Farmland biodiversity is an important characteristic when assessing sustainability of agricultural practices and is of major international concern. Scientific data indicate that agricultural intensification and pesticide use are among the main drivers of biodiversity loss. The analysed data and experiences do not support statements that herbicide-resistant crops provide consistently better yields than conventional crops or reduce herbicide amounts. They rather show that the adoption of herbicide-resistant crops impacts agronomy, agricultural practice, and weed management and contributes to biodiversity loss in several ways: (i) many studies show that glyphosate-based herbicides, which were commonly regarded as less harmful, are toxic to a range of aquatic organisms and adversely affect the soil and intestinal microflora and plant disease resistance; the increased use of 2,4-D or dicamba, linked to new herbicide-resistant crops, causes special concerns. (ii) The adoption of herbicide-resistant crops has reduced crop rotation and favoured weed management that is solely based on the use of herbicides. (iii) Continuous herbicide resistance cropping and the intensive use of glyphosate over the last 20 years have led to the appearance of at least 34 glyphosate-resistant weed species worldwide. Although recommended for many years, farmers did not counter resistance development in weeds by integrated weed management, but continued to rely on herbicides as sole measure. Despite occurrence of widespread resistance in weeds to other herbicides, industry rather develops transgenic crops with additional herbicide resistance genes. (iv) Agricultural management based on broad-spectrum herbicides as in herbicide-resistant crops further decreases diversity and abundance of wild plants and impacts arthropod fauna and other farmland animals. Taken together, adverse impacts of herbicide-resistant crops on biodiversity, when widely adopted, should be expected and are indeed very hard to avoid. For that reason, and in order to comply with international agreements to protect and enhance biodiversity, agriculture needs to focus on practices that are more environmentally friendly, including an overall reduction in pesticide use. (Pesticides are used for agricultural as well non-agricultural purposes. Most commonly they are used as plant protection products and regarded as a synonym for it and so also in this text.)

This paper presents a pilot project conducted by ISPRA and ARPA Campania to develop a monitoring protocol to detect the presence of genetically modified (GM) oilseed rape (Brassica napus) plants resulting from accidental seed dispersal during transportation from entry points to storage and processing facilities; the project has been implemented in Italy’s Campania region. The unintentional dispersal of GM oilseed rape seeds and the potential establishment of feral populations have been identified as environmental concerns in various countries, even when GM oilseed rape is imported solely for processing and not for cultivation. The project activities were designed, taking into account the characteristics of the Italian environment and infrastructures. Multiple sampling campaigns were conducted in autumn 2018, spring 2019, and autumn 2019 to validate the selected transects and assess the presence of Brassicaceae species, with a particular focus on oilseed rape. These efforts involved direct monitoring and sample collection along transport routes from the port of Salerno to seed companies in the provinces of Benevento and Caserta. Field observations and import data revealed a decrease in oilseed rape movement at the port of Salerno in the years preceding the survey, while seed companies near Benevento remained active sites for white mustard (Sinapis alba). The presence of S. alba and the simultaneous occurrence of oilseed rape and Raphanus raphanistrum—a species with high hybridization potential—support the hypothesis that seed companies may act as hotspots for accidental seed dispersal and that potential interspecific gene flow can occur. The study also validated the adopted sampling and molecular analysis methods, including DNA extraction and PCR, for the detection of the Cruciferin A (CruA) gene in all Brassica species collected. These findings highlight the need to strengthen post-marketing monitoring plans, even when GM rapeseed is imported solely for processing, to mitigate the potential risks associated with unintended gene flow.