postulate. Elimination of this species’ exposure to pesticide cocktails means elimination of exposure to all organisms within the food chain. As the scientists mention, “because the Montagu’s harrier is at the top of the trophic chain and a specialist predator species of agricultural lands, studying its contamination with pesticides is particularly relevant as an indicator of larger contamination of the environment.†Creating a more sustainable environment by addressing the issue of pesticide exposure allows for a cascade of positive effects on soil, water, air, and biodiversity.Â
Going organic or supporting organic are ways to promote change. Beyond Pesticides’ mission is to eliminate petrochemical pesticides and fertilizers by 2032 and the Beyond Pesticides website offers many resources to assist in this transition. View Protecting Biodiversity with Organic Practices to learn how organic agriculture protects species richness. Keeping Organics Strong provides updates on organic regulations and opportunities to take action. Subscribe to the Daily News for articles on the effects of pesticides and benefits of organic practices.Â
 All unattributed positions and opinions in this piece are those of Beyond Pesticides. Â
 Source:Â
Fuentes, E. et al. (2024) Organic farming reduces pesticide load in a bird of prey, Science of The Total Environment. Available at: https://www.sciencedirect.com/science/article/pii/S0048969724029255.Â
