Rebelo, Maria Teresa Ferreira Ramos Nabais de Oliveira, 1964-Borgå, KatrineSilva, Andreia Sofia Jorge2023-02-012023-02-0120212021http://hdl.handle.net/10451/56094Tese de mestrado, Biologia Humana e Ambiente, 2021, Universidade de Lisboa, Faculdade de CiênciasNeonicotinoids are the most widely used insecticides worldwide. A large proportion ends up in the soil, where they degrade slowly, and are likely to affect non-target species in the soil community, such as Collembola (springtails). Springtails play an important role in soil ecosystems by contributing to litter decomposition and nutrient cycling. Standard toxicity tests use soil exposure to toxicants, which does not allow for detailed observation of the individuals during the experiment. These tests are developed to expose organisms through soil to certain types of contaminants, but in nature springtails can also be exposed to them through their diet. We therefore aimed to, and successfully developed, a method for dietary exposure to toxicants, allowing us to observe springtails performance during exposure. The neonicotinoid imidacloprid was applied as a test substance, and we studied two springtail species, Folsomia quadrioculata and Hypogastrura viatica, with different life histories, habitat, and ecology, to assess potential difference in sensitivity. For each species, five replicates of 20 newly hatched animals were exposed through feed treated with one of two different applications: moistening the feed with a micropipette (estimated final concentration of 129 mg/kg imidacloprid) or soaking it in a solution with 129 ug/L imidacloprid, at room temperature. Moistening the Tilia cordata bark was most accurate, giving concentrations similar to the estimated nominal ones, while soaking resulted in 38 times higher concentrations than moistened measured method. With our established method of moistening the bark, we conducted a concentration-response experiment to study how imidacloprid affects different life history traits in juvenile H. viatica using 5 sub-lethal concentrations from 0.01 to 1.2 mg/kg dry bark. Due to time constraints as a result of the COVID-19 pandemic, which prevented access to the laboratory, it was difficult to analyze some endpoints for Folsomia quadrioculata, and since it was possible to register molting and measure body size in Hypogastrura viatica we conducted the second experiment only on that species. Exposure to the soil relevant concentrations of imidacloprid caused H. viatica to reach maturity late, reduced its molting frequency, and thus reduced its body size. Since these endpoints have negative impacts on Collembola egg production, the studied neonicotinoid shown negative effects on population growth and may therefore cause population-level effects. There is still little information about these two springtails species and especially on the life history traits for springtails in general. Therefore, in the future it would be important to use methods that allow the monitoring of effects on life history traits.engColêmbolosNeonicotinóidesImidaclopridaMétodo de alimentaçãoExposição concentração-respostaTeses de mestrado - 2021master thesis202934438