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dc.contributor.authorChen, Kun
dc.date.accessioned2014-09-11T22:00:12Z
dc.date.available2014-09-11T22:00:12Z
dc.date.issued2014
dc.identifier.citationChen, Kun. Effects of Different Temperatures and Exposure Times on the Survival and DNA Damage of Collembolans (Springtails) in Response to Esfenvalerate (Sumi-Alpha) Soil Exposure. Master thesis, University of Oslo, 2014
dc.identifier.urihttp://hdl.handle.net/10852/40938
dc.description.abstractThere are multiple environmental factors that can affect the toxicity of a chemical to an organism in its natural environment. These include temperature, humidity, predation, competition, diseases, and presence of other chemicals. Due to this, extrapolation from laboratory to field conditions in a risk assessment is challenging. While low concentrations of a chemical may cause significant sub-lethal effect, such as DNA damage, which are not visible at the individual performance level, higher concentrations may affect endpoints of direct ecological relevance such as survival and reproduction. By including more than one endpoint in a toxicity study, the different levels of responses of the organisms can also be compared. Collembolans lives worldwide in the upper layer of soil, they have small body size and a short life cycle. They are generally considered sensitive to chemical changes in the soil, which makes them suitable as test organisms in toxicity studies. Collembola constitute a diverse group when it comes to living environment, taxonomy and physiology, and these differences may manifest as differences in sensitivity to chemicals between species. To add insight into how temperature and exposure time could affect the toxicity of a commonly used pesticide to collembolans, a series of experiments were performed in which two species of collembola (Folsomia quadrioculata and Onychiurus sp. separately exposed in soil) were investigated for lethal and sub-lethal responses to the chemical esfenvalerate. Both temperature and exposure time is especially relevant to risk assessment of pesticides used in Norway as soil temperatures here are much lower than that used in standard laboratory tests and most pesticides degrade more slowly at low temperatures (with longer exposure as a result). Toxicity of a fixed concentration series of esfenvalerate in the form of the commercial product "Sumi-Alpha" was investigated for both collembola species at three different temperatures (5℃, 10℃, and 20℃) for short-term exposure (1 week) and at 20℃ for long-term (5 weeks) exposure. From the short-term exposure experiments, survival was assessed for both species and DNA damage in the Onychiurus sp. In long-term experiments, survival and reproduction were measured for both species, so did the DNA damage for Onychiurus sp. Effects on survival (LC50) in short-term studies ranged from 44 to 50 mg/kg soil for F. quadrioculata and 53 to 54 mg/kg soil for Onychiurus sp. In long-term studies, LC50-values were lower; 30 mg/kg soil for F. quadrioculata and 30 mg/kg soil for Onychiurus sp. In long-term experiments, reproduction was insignificantly affected for both species already at the lowest exposure concentration (20 mg/kg soil for F. quadrioculata and 25 mg/kg soil for Onychiurus sp). DNA damage between different exposure durations on Onychiurus sp. was significant (P<0.001), and the estimated 50% effect concentration was 30 mg/kg. There was only a small difference in sensitivity between the two species, for all endpoints and exposure times. LC50 values were lower at long-term exposure compared to short-term exposure for both species (F. quadrioculata: P=0.0867, n=4; Onychiurus sp.: P=0.0001, n=4). From the results of this study, exposure temperatures in the range of 5-20 ℃ and exposure times in the range of 1 to 5 weeks do not seem to have a very large influence on the toxicity of esfenvalerate to soil-dwelling collembolans.nor
dc.language.isonor
dc.subjectCollembola
dc.subjectEsfenvalerate
dc.subjectSurvival
dc.subjectDNA
dc.subjectdamage
dc.subjectSub
dc.subjectlethal
dc.subjectEffect
dc.subjectComet
dc.subjectAssay
dc.subjectNeutral
dc.subjectRed
dc.subjectAssay
dc.titleEffects of Different Temperatures and Exposure Times on the Survival and DNA Damage of Collembolans (Springtails) in Response to Esfenvalerate (Sumi-Alpha) Soil Exposurenor
dc.titleEffects of Different Temperatures and Exposure Times on the Survival and DNA Damage of Collembolans (Springtails) in Response to Esfenvalerate (Sumi-Alpha) Soil Exposureeng
dc.typeMaster thesis
dc.date.updated2014-09-11T22:00:18Z
dc.creator.authorChen, Kun
dc.identifier.urnURN:NBN:no-45582
dc.type.documentMasteroppgave
dc.identifier.fulltextFulltext https://www.duo.uio.no/bitstream/handle/10852/40938/1/Masters-thesis--Kun-Chen.pdf


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