April 20, 2024

Is organic food good for health? Maybe, but it affects flying mammals

Organic food without pesticides, hormones, fertilizers, herbicides, antibiotics, artificial chemicals, and genetically modified organisms is considered by many to be better for human health and better for biodiversity than conventional farming.

But bat activity declines as farms make the transition to organic agriculture, according to new research into insect-eating bats at citrus orchards in Cyprus, according to a new study led by the Universities of Bristol, Göttingen, and Exeter.

The paper, published in the Journal of Applied Ecology, was titled: “The shift to organic farming has a negative impact on bat activity.”

The effectiveness of organic farming on biodiversity has been widely documented, particularly for plants, arthropods and birds; However, the effects of the transition required to become an organic farm on wildlife are still not well understood.

Agriculture is a major use of land throughout the world and especially in the enlarged European Union, which comprises 45% of the land cover and involves a lot of intensive agriculture. The biological simplification of the farming environment is a direct result of the intensification and expansion of modern agricultural practices over the past century, becoming increasingly visible through the decline of farmland biodiversity and the reduction of compositional and configurational landscape heterogeneity.

A traditional citrus orchard in Cyprus. (credit: Penelope Fialas)

Organic farming may harm bats

The study examined 22 matched pairs of citrus orchards, comparing bat activity on certified organic farms to conventional farms, and organic transition farms to conventional farms. The bat species included in the study were the Kuhl’s shrimp, the Savi shrimp, the common bentwing), and the common shrimp.

The activity of three of the four species included in the study was much lower on farms in the transition period, compared to normal farms. However, there was an increase in activity on established organic farms – suggesting that there is a “lag time” before increasing organic biodiversity for the most abundant bat species.

“Our results surprised us; we expected the transition to organic farming to have positive effects from the start,” said Penelope Fialas, from the University of Exeter.

“We can’t be sure why bats are adversely affected, but previous research suggests that soil may suffer – with knock-on effects on other wildlife – when fertilisers, pesticides and other aspects of conventional farming stop. “It may take time for the soil and the wider ecosystem to recover.”

Fialas added that “our results suggest that the transition to organic farming should be carefully managed, in order to limit any negative impact on biodiversity. For example, neighboring farms could avoid simultaneous relocations, allowing wildlife to find alternative habitats nearby as each farm changes its methods.”

Gareth Jones from the University of Bristol said “We’ve known for a long time that organic farms often maintain higher biodiversity than similar conventional farms. The transition to organic farming has been little studied, however, and it would be an interesting future research project to determine whether the adverse effects during the transition observed here would be on other animals and plants.”

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