Publications by authors named "Alexis P Roodt"

Terrestrial insectivores in riparian areas, such as spiders, can depend on emergent aquatic insects as high-quality prey. However, chemical pollution entering streams from agricultural and urban sources can alter the dynamics and composition of aquatic insect emergence, which may also affect the riparian food web. Few studies have examined the effects of stressor-induced alterations in aquatic insect emergence on spiders, especially in terms of chemical pollution and diet composition.

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Pesticides enter non-target surface waters as a result of agricultural activities and may reach water bodies in protected areas. We measured in southwestern Germany pesticide concentrations after heavy rainfalls in streams of a drinking water protection area near Hausen (Freiburg) and in the catchment of the Queich (Landau), which originates from the biosphere reserve Palatinate Forest. On average, 32 (n = 21) and 21 (n = 10) pesticides were detected per sample and event in the area of Hausen (n = 56) and in the Queich catchment (n = 17), respectively.

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Streams and their riparian areas are important habitats and foraging sites for bats feeding on emergent aquatic insects. Chemical pollutants entering freshwater streams from agricultural and wastewater sources have been shown to alter aquatic insect emergence, yet little is known about how this impacts insectivorous bats in riparian areas. In this study, we investigate the relationships between the presence of wastewater effluent, in-stream pesticide toxicity, the number of emergent and flying aquatic insects, and the activity and hunting behaviour of bats at 14 streams in southwestern Germany.

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Current-use pesticides are ubiquitous in freshwaters globally, often at very low concentrations. Emerging aquatic insects can accumulate pesticides during their aquatic development, which can be retained through their metamorphosis into terrestrial adults. Emerging insects thus provide a potential, yet largely understudied linkage for exposure of terrestrial insectivores to waterborne pesticides.

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Anthropogenic stressors can affect the emergence of aquatic insects. These insects link aquatic and adjacent terrestrial food webs, serving as high-quality subsidy to terrestrial consumers, such as spiders. While previous studies have demonstrated that changes in the emergence biomass and timing may propagate across ecosystem boundaries, the physiological consequences of altered subsidy quality for spiders are largely unknown.

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Exposure of freshwater ecosystems to insecticides can negatively impact the development of emerging aquatic insects. These insects serve as an important nutritional subsidy for terrestrial insectivores. Changes in insect emergence phenology (i.

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Emerging aquatic insects have the potential to retain aquatic contaminants after metamorphosis, potentially transporting them into adjacent terrestrial food webs. It is unknown whether this transfer is also relevant for current-use pesticides. We exposed larvae of the nonbiting midge, , to a sublethal pulse of a mixture of nine moderately polar fungicides and herbicides (log 2.

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Metals and organic contaminants in aquatic systems affect the coupling of aquatic and terrestrial ecosystems through two pathways: contaminant-induced effects on insect emergence and emergence-induced contaminant transfer. Consequently, the impact of aquatic contaminants on terrestrial ecosystems can be driven by modifications in the quantity and quality of adult aquatic insects serving as prey or contaminants entering terrestrial food webs as part of the diet of terrestrial predators. Here, we provide an overview of recent advances in the field, separating metals from organic contaminants due to their differential propensity to bioaccumulate and thus their potential contribution to either of the two pathways.

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Volatile organic compounds (VOCs) emanating from the surfaces of human skin are of great interest to researchers in medical and forensic fields, as well as to biologists studying the ecology of blood-feeding insect vectors of human disease. Research involving the comparison of relative abundances of VOCs emanating from human skin is currently limited by the methodology used for sample collection and pre-concentration. The use of in-house developed silicone rubber (polydimethylsiloxane (PDMS)) passive sampling devices constructed in the form of bracelets and anklets was explored to address this need.

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