Abstract
In agricultural landscapes honeybees and other pollinators are exposed to pesticides, often surveyed by residue analysis of bee bread. However, bee bread is a mixture of pollen pellets of different plants collected over a longer time period. Therefore, pesticide content in the hive varies with plant species and time of pollen collection. Hence, the analysis of bee bread is an approximate approach to gain information on detailed pesticide exposure during the agronomic active season. As high-resolution data is missing, we carried out a pesticide residue survey over five years (2012–2016) of daily collected pollen pellets at three agricultural distinct sites in southern Germany. 281 single day pollen samples were selected and subjected to a multi-pesticide residue analysis. Pesticide contaminations of pollen differed between the sites. Intensive pesticide exposure can be seen by high pesticide concentrations as well as a high amount of different pesticides detected. During the five years of observation 73 different pesticides were found, of which 84% are characterized as non-harmful to honeybees. To estimate pesticide risks for honeybees, the pollen hazard quotient (PHQ) was calculated. Even though pesticides were detected in sublethal concentrations, we found substances not supposed to be exposed to honey bees, indicating the necessity for further improvement of seed treatments and increasing awareness of flowering shrubs, field margins and pesticide drift. Additionally, an in-depth analysis of nine pollen samples, divided into sub-fractions dominated by single plant species, revealed even higher concentrations in single crops for some pesticides. We give precise residue data of 1,657 single pesticide detections, which should be used for realistic laboratory and field tests.
Highlights
Integrated pest management, including chemical crop protection, is an approach by farmers to ensure crop yield [1]
The least intensive chemical crop protection activity was identified at the “meadow” site, considering number of detected pesticides, number of pesticide detections and maximum pesticide concentrations
This long-term study provides for the first time detailed information on the daily pesticide intake into honeybee colonies through pollen foragers during the agronomic active season
Summary
Integrated pest management, including chemical crop protection, is an approach by farmers to ensure crop yield [1]. Facing a growing world population, it is crucial to guarantee continuous high yields on the available arable land but avoiding negative impacts on the environment at the same time [3]. The latter includes the protection of the farmland and the safety of the produced crops for the consumer. High yield is influenced by crop protection, production site, agricultural practice or cultivar and by optimized pollination services [1,2,4,5]. Pollination is one of the most important services provided by honeybees (Apis mellifera L.), the most abundant pollinators in intensively managed agroecosystems due to a loss of wild pollinators [4,6,7,8]
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