How Does Changing Pesticide Usage Over Time Affect Migrating Amphibians: A Case Study on the Use of Glyphosate-Based Herbicides in German Agriculture Over 20 Years

Abstract

Since its introduction in 1974, the use of glyphosate in agriculture has been continuously increasing; however, the application modes of this herbicide have been changing. Therefore, glyphosate-based herbicides can be used as an appropriate indicator for assessing how changes in pesticide application modes affect wild-living organisms in agricultural landscapes over time. Amphibians that migrate through arable fields may be exposed to the chemicals applied to field crops. Using data on the temporal coincidence of four amphibian populations with glyphosate applications from a three-year investigation in northeast Germany as well as data on the application of glyphosate to field crops in German agriculture over 20 years, we estimated the species-specific increasing rates of coincidence likelihoods during this period. The overall consumption of glyphosate used in German agriculture between 1992 and 2012 increased by a factor of 5.7, while the species-specific coincidence likelihood increased from 2.2 to 6.1, respectively. Our results reveal the highest increases in coincidence for both adult and juvenile great crested newt (Triturus cristatus) and fire-bellied toad (Bombina bombina). Adults and juveniles of moor frog (Rana arvalis) and adults of spadefoot toad (Pelobates fuscus) were subjected to moderate increases, with rates ranging from 3.2 to 3.6; in contrast, juvenile individuals of P. fuscus showed small increases. We suggest that the risk assessments of pesticide application (in this case, glyphosate) should not only consider the present use at the time of authorization but also consider changes in application modes over time that may lead to increases in potential exposure of non-target organisms, such as amphibians.

Re-registration Challenges of Glyphosate in the European Union

“…The increasing boost after 1990 was clearly due to the worldwide introduction of GT crops, and this growth in consumption was further intensified with the expansion of the use of multiple trait (stacked genetic events) GM crops. Nonetheless, the use of glyphosate increased in regions without GM crop cultivation (due to pre-harvest or post-harvest chemical desiccation) as well: the overall consumption of glyphosate in Germany was boosted 5.7-fold between 1992 and 2012 (Berger et al, 2018). Thus, since 2012 glyphosate alone represented globally a stable 12% of the overall pesticide market and 13% of the market for synthetic pesticides (BCC Research, 2012;Transparency Market Research, 2014.…”

Citizen science involving farmers as a means to document temporal trends in farmland biodiversity and relate them to agricultural practices

“…Among them, Hallmann, Foppen, van Turnhout, de Kroon, and Jongejans (2014) linked the introduction of neonicotinoids to a negative trend in insectivorous bird populations by comparing different periods of surveys (before/after). Berger et al (2018) observed a relationship between changes in glyphosate application modes and amphibian migration. Finally, Seibold et al (2019) showed a general decline of arthropods driven by land-use intensification at large spatial extent.…”

From microbes to mammals: pond biodiversity homogenization across different land-use types in an agricultural landscape

“…Concomitantly, crop diversity decreased by more than 30% while the total crop coverage of land increased (Meyer et al 2013). These changes in agricultural practice had negative consequences on biodiversity, resulting in declining plant (Meyer et al 2013, Altenfelder et al 2014, bird (Donald et al 2006), invertebrate (Wilson et al 1999) and amphibian (Berger et al 2011(Berger et al , 2018 diversity. Furthermore, plant communities became homogenized (Macdonald andJohnson 2000, Baessler andKlotz 2006), as has commonly been observed after land-use intensification (Smart et al 2006).…”