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Factors behind intraspecific variation in sensitivity to pathogens remain poorly understood. We investigated how geographical origin in two North European amphibians affects tolerance to infection by the chytrid fungus Batrachochytrium dendrobatidis (Bd), a generalist pathogen which has caused amphibian population declines worldwide. We exposed newly metamorphosed individuals of moor frog Rana arvalis and common toad Bufo bufo from two latitudinal regions to two different BdGPL strains. We measured survival and growth as infections may cause sub-lethal effects in fitness components even in the absence of mortality. Infection loads were higher in B. bufo than in R. arvalis, and smaller individuals had generally higher infection loads. B. bufo had high mortality in response to Bd infection, whereas there was little mortality in R. arvalis. Bd-mediated mortality was size-dependent and high-latitude individuals were smaller leading to high mortality in the northern B. bufo. Bd exposure led to sub-lethal effects in terms of reduced growth suggesting that individuals surviving the infection may have reduced fitness mediated by smaller body size. In both host species, the Swedish Bd strain caused stronger sublethal effects than the British strain. We suggest that high-latitude populations can be more vulnerable to chytrids than those from lower latitudes and discuss the possible mechanisms how body size and host geographical origin contribute to the present results.

Factors behind intraspecific variation in sensitivity to pathogens remain poorly understood. We investigated how geographical origin in two North European amphibians affects tolerance to infection by the chytrid fungus Batrachochytrium dendrobatidis (Bd), a generalist pathogen which has caused amphibian population declines worldwide. We exposed newly metamorphosed individuals of moor frog Rana arvalis and common toad Bufo bufo from two latitudinal regions to two different BdGPL strains. We measured survival and growth as infections may cause sub-lethal effects in fitness components even in the absence of mortality. Infection loads were higher in B. bufo than in R. arvalis, and smaller individuals had generally higher infection loads. B. bufo had high mortality in response to Bd infection, whereas there was little mortality in R. arvalis. Bd-mediated mortality was size-dependent and high-latitude individuals were smaller leading to high mortality in the northern B. bufo. Bd exposure led to sub-lethal effects in terms of reduced growth suggesting that individuals surviving the infection may have reduced fitness mediated by smaller body size. In both host species, the Swedish Bd strain caused stronger sublethal effects than the British strain. We suggest that high-latitude populations can be more vulnerable to chytrids than those from lower latitudes and discuss the possible mechanisms how body size and host geographical origin contribute to the present results.

Factors behind intraspecific variation in sensitivity to pathogens remain poorly understood. We investigated how geographical origin in two North European amphibians affects tolerance to infection by the chytrid fungus Batrachochytrium dendrobatidis (Bd), a generalist pathogen which has caused amphibian population declines worldwide. We exposed newly metamorphosed individuals of moor frog Rana arvalis and common toad Bufo bufo from two latitudinal regions to two different BdGPL strains. We measured survival and growth as infections may cause sub-lethal effects in fitness components even in the absence of mortality. Infection loads were higher in B. bufo than in R. arvalis, and smaller individuals had generally higher infection loads. B. bufo had high mortality in response to Bd infection, whereas there was little mortality in R. arvalis. Bd-mediated mortality was size-dependent and high-latitude individuals were smaller leading to high mortality in the northern B. bufo. Bd exposure led to sub-lethal effects in terms of reduced growth suggesting that individuals surviving the infection may have reduced fitness mediated by smaller body size. In both host species, the Swedish Bd strain caused stronger sublethal effects than the British strain. We suggest that high-latitude populations can be more vulnerable to chytrids than those from lower latitudes and discuss the possible mechanisms how body size and host geographical origin contribute to the present results.

Factors behind intraspecific variation in sensitivity to pathogens remain poorly understood. We investigated how geographical origin in two North European amphibians affects tolerance to infection by the chytrid fungus Batrachochytrium dendrobatidis (Bd), a generalist pathogen which has caused amphibian population declines worldwide. We exposed newly metamorphosed individuals of moor frog Rana arvalis and common toad Bufo bufo from two latitudinal regions to two different BdGPL strains. We measured survival and growth as infections may cause sub-lethal effects in fitness components even in the absence of mortality. Infection loads were higher in B. bufo than in R. arvalis, and smaller individuals had generally higher infection loads. B. bufo had high mortality in response to Bd infection, whereas there was little mortality in R. arvalis. Bd-mediated mortality was size-dependent and high-latitude individuals were smaller leading to high mortality in the northern B. bufo. Bd exposure led to sub-lethal effects in terms of reduced growth suggesting that individuals surviving the infection may have reduced fitness mediated by smaller body size. In both host species, the Swedish Bd strain caused stronger sublethal effects than the British strain. We suggest that high-latitude populations can be more vulnerable to chytrids than those from lower latitudes and discuss the possible mechanisms how body size and host geographical origin contribute to the present results.

Factors behind intraspecific variation in sensitivity to pathogens remain poorly understood. We investigated how geographical origin in two North European amphibians affects tolerance to infection by the chytrid fungus Batrachochytrium dendrobatidis (Bd), a generalist pathogen which has caused amphibian population declines worldwide. We exposed newly metamorphosed individuals of moor frog Rana arvalis and common toad Bufo bufo from two latitudinal regions to two different BdGPL strains. We measured survival and growth as infections may cause sub-lethal effects in fitness components even in the absence of mortality. Infection loads were higher in B. bufo than in R. arvalis, and smaller individuals had generally higher infection loads. B. bufo had high mortality in response to Bd infection, whereas there was little mortality in R. arvalis. Bd-mediated mortality was size-dependent and high-latitude individuals were smaller leading to high mortality in the northern B. bufo. Bd exposure led to sub-lethal effects in terms of reduced growth suggesting that individuals surviving the infection may have reduced fitness mediated by smaller body size. In both host species, the Swedish Bd strain caused stronger sublethal effects than the British strain. We suggest that high-latitude populations can be more vulnerable to chytrids than those from lower latitudes and discuss the possible mechanisms how body size and host geographical origin contribute to the present results.

Native and invasive species often occupy similar ecological niches and environments where they face comparable risks from chemical exposure. Sometimes, invasive species are phylogenetically related to native species, e.g. they may come from the same family and have potentially similar sensitivities to environmental stressors due to phylogenetic conservatism and ecological similarity. However, empirical studies that aim to understand the nuanced impacts of chemicals on the full range of closely related species are rare, yet they would help to comprehend patterns of current biodiversity loss and species turnover. Behavioral sublethal endpoints are of increasing ecotoxicological interest. Therefore, we investigated behavioral responses (i.e., change in movement behavior) of the four dominant amphipod species in the Rhine-Main area (central Germany) when exposed to the neonicotinoid thiacloprid. Moreover, beyond species-specific behavioral responses, ecological interactions (e.g. parasitation with Acanthocephala) play a crucial role in shaping behavior, and we have considered these infections in our analysis. Our findings revealed distinct baseline behaviors and species-specific responses to thiacloprid exposure. Notably, Gammarus fossarum exhibited biphasic behavioral changes with hyperactivity at low concentrations that decreased at higher concentrations. Whereas Gammarus pulex, Gammarus roeselii and the invasive species Dikerogammarus villosus, showed no or weaker behavioral responses. This may partly explain why G. fossarum disappears in chemically polluted regions while the other species persist there to a certain degree. But it also shows that potential pre-exposure in the habitat may influence behavioral responses of the other amphipod species, because habituation occurs, and potential hyperactivity would be harmful to individuals in the habitat. The observed responses were further influenced by acanthocephalan parasites, which altered baseline behavior in G. roe

Factors behind intraspecific variation in sensitivity to pathogens remain poorly understood. We investigated how geographical origin in two North European amphibians affects tolerance to infection by the chytrid fungus Batrachochytrium dendrobatidis (Bd), a generalist pathogen which has caused amphibian population declines worldwide. We exposed newly metamorphosed individuals of moor frog Rana arvalis and common toad Bufo bufo from two latitudinal regions to two different BdGPL strains. We measured survival and growth as infections may cause sub-lethal effects in fitness components even in the absence of mortality. Infection loads were higher in B. bufo than in R. arvalis, and smaller individuals had generally higher infection loads. B. bufo had high mortality in response to Bd infection, whereas there was little mortality in R. arvalis. Bd-mediated mortality was size-dependent and high-latitude individuals were smaller leading to high mortality in the northern B. bufo. Bd exposure led to sub-lethal effects in terms of reduced growth suggesting that individuals surviving the infection may have reduced fitness mediated by smaller body size. In both host species, the Swedish Bd strain caused stronger sublethal effects than the British strain. We suggest that high-latitude populations can be more vulnerable to chytrids than those from lower latitudes and discuss the possible mechanisms how body size and host geographical origin contribute to the present results.

Background: Pesticides are identified as one of the major reasons for the global pollinator decline. However, the sublethal effects of pesticide residue levels found in pollen and nectar on pollinators have been studied little. The aim of our research was to study whether oral exposure to the thiacloprid levels found in pollen and nectar affect the learning and long-term memory of bumble bees. We tested the effects of two exposure levels of thiacloprid-based pesticide (Calypso SC480) on buff-tailed bumble bee (Bombus terrestris) in laboratory utilizing a learning performance and memory tasks designed to be difficult enough to reveal large variations across the individuals. Results: The lower exposure level of the thiacloprid-based pesticide impaired the bees’ learning performance but not long-term memory compared to the untreated controls. The higher exposure level caused severe acute symptoms, due to which we were not able to test the learning and memory. Conclusions: Our results show that oral exposure to a thiacloprid-based pesticide, calculated based on residue levels found in pollen and nectar, not only causes sublethal effects but also acute lethal effects on bumble bees. Our study underlines an urgent demand for better understanding of pesticide residues in the environment, and of the effects of those residue levels on pollinators. These findings fill the gap in the existing knowledge and help the scientific community and policymakers to enhance the sustainable use of pesticides.

A variety of veterinary and human medicinal products (VHMPs) are found in groundwater, an often-neglected habitat inhabited by species with unique traits, stygobitic species. It is crucial to understand the effect of VHMPs on stygobitic species because they may respond differently to stressors than surface species. Our hypothesis is that groundwater species may be more susceptible to environmental contaminants due to less plasticity in their detoxification response and acquisition of energy because subterranean habitats are more stable and isolated from anthropogenic activities. We performed a battery of biomarkers associated with important physiological functions on the stygobitic asellid crustacean Proasellus lusitanicus, after a 14-day exposure to acetaminophen, a commonly used pharmaceutical and pollutant of groundwaters. Our results show a decrease in total glutathione levels and an increase in glutathione S-transferase activity, suggesting a successful detoxification response. This helps explaining why acetaminophen did not cause oxidative damage, as well as had no effect on cholinesterase activity nor in aerobic production of energy. This study shows the remarkable capacity of P. lusitanicus to tolerate sublethal concentrations of VHMP acetaminophen. Most ecotoxicological studies on stygobitic species focused on the lethal effects of these compounds. The present study focuses on consequences at sublethal concentrations. Future studies should assess the stress levels induced to better predict and estimate the impacts of contaminants on groundwater ecosystems.

The effects of hexythiazox on life-history traits and demographic parameters of Tetranychus urticae Koch (Acari: Tetranychidae) were evaluated using the age-stage two-sex life table (in fecundity-based and fertility-based variants), with emphasis on its transovarial toxicity. Hexythiazox was applied when T. urticae females were either in the preovipositional period or in the first day of oviposition. In the F-0 generation bioassay, treatments with concentrations of 50, 12.5 and 3.125 mg/l significantly reduced the longevity of females and their fecundity. These effects were mostly the result of mortality of treated females (18-23%) over the 24-h exposure period. Even though the net reproductive rate (R-0) decreased significantly, the intrinsic rate of increase (r), finite rate of increase (lambda) and doubling time (D) were not significantly different from the control. The strongest transovarial toxic effect occurred within the first 4 days following treatment, when 52-89% of the eggs laid by treated females (96% in control) hatched. Fertility was significantly reduced by concentrations of 50, 12.5, 3.125, 0.781 and 0.195 mg/l. These concentrations caused significant reductions in R-0 (34-54%), r (12-24%) and lambda (3-5%), whereas D was extended for 0.4-0.7 days. In the F-1 generation bioassay, 50, 12.5, 3.125, 0.781, 0.049 and 0.012 mg/l caused significant reductions in R-0 (34-92%), r (10-68%) and lambda (3-17%), whereas extending D for 0.3-5.6 days. These effects were mostly the consequence of transovarial toxicity. Application of the fecundity-based life table underestimated population-level effects of hexythiazox on T. urticae.

Foraging is essential for honey bee colony fitness and is enhanced by the waggle dance, a recruitment behavior in which bees can communicate food location and quality. We tested if the consumption of nectar (sucrose solution) with a field-realistic concentration of 4 ppm flupyradifurone (FPF) could alter foraging behavior and recruitment dancing in Apis mellifera. Foragers were repelled by FPF. They visited the FPF feeder less often and spent less time imbibing sucrose solution (2.5 M, 65% w/w) with FPF. As a result, bees feeding on the FPF treatment consumed 16% less nectar. However, FPF did not affect dancing: there were no effects on unloading wait time, the number of dance bouts per nest visit, or the number of dance circuits performed per dance bout. FPF could therefore deter bees from foraging on contaminated nectar. However, the willingness of bees to recruit nestmates for nectar with FPF is concerning. Recruitment can rapidly amplify the number of foragers and could overcome the decrease in consumption of FPF-contaminated nectar, resulting in a net inflow of pesticide to the colony. FPF also significantly altered the expression of 116 genes, some of which may be relevant for the olfactory learning deficits induced by FPF and the toxicity of FPF.

Life-history traits determine individual fitness and the fate of populations. Imidacloprid, a widely used neonicotinoid insecticide, which persists in soil for more than 100 d at biologically relevant levels, may affect nontarget and ecologically important species, such as collembolans. In the present study, we determined the sublethal effects of short-term imidacloprid exposure and postexposure recovery in the collembolan Folsomia quadrioculata, which occurs abundantly across the northern hemisphere. We assessed survival, egg production, and hatching success in adult springtails exposed for 14 d through the diet to imidacloprid, followed by a 28-d postexposure phase. Survival and hatching success were high throughout the experiment in all the treatments, with no clear concentration dependence. However, egg production declined during the exposure phase and nearly stopped between 8 and 14 d in all the treatments (except the control) but resumed during the postexposure phase. Moreover, the resumption of egg production showed a concentration-dependent delay. Our findings suggest that low imidacloprid exposures can restrict reproduction, with potentially severe consequences for the population, notwithstanding the partial recovery in egg production.

Research on the ‘ecology of fear’ posits that defensive prey responses to avoid predation can cause non-lethal effects across ecological scales. Parasites also elicit defensive responses in hosts with associated non-lethal effects, which raises the longstanding, yet unresolved question of how non-lethal effects of parasites compare with those of predators. We developed a framework for systematically answering this question for all types of predator–prey and host–parasite systems. Our framework reveals likely differences in non-lethal effects not only between predators and parasites, but also between different types of predators and parasites. Trait responses should be strongest towards predators, parasitoids and parasitic castrators, but more numerous and perhaps more frequent for parasites than for predators. In a case study of larval amphibians, whose trait responses to both predators and parasites have been relatively well studied, existing data indicate that individuals generally respond more strongly and proactively to short-term predation risks than to parasitism. Apart from studies using amphibians, there have been few direct comparisons of responses to predation and parasitism, and none have incorporated responses to micropredators, parasitoids or parasitic castrators, or examined their long-term consequences. Addressing these and other data gaps highlighted by our framework can advance the field towards understanding how non-lethal effects impact prey/host population dynamics and shape food webs that contain multiple predator and parasite species.

Foraging is essential for honey bee colony fitness and is enhanced by the waggle dance, a recruitment behavior in which bees can communicate food location and quality. We tested if the consumption of nectar (sucrose solution) with a field-realistic concentration of 4 ppm flupyradifurone (FPF) could alter foraging behavior and recruitment dancing in Apis mellifera. Foragers were repelled by FPF. They visited the FPF feeder less often and spent less time imbibing sucrose solution (2.5 M, 65% w/w) with FPF. As a result, bees feeding on the FPF treatment consumed 16% less nectar. However, FPF did not affect dancing: there were no effects on unloading wait time, the number of dance bouts per nest visit, or the number of dance circuits performed per dance bout. FPF could therefore deter bees from foraging on contaminated nectar. However, the willingness of bees to recruit nestmates for nectar with FPF is concerning. Recruitment can rapidly amplify the number of foragers and could overcome the decrease in consumption of FPF-contaminated nectar, resulting in a net inflow of pesticide to the colony. FPF also significantly altered the expression of 116 genes, some of which may be relevant for the olfactory learning deficits induced by FPF and the toxicity of FPF.

Research on the 'ecology of fear' posits that defensive prey responses to avoid predation can cause non-lethal effects across ecological scales. Parasites also elicit defensive responses in hosts with associated non-lethal effects, which raises the longstanding, yet unresolved question of how non-lethal effects of parasites compare with those of predators. We developed a framework for systematically answering this question for all types of predator-prey and host-parasite systems. Our framework reveals likely differences in non-lethal effects not only between predators and parasites, but also between different types of predators and parasites. Trait responses should be strongest towards predators, parasitoids and parasitic castrators, but more numerous and perhaps more frequent for parasites than for predators. In a case study of larval amphibians, whose trait responses to both predators and parasites have been relatively well studied, existing data indicate that individuals generally respond more strongly and proactively to short-term predation risks than to parasitism. Apart from studies using amphibians, there have been few direct comparisons of responses to predation and parasitism, and none have incorporated responses to micropredators, parasitoids or parasitic castrators, or examined their long-term consequences. Addressing these and other data gaps highlighted by our framework can advance the field towards understanding how non-lethal effects impact prey/host population dynamics and shape food webs that contain multiple predator and parasite species.

Plutella xylostella is a major pest of cruciferous crops in more than 100 countries. The main control method for P. xylostella is based on the use of chemical insecticides. However, this moth species is characterized by its rapid development of resistance to almost all insecticides. The application of low concentrations of insecticides can affect the physiology, biochemistry, and ecology of insects. In this study, a cypermethrin resistance selection was performed during eight generations of P. xylostella and the sublethal dose (LC20) of the resistant line and the susceptible line was determined. Later, the sublethal dose was applied to third instar larvae to investigate its effect on the percentage of pupation, weight of pupae, emergence of adults in two generations (parents and offspring), as well as the development times of each phase of development of P xylostella. A decrease was observed in the percentage of formed pupae, emerged adults and pupal weight. On the other hand, the number of oviposited eggs increased when individuals were exposed to the insecticide. The above can be an important factor for the management and control of this pest when problems of resistance to cypermethrin occur., Resumen: Plutella xylostella es una importante plaga de cultivos de brassicas en más de 100 países. El principal método de control de P. xylostella se basa en el uso de insecticidas químicos. Sin embargo, esta especie se caracteriza por su rápido desarrollo de resistencia a casi todos los insecticidas. Se ha reportado que la aplicación de concentraciones bajas de insecticidas afecta la fisiología, bioquímica y ecología de los insectos. En este estudio, se realizó una selección de resistencia de cipermetrina durante ocho generaciones de P. xylostella y se determinó la dosis subletal (CL20) de la línea resistente y de la línea susceptible. Posteriormente, la dosis subletal se aplicó a larvas de tercer instar para investigar su efecto en el porcentaje de pupación, peso de pupas, emergencia de adultos en dos generaciones (progenitores y descendientes), así como los tiempos de desarrollo de cada fase de desarrollo de P. xylostella. Se observó una disminución el porcentaje de pupas formadas, adultos emergidos y peso de pupas. Por otro lado, el número de huevos depositados aumentó cuando los individuos fueron expuestos al insecticida. Lo anterior puede ser un factor importante para el manejo y control de esta plaga cuando se presenten problemas de resistencia a cipermetrina.

Plutella xylostella is a major pest of cruciferous crops in more than 100 countries. The main control method for P. xylostella is based on the use of chemical insecticides. However, this moth species is characterized by its rapid development of resistance to almost all insecticides. The application of low concentrations of insecticides can affect the physiology, biochemistry, and ecology of insects. In this study, a cypermethrin resistance selection was performed during eight generations of P. xylostella and the sublethal dose (LC20) of the resistant line and the susceptible line was determined. Later, the sublethal dose was applied to third instar larvae to investigate its effect on the percentage of pupation, weight of pupae, emergence of adults in two generations (parents and offspring), as well as the development times of each phase of development of P xylostella. A decrease was observed in the percentage of formed pupae, emerged adults and pupal weight. On the other hand, the number of oviposited eggs increased when individuals were exposed to the insecticide. The above can be an important factor for the management and control of this pest when problems of resistance to cypermethrin occur., Resumen: Plutella xylostella es una importante plaga de cultivos de brassicas en más de 100 países. El principal método de control de P. xylostella se basa en el uso de insecticidas químicos. Sin embargo, esta especie se caracteriza por su rápido desarrollo de resistencia a casi todos los insecticidas. Se ha reportado que la aplicación de concentraciones bajas de insecticidas afecta la fisiología, bioquímica y ecología de los insectos. En este estudio, se realizó una selección de resistencia de cipermetrina durante ocho generaciones de P. xylostella y se determinó la dosis subletal (CL20) de la línea resistente y de la línea susceptible. Posteriormente, la dosis subletal se aplicó a larvas de tercer instar para investigar su efecto en el porcentaje de pupación, peso de pupas, emergencia de adultos en dos generaciones (progenitores y descendientes), así como los tiempos de desarrollo de cada fase de desarrollo de P. xylostella. Se observó una disminución el porcentaje de pupas formadas, adultos emergidos y peso de pupas. Por otro lado, el número de huevos depositados aumentó cuando los individuos fueron expuestos al insecticida. Lo anterior puede ser un factor importante para el manejo y control de esta plaga cuando se presenten problemas de resistencia a cipermetrina.

With an ever-increasing amount of plastic pollution in the various aquatic ecosystems around the world, the effects on organisms are still not fully understood. Most studies focus on direct effects posed by plastic intake or entanglement, but plastic debris can also affect primary production of biofilms and have an indirect impact on its consumers. This study investigates the primary production on three common plastic types in freshwater and its food quality for a benthic grazer. We hypothesized that different polymer types affect biofilm composition as well as the life parameters of its consumers. We incubated polyethylene (PE), polyethylene terephthalate (PET) and polystyrene (PS) as well as glass (control) in a productive freshwater creek for natural biofilm establishment. To account for changes in the environmental conditions, the experiment was conducted twice during winter and late spring, respectively. These biofilms were offered to the freshwater gastropod Physa fontinalis as sole food source. Growth and reproduction of the snails were measured to monitor sublethal effects. Additionally, biofilm composition was observed using confocal laser scanning microscopy (CLSM). In winter, snails feeding off PET and PE showed a significantly lower egg production and lower growth rates were observed on PET. No such effects occurred in spring. CLSM data revealed, that algal growth was significantly lower on PE and PET during the winter treatment compared to PS and glass. Since we could only find these effects during the colder and darker months (January–March), the microbial colonization on PE and PET was inhibited by the substrate under less favorable conditions of temperature and light. Hence, benign conditions may mask the adverse effects of microplastic on food webs. Our findings show that future studies on the plastisphere will need to consider such variations to further understand the influence of plastic pollution on primary production and higher trophic levels.

Plutella xylostella is a major pest of cruciferous crops in more than 100 countries. The main control method for P. xylostella is based on the use of chemical insecticides. However, this moth species is characterized by its rapid development of resistance to almost all insecticides. The application of low concentrations of insecticides can affect the physiology, biochemistry, and ecology of insects. In this study, a cypermethrin resistance selection was performed during eight generations of P. xylostella and the sublethal dose (LC20) of the resistant line and the susceptible line was determined. Later, the sublethal dose was applied to third instar larvae to investigate its effect on the percentage of pupation, weight of pupae, emergence of adults in two generations (parents and offspring), as well as the development times of each phase of development of P xylostella. A decrease was observed in the percentage of formed pupae, emerged adults and pupal weight. On the other hand, the number of oviposited eggs increased when individuals were exposed to the insecticide. The above can be an important factor for the management and control of this pest when problems of resistance to cypermethrin occur., Resumen: Plutella xylostella es una importante plaga de cultivos de brassicas en más de 100 países. El principal método de control de P. xylostella se basa en el uso de insecticidas químicos. Sin embargo, esta especie se caracteriza por su rápido desarrollo de resistencia a casi todos los insecticidas. Se ha reportado que la aplicación de concentraciones bajas de insecticidas afecta la fisiología, bioquímica y ecología de los insectos. En este estudio, se realizó una selección de resistencia de cipermetrina durante ocho generaciones de P. xylostella y se determinó la dosis subletal (CL20) de la línea resistente y de la línea susceptible. Posteriormente, la dosis subletal se aplicó a larvas de tercer instar para investigar su efecto en el porcentaje de pupación, peso de pupas, emergencia de adultos en dos generaciones (progenitores y descendientes), así como los tiempos de desarrollo de cada fase de desarrollo de P. xylostella. Se observó una disminución el porcentaje de pupas formadas, adultos emergidos y peso de pupas. Por otro lado, el número de huevos depositados aumentó cuando los individuos fueron expuestos al insecticida. Lo anterior puede ser un factor importante para el manejo y control de esta plaga cuando se presenten problemas de resistencia a cipermetrina.

The herbicide oxadiazon is used as weed control in Colombia; however, the application of this substance, like other herbicides, can affect the fauna associated with bodies of water. The objective was to evaluate the lethal, sublethal, morphometric and teratological effects in Engystomopspustulosuslarvae exposed to this herbicide in three habitat volumes. Gosner stage 25 larvae were used and exposed for 96 hours to three volumes of habitat (40, 200 and 1000 mL) and three concentrations of the herbicide, with three replicates for each one. The LC50found for the tadpoles in a volume of 40 ml was 1.46mg/ L and in 1000 ml it was 1.5 mg / L. Regarding the sublethal effects, the abnormalities of prolonged quiet and curved tail were frequent in all volumes (from 27% to 70% and from 37% to 43%, respectively), even so, the regression analysis did not showa relationship between the volume variation and the appearance of abnormalities (p> 0.05). On the other hand, the body development of the tadpoles is related to the volume (p <0.05), because inlarger volumes tadpoles with larger sizes (3.10-3.25 mm, approximately) are observed compared to the deposited in a smaller volume (2.92-2.97 mm, approximately), regardless of the applied concentration. It is concluded that the herbicide Oxadiazon is toxic for volumes of 40mL and 1000 mL (LC501.46 mg / L and 1.5 mg / L) and that there is no statistically significant relationship (p> 0.05) between the volume and the appearance of abnormalities in exposed organisms, but there is a statistically significantrelationship (p <0.05) between volume and morphometric development., El herbicida oxadiazon es usado como control de malezas en Colombia; sin embargo, la aplicación de esta sustancia, al igual que la de otros herbicidas, puede afectar la fauna asociada a cuerpos de agua. El objetivo de este estudio fue evaluar los efectos letales, subletales, morfométricos y teratológicos en larvasde Engystomops pustulosusexpuestas a este herbicida en tres volúmenes de hábitat. Se utilizaron larvas en estado 25 de Gosner y se expusieron durante 96 horas atres volúmenes de hábitat (40, 200 y 1000 mL) y tres concentraciones del herbicida, con tres réplicas para cada uno.La CL50hallada para los renacuajos en un volumen de 40 mL fue 1,46 mg/L, y en 1000 mL fue de 1,5 mg/L. En cuanto a los efectos subletales, las anormalidades quietud prolongada y cola curvada fueron frecuentes en todos los volúmenes(de 27 % a 70 % y de 37 % a 43 %, respectivamente). Aun así, el análisis de regresión no mostró relación entre la variación del volumen y la aparición de anormalidades (p>0,05). En cambio, el desarrollo corporal de los renacuajos está relacionado con el volumen(p<0,05), debidoa que en volúmenes mayores se observan renacuajos con tallas superiores (3,10-3,25 mm, aproximadamente) en comparación con los depositados en un menor volumen (2,92-2,97 mm, aproximadamente), indistintamente de la concentración aplicada. Se concluye que el herbicida oxadiazon es tóxico para losvolúmenes de 40 mL y 1000 mL (CL501,46 mg/L y 1,5 mg/L) y que no existe una relación estadísticamente significativa (p>0,05) entre el volumen y la aparición de las anormalidades en los organismos expuestos, pero síhay una relación estadísticamente significativa (p<0,05) entre el volumen y el desarrollo morfométrico.

Life-history traits determine individual fitness and the fate of populations. Imidacloprid, a widely used neonicotinoid insecticide, which persists in soil for more than 100 d at biologically relevant levels, may affect nontarget and ecologically important species, such as collembolans. In the present study, we determined the sublethal effects of short-term imidacloprid exposure and postexposure recovery in the collembolan Folsomia quadrioculata, which occurs abundantly across the northern hemisphere. We assessed survival, egg production, and hatching success in adult springtails exposed for 14 d through the diet to imidacloprid, followed by a 28-d postexposure phase. Survival and hatching success were high throughout the experiment in all the treatments, with no clear concentration dependence. However, egg production declined during the exposure phase and nearly stopped between 8 and 14 d in all the treatments (except the control) but resumed during the postexposure phase. Moreover, the resumption of egg production showed a concentration-dependent delay. Our findings suggest that low imidacloprid exposures can restrict reproduction, with potentially severe consequences for the population, notwithstanding the partial recovery in egg production.

Sublethal effects of a pymetrozine-based product (commercial product Chess 50 WP) on life history traits and population growth of one commercialized strain ("Dutch" strain) and two local populations (Bujanovac and Negotin) of the whitefly parasitoid Encarsia formosa Gahan (Hymenoptera: Aphelinidae) were evaluated in laboratory bioassays. All trials were carried out at 27±1°C temperature and under 60±10 % relative humidity and 16/8 h daylight/darkness photoperiod in four replications. Longevity of wasps exposed for 48 h to residues of the pymetrozine insecticide (LC 50 , 280 mg A.I./l) was shorter (by 2.7-3 days) than that of control wasps. Total parasitism of Negotin wasps was significantly reduced (by 8.2 %), as well as total parasitism and adult emergence of the Dutch strain (by 7.3 and 8.2 %, respectively), compared to control wasps. The instantaneous rate of increase (r i) of surviving adult wasps was also significantly reduced (by 6.6, 6.3 and 7.6 % in populations Negotin, Bujanovac and Dutch strain, respectively). Direct treatment of wasps at their pupal stage (LC 50 , 300 mg A.I./l) reduced total parasitism of Negotin wasps (by 8 %), and reduced r i levels, but the reduction was significant only for the Bujanovac (by 6.7 %) and Negotin (by 4.6 %) populations. Juvenile development of the parasitoid in treated pupae was significantly extended (by 0.3-1.1 days), compared to control wasps. The implications of these results on integrated control of the greenhouse whitefly are discussed., U laboratorijskim uslovima, utvrđivani su subletalni efekti preparata na bazi pimetrozina (Chess 50 WP) na parametre životne istorije i populacioni rast preživelih ženki komercijalizovane ("Dutch" rase) i dve lokalne populacije (Bujanovac i Negotin) parazitoida Encarsia formosa Gahan (Hymenoptera: Aphelinidae). Svi ogledi su izvedeni na temperaturi 27±1°C i relativnoj vlažnosti vazduha od 60±10 %, uz fotoperiod 16:8 h, u četiri ponavljanja. U biotestu sa adultima, preparat na bazi pimetrozina, primenjen u srednjim letalnim koncentracijama (280 mg a.s./l) značajno je redukovao dužinu života (za 2,7-3 dana) i preživljavanje ženki iz svih ispitivanih populacija. Rezidualno delovanje pimetrozina smanjilo je ukupni parazitizam osa populacije Negotin i komercijalizovane populacije (za 8,2 i 7,3 %), ukupnu ekloziju adulta komercijalizovane populacije (za 8,2 %), kao i trenutnu stopu rasta sve tri ispitivane populacije (za 6,6, 6,3 i 7,6 %, za Bujanovac, Negotin i "Dutch" populaciju, respektivno). Primenjen direktno na lutke parazitoida (300 mg a.s./l), preparat na bazi pimetrozina je značajno produžio razviće juvenila (za 0,3-1,1 dan) svih ispitivanih populacija, smanjio ukupni parazitizam ženki populacije Negotin (za 8 %) i statistički značajno redukovao trenutnu stopu rasta populacija Bujanovac (6,7 %) i Negotin (4,6 %). Tačna determinacija rizika primene ovog preparata zahteva njegovo dalje testiranje u poljskim uslovima. Razmatrane su mogućnosti praktične primene dobijenih rezultata u okviru integralnog koncepta zaštite biljaka od bele leptiraste vaši.

The use of some systemic insecticides has been banned in Europe because they are toxic to beneficial insects when these feed on nectar. A recent study shows that systemic insecticides can also kill beneficial insects when they feed on honeydew. Honeydew is the sugar-rich excretion of hemipterans and is the most abundant carbohydrate source for beneficial insects such as pollinators and biological control agents in agroecosystems. Here, we investigated whether the toxicity of contaminated honeydew depends on i) the hemipteran species that excretes the honeydew; ii) the active ingredient, and iii) the beneficial insect that feeds on it. HPLC-MS/MS analyses demonstrated that the systemic insecticides pymetrozine and flonicamid, which are commonly used in Integrated Pest Management programs, were present in honeydew excreted by the mealybug Planococcus citri. However, only pymetrozine was detected in honeydew excreted by the whitefly Aleurothixus floccosus. Toxicological studies demonstrated that honeydew excreted by mealybugs feeding on trees treated either with flonicamid or pymetrozine increased the mortality of the hoverfly Sphaerophoria rueppellii, but did not affect the parasitic wasp Anagyrus vladimiri. Honeydew contaminated with flonicamid was more toxic for the hoverfly than that contaminated with pymetrozine. Collectively, our data demonstrate that systemic insecticides commonly used in IPM programs can contaminate honeydew and kill beneficial insects that feed on it, with their toxicity being dependent on the active ingredient and hemipteran species that excretes the honeydew.

In addition to controlling pest organisms, the systemic neurotoxic pesticide fipronil can also have adverse effects on beneficial insects and other non-target organisms. Here, we report on the sublethal effects of fipronil on the farmland butterfly Pieris brassicae. Caterpillars were reared on plants that had been grown from seeds coated with fipronil or on leaf discs topically treated with a range of fipronil dosages (1-32 µg kg-1 on dry mass basis). Females that had developed on fipronil plants laid ca half the number of eggs than females that had developed on control plants. In the bioassay with leaf discs, longevity and lifetime egg production declined with increasing fipronil dosage. Remarkably, exposure to fipronil during larval development primarily affected the adult stage. Chemical analyses of leaf tissues collected from seed-treated plants revealed concentrations of fipronil and its degradation products close to the analytical limit of detection (less than or equal to 1 µg kg-1). The effective dosage was fivefold higher in the leaf-disc than in the whole-plant experiment. In the whole plant, degradation of fipronil to products that are more toxic than fipronil may explain this discrepancy. Neurotoxicity of insecticides at the level of detection decreases the probability of pinpointing insecticides as the causal agent of harmful effects on non-target organisms.

The use of some systemic insecticides has been banned in Europe because they are toxic to beneficial insects when these feed on nectar. A recent study shows that systemic insecticides can also kill beneficial insects when they feed on honeydew. Honeydew is the sugar-rich excretion of hemipterans and is the most abundant carbohydrate source for beneficial insects such as pollinators and biological control agents in agroecosystems. Here, we investigated whether the toxicity of contaminated honeydew depends on i) the hemipteran species that excretes the honeydew; ii) the active ingredient, and iii) the beneficial insect that feeds on it. HPLC-MS/MS analyses demonstrated that the systemic insecticides pymetrozine and flonicamid, which are commonly used in Integrated Pest Management programs, were present in honeydew excreted by the mealybug Planococcus citri. However, only pymetrozine was detected in honeydew excreted by the whitefly Aleurothixus floccosus. Toxicological studies demonstrated that honeydew excreted by mealybugs feeding on trees treated either with flonicamid or pymetrozine increased the mortality of the hoverfly Sphaerophoria rueppellii, but did not affect the parasitic wasp Anagyrus vladimiri. Honeydew contaminated with flonicamid was more toxic for the hoverfly than that contaminated with pymetrozine. Collectively, our data demonstrate that systemic insecticides commonly used in IPM programs can contaminate honeydew and kill beneficial insects that feed on it, with their toxicity being dependent on the active ingredient and hemipteran species that excretes the honeydew. Insecticides recommended in Integrated Pest Management programs reach honeydew and kill beneficial insects that feed on it.

Acute toxicity of a buprofezin-based product (commercial product Elisa 440 SC) to pupae of the whitefly parasitoid Encarsia formosa Gahan (Hymenoptera: Aphelinidae), and its effects on life history traits and population growth in F1 generation of a commercial strain ("Dutch" strain, D) and two local populations from Serbia (Bujanovac, B; Negotin, N) were examined in laboratory bioassays. All trials were carried out at 27±1°C temperature and 60±10% relative humidity, and under 16/8 h daylight/darkness photoperiod in four replications. In an acute toxicity bioassay, tobacco leaves carrying parasitoid pupae (20 pupae per replicate) were treated with a series of buprofezin concentrations covering a 10-90% mortality range, and mortality was calculated based on the number of emerging adults 9 days after treatment. The following LC50 (mg/l) estimates were obtained: 244.2, 281.5 and 199.5 (for B, N and D, respectively). The product based on buprofezin, applied to parasitoid pupae at concentrations within the LC50s and 95% confidence limits (264 mg/l for B and N; 220 mg/l for D), significantly prolonged the duration of juvenile development (2, 1.7 and 2.2 days for B, N and D, respectively, compared to control data). Females from all tested populations that emerged from the treated pupae and were exposed to the residual action of buprofezin lived shorter than control females (B, N and D by 1.5, 0.7 and 1.7 days, respectively). Also, females that emerged from the treated pupae achieved a significantly reduced level of parasitism (B, N and D by 11.7, 17.7 and 17.6 %, respectively), total adult emergence (B, N and D by 11.6, 17.8 and 17.8 %, respectively) and instantaneous rate of increase (B, N and D by 8.2, 6.8 and 12.5 %, respectively), compared to control. More precise determination of risks involved in the use of buprofezin requires its more detailed field testing., Akutna toksičnosti preparata na bazi buprofezina (komercijalni produkt Elisa 440 SC) po stadijum lutke parazitoida Encarsia formosa Gahan (Hymenoptera: Aphelinidae) i efekti na parametre životne istorije i populacioni rast preživelih ženki parazitoida komercijalizovane ("Dutch" rase, D) i dve lokalne populacije iz Srbije (Bujanovac, B; Negotin, N) utvrđivani su u laboratorijskim uslovima. Svi ogledi su izvedeni na temperaturi 27±1°C i relativnoj vlažnosti vazduha od 60±10%, uz fotoperiod 16:8h, u četiri ponavljanja. U biotestu akutne toksičnosti, listovi duvana sa lutkama parazitoida (20 lutki po ponavljanju) tretirani su serijom simetrično raspoređenih koncentracija buprofezina, u rasponu koji pokriva 10-90% smrtnosti, i smrtnost je utvrđivana na osnovu broja eklodiranih adulta iz tretiranih lutki, devet dana nakon tretmana. U testovima akutne toksičnosti dobijene su sledeće srednje letalne koncentracije: 244.2, 281.5 and 199.5 (za B, N i D, respektivno). Preparat na bazi buprofezina, primenjen direktno na lutke parazitoida, u srednjim letalnim koncentracijama (264 mg/l za B i N; 220 mg/l za D), kod svih ispitivanih populacija značajno je umanjio preživljavanje ženki iz tretiranih lutki, produžio dužinu juvenilnog razvića (za 2, 1.7 i 2.2 dana, za B, N i D, respektivno), redukovao ukupni parazitizam ženki (za 11.7, 17.7 i 17.6 % za B, N i D, respektivno), ukupnu pojavu adulta ženki (11.6, 17.8 i 17.8 % za B, N i D, respektivno) i statistički značajno redukovao trenutnu stopu rasta ženki (za 8.2, 6.8 i 12.5 % za B, N i D, respektivno), u odnosu na kontrolu. Tačna determinacija rizika primene ovog preparata, zahteva njegovo dalje testiranje u poljskim uslovima.

Emergent diseases may result in population declines by inducing mortality directly or through sublethal effects on host reproduction. Snake fungal disease (SFD) is an emerging threat to biodiversity, but the sublethal impacts of disease on host fitness are poorly characterized. The cryptic nature of most snakes makes direct assessment of the fitness consequences of SFD challenging. In such contexts, measurement of sex steroids that correlate positively with seasonal reproductive investment may be useful in inferring the scope of disease impacts. To test the hypothesis that SFD is associated with reproductive suppression, we measured testosterone and estradiol in free-ranging pygmy rattlesnakes with varying clinical signs of SFD. We also used real-time PCR to validate the relationship between clinical signs and Ophidiomyces ophiodiicola (Oo) DNA presence on the skin. Infected males had lower testosterone compared to uninfected males during summer spermatogenesis and the fall breeding season. Infected females were less likely to have elevated estradiol compared to uninfected females during spring vitellogenesis. Approximately 85% of individuals with clinical signs were positive for Oo DNA. Our findings are consistent with the hypothesis that coping with SFD comes at a cost to the reproductive success of afflicted individuals, and that seasonal sex steroids may be valuable early indicators of sublethal effects.

Emergent diseases may result in population declines by inducing mortality directly or through sublethal effects on host reproduction. Snake fungal disease (SFD) is an emerging threat to biodiversity, but the sublethal impacts of disease on host fitness are poorly characterized. The cryptic nature of most snakes makes direct assessment of the fitness consequences of SFD challenging. In such contexts, measurement of sex steroids that correlate positively with seasonal reproductive investment may be useful in inferring the scope of disease impacts. To test the hypothesis that SFD is associated with reproductive suppression, we measured testosterone and estradiol in free-ranging pygmy rattlesnakes with varying clinical signs of SFD. We also used real-time PCR to validate the relationship between clinical signs and Ophidiomyces ophiodiicola (Oo) DNA presence on the skin. Infected males had lower testosterone compared to uninfected males during summer spermatogenesis and the fall breeding season. Infected females were less likely to have elevated estradiol compared to uninfected females during spring vitellogenesis. Approximately 85% of individuals with clinical signs were positive for Oo DNA. Our findings are consistent with the hypothesis that coping with SFD comes at a cost to the reproductive success of afflicted individuals, and that seasonal sex steroids may be valuable early indicators of sublethal effects.

Anticoagulant rodenticides have been detected in many species of wildlife worldwide; yet the origins, exposure pathways, and effects of this exposure are not well understood. Furthermore, to accurately characterize the risks from rodenticide use, information is needed on what proportion of populations are being exposed, what proportion of the exposed individuals are affected, and in what ways. The relationship between anticoagulant rodenticide concentrations found in wildlife and the rate of mortality or illness is the subject of much current research. Residue levels observed in liver and whole body analyses vary, and overlap extensively among apparently healthy asymptomatic individuals and sublethal and lethal cases. Results from laboratory studies also show there can be wide variability in lethal and sublethal effects among and within taxonomic groups. Correlating the sublethal and reproductive effects observed in laboratory studies with realistic exposure scenarios and effects in the wild is needed to improve risk assessments. For species with limited numbers/declining populations, a critical question is whether the rodenticide exposure documented in individual animals inhibit population growth or contribute to population declines by lowering survival and reproductive success. This information is essential to the regulatory agencies that must weigh the risks and benefits of rodenticide uses and identify restrictions that are effective in reducing risks to wildlife. A primary objective of this symposium was to facilitate communication between regulators and researchers. Current research on many of these topics was presented, and was followed by discussions on how to improve our understanding of what factors lead to wildlife exposure and improve our ability to assess the effects of exposure on individuals and populations. A collaborative approach will be developed to design studies that provide regulatory and wildlife management agencies with additional science on

Anticoagulant rodenticides have been detected in many species of wildlife worldwide; yet the origins, exposure pathways, and effects of this exposure are not well understood. Furthermore, to accurately characterize the risks from rodenticide use, information is needed on what proportion of populations are being exposed, what proportion of the exposed individuals are affected, and in what ways. The relationship between anticoagulant rodenticide concentrations found in wildlife and the rate of mortality or illness is the subject of much current research. Residue levels observed in liver and whole body analyses vary, and overlap extensively among apparently healthy asymptomatic individuals and sublethal and lethal cases. Results from laboratory studies also show there can be wide variability in lethal and sublethal effects among and within taxonomic groups. Correlating the sublethal and reproductive effects observed in laboratory studies with realistic exposure scenarios and effects in the wild is needed to improve risk assessments. For species with limited numbers/declining populations, a critical question is whether the rodenticide exposure documented in individual animals inhibit population growth or contribute to population declines by lowering survival and reproductive success. This information is essential to the regulatory agencies that must weigh the risks and benefits of rodenticide uses and identify restrictions that are effective in reducing risks to wildlife. A primary objective of this symposium was to facilitate communication between regulators and researchers. Current research on many of these topics was presented, and was followed by discussions on how to improve our understanding of what factors lead to wildlife exposure and improve our ability to assess the effects of exposure on individuals and populations. A collaborative approach will be developed to design studies that provide regulatory and wildlife management agencies with additional science on

Acute toxicity of an imidacloprid-based product (Confidor 200 SL) to pupae of the whitefly parasitoid Encarsia formosa Gahan (Hymenoptera: Aphelinidae), and its effects on life history traits and population growth in F1 generation of the surviving parasitoid females of a commercial strain (“Dutch” strain, D) and two local populations from Serbia (Bujanovac, B; Negotin, N) were examined in laboratory bioassays. All trials were carried out at 27±1°C temperature and 60±10% relative humidity, and under 16/8 h daylight/darkness photoperiod in four replications. In acute toxicity bioassays, tobacco leaves carrying parasitoid pupae were treated with a series of symmetrical concentrations (800, 400, 200, 100, 50 and 25 mg a.i./l) covering a 10-90% mortality range. The product based on imidacloprid, applied directly onto parasitoid pupae at mean lethal concentrations (LC 50) determined in the acute toxicity assays (30 mg/l, 20 mg/l and 25 mg/l, for populations B, N and D, respectively), significantly affected the survival of females developed from the treated pupae, extended the duration of juvenile development (by 1.81, 1.59 and 1.73 days for populations B, N and D, respectively), significantly reduced total parasitism of females D (25.92 %), total female adult emergence in populations B (27.48 %) and D (17.92 %), and significantly reduced the instantaneous rate of increased only of females N (4.23 %). Considering the high acute toxicity of the imidacloprid product to the pupal stage of E. formosa, and significant reductions in life table and population parameters, imidacloprid is not considered compatible for simultaneous use with the parasitoid E. formosa. A more precise assessment of risks involved in the use of that insecticide requires a more detailed testing in the field. The implications of these results for the concept of integrated control of the greenhouse whitefly are discussed., Akutna toksičnosti preparata na bazi imidakloprida (Confidor 200 SL) po stadijum lutke parazitoida Encarsia formosa Gahan (Hymenoptera: Aphelinidae) i efekti na parametre životne istorije i populacioni rast preživelih ženki parazitoida komercijalizovane („Dutch“ rase, D) i dve lokalne populacije iz Srbije (Bujanovac, B; Negotin, N) utvrđivani su u laboratorijskim uslovima. Svi ogledi su izvedeni na temperaturi 27±1°C i relativnoj vlažnosti vazduha od 60±10%, uz fotoperiod 16:8h, u četiri ponavljanja. U biotestu akutne toksičnosti, listovi duvana sa lutkama parazitoida tretirani su serijom simetrično raspoređenih koncentracija (800, 400, 200, 100, 50 i 25 mg a.m./l) u rasponu koji pokriva 10-90% smrtnosti. Preparat na bazi imidakloprida, primenjen direktno na lutke parazitoida, u srednjim letalnim koncentracijama (LC50) dobijenim u testovima akutne toksičnosti (30 mg/l, 20 mg/l i 25 mg/l, za B, N i D, respektivno), značajno je uticao na preživljavanje ženki iz tretiranih lutki, produžio je dužinu juvenilnog razvića (1.81, 1.59 i 1.73 dana, za B, N i D, respektivno), značajno redukovao ukupni parazitizam ženki D (25.92 %), ukupnu pojavu adulta ženki B (27.48 %) i D (17.92 %) i statistički značajno redukovao samo trenutnu stopu rasta ženki N (4.23 %). S obzirom na visoku akutnu toksičnosti preparata na bazi imidakloprida po stadijum lutke parazitoida, i značajne redukcije životnih i populacionih parametara, imidakloprid se ne smatra kompatibilnim za zajedničku primenu sa parazitoidom E. formosa. Tačna determinacija rizika primene ovog preparata, zahteva njegovo dalje testiranje u poljskim uslovima. Razmatrane su mogućnosti praktične primene dobijenih rezultata u okviru integralnog koncepta zaštite biljaka od bele leptiraste vaši.

Akaricidni i subletalni efekti komercijalnih preparata biopesticida na bazi oksimatrina, azadirahtina, spinosada i entomopatogene gljive Beauveria bassiana na običnu grinju-paučinara Tetranychus urticae Koch (Acari: Tetranychidae) ispitivani su u laboratorijskim biotestovima, u cilju kompletiranja profila njihove biološke aktivnosti kao osnove za definisanje održive strategije primene. Biotestovi su izvedeni na temperaturi 27±2°C i relativnoj vlažnosti 50-70% uz fotoperiod svetlo/tama 16h/8h. Biopesticidi su aplicirani prskanjem lisnih isečaka (prečnika 30 mm) ili celih primarnih listova pasulja, postavljenih adaksijalno u Petri sudove, pomoću aparata Potter Tower (2 ml tečnosti, pritisak 100 kPa, vodeni depozit 2,7 mg/cm2). Toksičnost biopesticida za životne stadijume T. urticae ocenjena je izvođenjem biotestova u kojima su jaja, juvenilni stadijumi (larve, protonimfe, ženke deutonimfe) ili odrasle preovipozicione ženke tretirane serijom simetrično raspoređenih koncentracija, a dobijeni podaci obrađeni postupkom probit-analize. Nijedan od ispitivanih biopesticida nije uzrokovao značajnu ovicidnost, već je akaricidni efekat nastao usled rezidualnog delovanja biopesticida na larve ispiljene iz tretiranih jaja. U svim biotestovima direktno tretirane larve bile su najosetljiviji životni stadijum. Direktno tretiranje preovipozicionih ženki preparatima na bazi azadirahtina i B. bassiana uzrokovaloje RO-efekat („run-off“-efekat: napuštanje tretirane površine) kao dominantan u odnosu na smrtnost. Vrednosti LC90 za preparat na bazi oksimatrina bile su znatno niže od koncentracije preporučene za primenu (2 ml/l), dok su kod spinosada bile više od preporučenih koncentracija (60-300 mg/l). Vrednosti LC90 za azadirahtin bile su niže a vrednosti EC90 za RO-efekat ovog biopesticida viša od preporučene koncentracije (50 mg/l a.m.). U biotestovima sa preparatom na bazi B. bassiana sve LC/EC90 vrednosti (osim za LC90 za larve) bile su više od preporučene koncentracije (3 ml/l). Repe, Acaricide and sublethal effects of several commercial biopesticide products based on oxymatrine, azadirachtin, spinosad and the entomopathogenic fungus Beauveria bassiana on the two-spotted spider mite Tetranychus urticae Koch (Acari: Tetranychidae) were examined in laboratory bioassays in order to round off a profile of their biological activity as a basis for defining a sustainable application strategy. Bioassays were performed at 27±2°C temperature, 50-70% relative humidity and 16h/8h light/dark photoperiod. The biopesticides were sprayed on bean leaf discs (30 mm in diameter) or intact leaves positioned adaxially in Petri dishes using a Potter Tower device (2 ml liquid, 100 kPa pressure, 2.7 mg/cm2 water deposit). Toxicity of the biopesticides to different stages of T. urticae mites was assessed in bioassays in which eggs, juvenile stages (larvae, protonymphs, female deutonymphs) or adult preovipositing females were treated with a series of symmetrical concentrations, and the data were processed by probit analysis. None of the investigated biopesticides caused a significant ovicide effect, while acaricide effects resulted from their residual effects on larvae hatched from the treated eggs. In all bioassays, directly treated larvae were found the most sensitive life stage. Direct treatment of preovipositing females with azadirachtin and B. bassiana products caused a run-off effect which was dominant compared to mortality. The LC90 values of the oxymatrine product were significantly lower than its recommended concentration (2 ml/l), while those of spinosad were higher than the recommended concentration (60-300 mg/l). Azadirachtin LC90 values were lower and those of its RO-effect higher than the recommended concentration (50 mg/l a.i.). In B. bassiana bioassays, all LC/EC90 values (except LC90 for larvae) were higher than the recommended concentration (3 ml/l). Repellence and ovipositional deterrence of the biopesticides were assessed in bioassays in which preovipo

Akaricidni i subletalni efekti komercijalnih preparata biopesticida na bazi oksimatrina, azadirahtina, spinosada i entomopatogene gljive Beauveria bassiana na običnu grinju-paučinara Tetranychus urticae Koch (Acari: Tetranychidae) ispitivani su u laboratorijskim biotestovima, u cilju kompletiranja profila njihove biološke aktivnosti kao osnove za definisanje održive strategije primene. Biotestovi su izvedeni na temperaturi 27±2°C i relativnoj vlažnosti 50-70% uz fotoperiod svetlo/tama 16h/8h. Biopesticidi su aplicirani prskanjem lisnih isečaka (prečnika 30 mm) ili celih primarnih listova pasulja, postavljenih adaksijalno u Petri sudove, pomoću aparata Potter Tower (2 ml tečnosti, pritisak 100 kPa, vodeni depozit 2,7 mg/cm2). Toksičnost biopesticida za životne stadijume T. urticae ocenjena je izvođenjem biotestova u kojima su jaja, juvenilni stadijumi (larve, protonimfe, ženke deutonimfe) ili odrasle preovipozicione ženke tretirane serijom simetrično raspoređenih koncentracija, a dobijeni podaci obrađeni postupkom probit-analize. Nijedan od ispitivanih biopesticida nije uzrokovao značajnu ovicidnost, već je akaricidni efekat nastao usled rezidualnog delovanja biopesticida na larve ispiljene iz tretiranih jaja. U svim biotestovima direktno tretirane larve bile su najosetljiviji životni stadijum. Direktno tretiranje preovipozicionih ženki preparatima na bazi azadirahtina i B. bassiana uzrokovaloje RO-efekat („run-off“-efekat: napuštanje tretirane površine) kao dominantan u odnosu na smrtnost. Vrednosti LC90 za preparat na bazi oksimatrina bile su znatno niže od koncentracije preporučene za primenu (2 ml/l), dok su kod spinosada bile više od preporučenih koncentracija (60-300 mg/l). Vrednosti LC90 za azadirahtin bile su niže a vrednosti EC90 za RO-efekat ovog biopesticida viša od preporučene koncentracije (50 mg/l a.m.). U biotestovima sa preparatom na bazi B. bassiana sve LC/EC90 vrednosti (osim za LC90 za larve) bile su više od preporučene koncentracije (3 ml/l). Repe, Acaricide and sublethal effects of several commercial biopesticide products based on oxymatrine, azadirachtin, spinosad and the entomopathogenic fungus Beauveria bassiana on the two-spotted spider mite Tetranychus urticae Koch (Acari: Tetranychidae) were examined in laboratory bioassays in order to round off a profile of their biological activity as a basis for defining a sustainable application strategy. Bioassays were performed at 27±2°C temperature, 50-70% relative humidity and 16h/8h light/dark photoperiod. The biopesticides were sprayed on bean leaf discs (30 mm in diameter) or intact leaves positioned adaxially in Petri dishes using a Potter Tower device (2 ml liquid, 100 kPa pressure, 2.7 mg/cm2 water deposit). Toxicity of the biopesticides to different stages of T. urticae mites was assessed in bioassays in which eggs, juvenile stages (larvae, protonymphs, female deutonymphs) or adult preovipositing females were treated with a series of symmetrical concentrations, and the data were processed by probit analysis. None of the investigated biopesticides caused a significant ovicide effect, while acaricide effects resulted from their residual effects on larvae hatched from the treated eggs. In all bioassays, directly treated larvae were found the most sensitive life stage. Direct treatment of preovipositing females with azadirachtin and B. bassiana products caused a run-off effect which was dominant compared to mortality. The LC90 values of the oxymatrine product were significantly lower than its recommended concentration (2 ml/l), while those of spinosad were higher than the recommended concentration (60-300 mg/l). Azadirachtin LC90 values were lower and those of its RO-effect higher than the recommended concentration (50 mg/l a.i.). In B. bassiana bioassays, all LC/EC90 values (except LC90 for larvae) were higher than the recommended concentration (3 ml/l). Repellence and ovipositional deterrence of the biopesticides were assessed in bioassays in which preovipo

Cartagena coastal zone (W Mediterranean) was chosen for a practical case study to investigate the suitability of an integrated indicator framework for marine monitoring and assessment of chemicals and their effects, which was developed by ICES and OSPAR. Red mullet (Mullus barbatus) and the Mediterranean mussel (Mytilus galloprovincialis) were selected as target species. Concentrations of contaminants in sediment and biota, and contaminant-related biomarkers were analysed. To assess environmental quality in the Cartagena coastal zone with respect to chemical pollution, data were assessed using available assessment criteria, and then integrated for different environmental matrices. A qualitative scoring method was used to rank the overall assessments into selected categories and to evaluate the confidence level of the final integrated assessment. The ICES/OSPAR integrated assessment framework, originally designed for the North Atlantic, was found to be applicable for Mediterranean species and environmental matrices. Further development of assessment criteria of chemical and biological parameters in sediments and target species from the Mediterranean will, however, be required before this framework can be fully applied for determining Good Environmental Status (GES) of the Marine Strategy Framework Directive in these regions.

The application of road deicing salts in northern regions worldwide is changing the chemical environment of freshwater ecosystems. Chloride levels in many lakes, streams, and wetlands exceed the chronic and acute thresholds established by the United States and Canada for the protection of freshwater biota. Few studies have identified the impacts of deicing salts in stream and wetland communities and none have examined impacts in lake communities. We tested how relevant concentrations of road salt (15, 100, 250, 500, and 1000mgCl(-)/L) interacted with experimental communities containing two or three trophic levels (i.e., no fish vs. predatory fish). We hypothesized that road salt and fish would have a negative synergistic effect on zooplankton, which would then induce a trophic cascade. We tested this hypothesis in outdoor mesocosms containing filamentous algae, periphyton, phytoplankton, zooplankton, several macroinvertebrate species, and fish. We found that the presence of fish and high salt had a negative synergistic effect on the zooplankton community, which in turn caused an increase in phytoplankton. Contributing to the magnitude of this trophic cascade was a direct positive effect of high salinity on phytoplankton abundance. Cascading effects were limited with respect to impacts on the benthic food web. Periphyton and snail grazers were unaffected by the salt-induced trophic cascade, but the biomass of filamentous algae decreased as a result of competition with phytoplankton for light or nutrients. We also found direct negative effects of high salinity on the biomass of filamentous algae and amphipods (Hyalella azteca) and the mortality of banded mystery snails (Viviparus georgianus) and fingernail clams (Sphaerium simile). Clam mortality was dependent on the presence of fish, suggesting a non-consumptive interactive effect with salt. Our results indicate that globally increasing concentrations of road salt can alter community structure via both direct and ind

BackgroundAcute intoxication with organophosphorus (OP) cholinesterase inhibitors can trigger convulsions that progress to life-threatening status epilepticus. Survivors face long-term morbidity including mild-to-severe decline in memory. It is posited that neuroinflammation plays a key role in the pathogenesis of OP-induced neuropsychiatric deficits. Rigorous testing of this hypothesis requires preclinical models that recapitulate relevant phenotypic outcomes. Here, we describe a rat model of acute intoxication with the OP diisopropylfluorophosphate (DFP) that exhibits persistent neuroinflammation and cognitive impairment.MethodsNeuroinflammation, neurodegeneration, and cognitive function were compared in adult male Sprague Dawley rats injected with an acutely toxic dose of DFP vs. vehicle controls at multiple time points up to 36 days post-exposure. Neuroinflammation was quantified using immunohistochemical biomarkers of microglia (ionized calcium-binding adapter molecule 1, IBA1) and activated astrocytes (glial fibrillary acidic protein, GFAP) and positron emission tomography (PET) imaging of [11C]-(R)-PK11195, a ligand for the 18-kDa mitochondrial membrane translocator protein (TSPO). FluoroJade-B staining was used to assess neurodegeneration; Pavlovian conditioning, to assess cognitive function.ResultsAnimals exhibited moderate-to-severe seizures within minutes of DFP injection that continued for up to 6 h post-injection. As indicated by IBA1 and GFAP immunoreactivity and by PET imaging of TSPO, acute DFP intoxication triggered neuroinflammation in the hippocampus and cortex during the first 3 days that peaked at 7 days and persisted to 21 days post-exposure in most animals. Neurodegeneration was detected in multiple brain regions from 1 to 14 days post-exposure. All DFP-intoxicated animals exhibited significant deficits in contextual fear conditioning at 9 and 20 days post-exposure compared to vehicle controls. Whole-brain TS

BackgroundAcute intoxication with organophosphorus (OP) cholinesterase inhibitors can trigger convulsions that progress to life-threatening status epilepticus. Survivors face long-term morbidity including mild-to-severe decline in memory. It is posited that neuroinflammation plays a key role in the pathogenesis of OP-induced neuropsychiatric deficits. Rigorous testing of this hypothesis requires preclinical models that recapitulate relevant phenotypic outcomes. Here, we describe a rat model of acute intoxication with the OP diisopropylfluorophosphate (DFP) that exhibits persistent neuroinflammation and cognitive impairment.MethodsNeuroinflammation, neurodegeneration, and cognitive function were compared in adult male Sprague Dawley rats injected with an acutely toxic dose of DFP vs. vehicle controls at multiple time points up to 36 days post-exposure. Neuroinflammation was quantified using immunohistochemical biomarkers of microglia (ionized calcium-binding adapter molecule 1, IBA1) and activated astrocytes (glial fibrillary acidic protein, GFAP) and positron emission tomography (PET) imaging of [11C]-(R)-PK11195, a ligand for the 18-kDa mitochondrial membrane translocator protein (TSPO). FluoroJade-B staining was used to assess neurodegeneration; Pavlovian conditioning, to assess cognitive function.ResultsAnimals exhibited moderate-to-severe seizures within minutes of DFP injection that continued for up to 6 h post-injection. As indicated by IBA1 and GFAP immunoreactivity and by PET imaging of TSPO, acute DFP intoxication triggered neuroinflammation in the hippocampus and cortex during the first 3 days that peaked at 7 days and persisted to 21 days post-exposure in most animals. Neurodegeneration was detected in multiple brain regions from 1 to 14 days post-exposure. All DFP-intoxicated animals exhibited significant deficits in contextual fear conditioning at 9 and 20 days post-exposure compared to vehicle controls. Whole-brain TS

This thesis focuses on a modern analytical method, proteomics, to investigate its use in the field of toxicological research. Proteomics is a high resolution method which separates all proteins present in a sample at a clearly defined state and compares this pattern to another one, under slightly different conditions (e.g. after exposure to a chemical). Protein changes may give rise to or reflect disease/harm of the individual and can be attributed to alterations in body functions/regulation systems. Analysis conditions and different varieties of proteomic methods are explained, and a brief introduction given where proteomics is already applied in toxicology. A specific investigation has been performed with the flame retardant HBCD (i.e. hexabromocyclododecane). It is a compound that accumulates in lipid tissue from where it is only slowly removed. Its mechanism of action is not yet completely understood and sometimes seems to be contradictory. Rats were exposed to HBCD in very low doses for just one week and liver proteins were compared to those of unexposed animals. As HBCD is suggested to disturb the thyroid system, both healthy and hypothyroid rats were investigated, of both genders. In female rats, not in males, some specific liver protein changes were seen in glucose/carbohydrate and lipid metabolism, and also in some stress related proteins. Changes were not dependent on the thyroid function of the females. These results are in line with previous findings that female rats were more susceptible to HBCD than males. In a further step, protein patterns of unexposed animals of both genders were compared, revealing gender-dependent differences that exceeded the effects seen in any of the other comparisons, mainly in the pathways that were also affected by HBCD in females. A previous proteomic study on serum proteins has also shown clear gender-dependent concentration differences in rats. This underlines the importance of performing studies both in female and male i

The scarcity of information on the effects of pesticides on Australian native vertebrates constrains the development of biologically relevant risk assessments in Australia for the registration of insecticides. This thesis investigates the sensitivity of two dasyurid marsupials, Sminthopsis crassicaudata (Gould 1844) and S. macroura (Gould 1845) to an organophosphorous (OP) insecticide, fenitrothion (O,O-dimethyl-O- (3-methyl-4-nitrophenol)-phosphorothioate), a common locust control agent in Australia. The effects of fenitrothion on a suite of physiological measures that affect the ability of animals to survive in free-living conditions (namely, locomotory and thermogenic functions, metabolic performance, body mass, haematocrit and haemoglobin levels as well as plasma and brain cholinesterase activity) are investigated in relation to time since exposure in S. macroura. The concern that endemically old and unique Australian vertebrate fauna might display high sensitivity to pesticides used for locust control provoked examination of the acute oral toxicity of fenitrothion for the fat-tailed dunnart S. crassicaudata and the stripe-faced dunnart, S. macroura in Chapter 2 of this thesis. Using the Up-and-Down method for determining acute oral toxicity, S. crassicaudata and S. macroura were found to have estimated median lethal doses (LD50) of 129 mg kg-1 (95% confidence interval (CI) = 74.2 - 159.0) and 97 mg kg-1 (95% CI = 88.3 - 120.0) respectively. These values are 10 - 14 times lower than the reported LD50 values for a similar-sized eutherian mammal, Mus musculus (L. 1758) (LD50 = 1100 - 1400 mg kg-1) and lower than all other reported mammalian LD50 values. Such wide inter-specific variation in sensitivity to fenitrothion may be a consequence of underlying differences in the metabolic pathway for fenitrothion detoxification in mammals and a possible explanation for the increased toxicity of fenitrothion to dunnarts, as compared with other mammals, is proposed. The une

The scarcity of information on the effects of pesticides on Australian native vertebrates constrains the development of biologically relevant risk assessments in Australia for the registration of insecticides. This thesis investigates the sensitivity of two dasyurid marsupials, Sminthopsis crassicaudata (Gould 1844) and S. macroura (Gould 1845) to an organophosphorous (OP) insecticide, fenitrothion (O,O-dimethyl-O- (3-methyl-4-nitrophenol)-phosphorothioate), a common locust control agent in Australia. The effects of fenitrothion on a suite of physiological measures that affect the ability of animals to survive in free-living conditions (namely, locomotory and thermogenic functions, metabolic performance, body mass, haematocrit and haemoglobin levels as well as plasma and brain cholinesterase activity) are investigated in relation to time since exposure in S. macroura. The concern that endemically old and unique Australian vertebrate fauna might display high sensitivity to pesticides used for locust control provoked examination of the acute oral toxicity of fenitrothion for the fat-tailed dunnart S. crassicaudata and the stripe-faced dunnart, S. macroura in Chapter 2 of this thesis. Using the Up-and-Down method for determining acute oral toxicity, S. crassicaudata and S. macroura were found to have estimated median lethal doses (LD50) of 129 mg kg-1 (95% confidence interval (CI) = 74.2 - 159.0) and 97 mg kg-1 (95% CI = 88.3 - 120.0) respectively. These values are 10 - 14 times lower than the reported LD50 values for a similar-sized eutherian mammal, Mus musculus (L. 1758) (LD50 = 1100 - 1400 mg kg-1) and lower than all other reported mammalian LD50 values. Such wide inter-specific variation in sensitivity to fenitrothion may be a consequence of underlying differences in the metabolic pathway for fenitrothion detoxification in mammals and a possible explanation for the increased toxicity of fenitrothion to dunnarts, as compared with other mammals, is proposed. The une

The scarcity of information on the effects of pesticides on Australian native vertebrates constrains the development of biologically relevant risk assessments in Australia for the registration of insecticides. This thesis investigates the sensitivity of two dasyurid marsupials, Sminthopsis crassicaudata (Gould 1844) and S. macroura (Gould 1845) to an organophosphorous (OP) insecticide, fenitrothion (O,O-dimethyl-O- (3-methyl-4-nitrophenol)-phosphorothioate), a common locust control agent in Australia. The effects of fenitrothion on a suite of physiological measures that affect the ability of animals to survive in free-living conditions (namely, locomotory and thermogenic functions, metabolic performance, body mass, haematocrit and haemoglobin levels as well as plasma and brain cholinesterase activity) are investigated in relation to time since exposure in S. macroura. The concern that endemically old and unique Australian vertebrate fauna might display high sensitivity to pesticides used for locust control provoked examination of the acute oral toxicity of fenitrothion for the fat-tailed dunnart S. crassicaudata and the stripe-faced dunnart, S. macroura in Chapter 2 of this thesis. Using the Up-and-Down method for determining acute oral toxicity, S. crassicaudata and S. macroura were found to have estimated median lethal doses (LD50) of 129 mg kg-1 (95% confidence interval (CI) = 74.2 - 159.0) and 97 mg kg-1 (95% CI = 88.3 - 120.0) respectively. These values are 10 - 14 times lower than the reported LD50 values for a similar-sized eutherian mammal, Mus musculus (L. 1758) (LD50 = 1100 - 1400 mg kg-1) and lower than all other reported mammalian LD50 values. Such wide inter-specific variation in sensitivity to fenitrothion may be a consequence of underlying differences in the metabolic pathway for fenitrothion detoxification in mammals and a possible explanation for the increased toxicity of fenitrothion to dunnarts, as compared with other mammals, is proposed. The une

The ingestion of imidacloprid treated seeds by farmland birds may result in exposure to toxic amounts of this insecticide. Here we report on the effects that the exposure to the recommended application rate and to 20% of that rate may produce on birds feeding on treated seeds. Experimental exposure to imidacloprid treated seeds was performed on red-legged partridges (Alectoris rufa) (n=15 pairs per treatment group: control, 20% or 100% of the recommended application rate) during two periods that corresponded to the autumn (duration of exposure: 25 days) and late winter (10 days) cereal sowing times in Spanish farmlands. We studied effects on the survival, body condition, oxidative stress biomarkers, plasma biochemistry, carotenoid-based coloration, T-cell mediated immune response and reproduction of exposed adult partridges, and on the survival and T-cell immune response of their chicks. The high dose (recommended application rate) killed all partridges, with mortality occurring faster in females than in males. The low dose (20% the recommended application rate) had no effect on mortality, but reduced levels of plasma biochemistry parameters (glucose, magnesium and lactate dehydrogenase), increased blood superoxide dismutase activity, produced changes in carotenoid-based integument coloration, reduced the clutch size, delayed the first egg lay date, increased egg yolk vitamins and carotenoids and depressed T-cell immune response of chicks. Moreover, the analysis of the livers of dead partridges revealed an accumulation of imidacloprid during exposure time. Despite the moratorium on the use of neonicotinoids in the European Union, birds may still be at high risk of poisoning by these pesticides through direct sources of exposure to coated seeds in autumn and winter.

Lethal and sublethal effects of the biopesticide Kingbo (oxymatrine 0.2 % + psoralen 0.4 %) on the two-spotted spider mite (Tetranychus urticae Koch) were investigated in laboratory bioassays. The biopesticide was applied to bean leaf discs or primary leaves by using a Potter spray tower. Acute toxicity tests showed no significant ovicidal action: toxic effect (LC50 = 55.49 mu l/l) was the result of a residual activity against larvae that hatched from the treated eggs. Preovipositional females and female teleiochrysales showed similar susceptibility (LC50 = 52.68 and 59.03 mu l/l, respectively), whereas larvae, protonymphs and female deutonymphs were the most susceptible stages (LC50 = 6.88, 13.03, and 8.80 mu l/l, respectively). In a choice test, females preferred the untreated halves of leaves over the halves treated with 2,000, 1,000, and 500 mu l/l in the first 24 h, and their oviposition in those treatments was significantly greater on the untreated halves after 24 and 48 h, as well as the summed oviposition over 72 h. Viability and reproduction of survivors, as well as population growth, were strongly affected after the treatments of preovipositional females and female teleiochrysales with 100, 50 and 25 mu l/l. On the other hand, sublethal effects on the females that survived treatment at the egg stage or reached adulthood from the eggs laid on the treated surface (treatments with 50 and 25 mu l/l) were significantly weaker. Acaricidal and sublethal effects of the biopesticide Kingbo were discussed as a starting point for further research aimed to improve management of T. urticae populations. Regulatory issues and safety concerns regarding further commercialization of this biopesticide are addressed as well.

Concern that environmental contaminants contribute to global amphibian population declines has prompted extensive experimental investigation, but individual-level experimental results have seldom been translated to population-level processes. We used our research on the effects of mercury (He) on American toads (Bufo americanus) as a model for bridging the gap between individual-level contaminant effects and amphibian population viability. We synthesized the results of previous field and laboratory studies examining effects of Hg throughout the life cycle of B. americanus and constructed a comprehensive demographic population model to evaluate the consequences of Hg exposure on population dynamics. Our model explicitly considered density-dependent larval survival, which is known to be an important driver of amphibian population dynamics, and incorporated two important factors that have seldom been considered in previous amphibian modeling studies: environmental stochasticity and sublethal effects. We demonstrated that decreases in embryonic survival and sublethal effects (c.a., reduced body size) that delay maturation have minor effects on population dynamics, whereas contaminant effects that reduce late-larval or post-metamorphic survival have important population-level consequences. We found that excessive Hg exposure through maternal transfer or larval diet, alone, had minor effects on B. americanus populations. Simultaneous maternal and dietary exposure resulted in reduced population size and a dramatic increase in extinction probability, but explicit prediction of population-level effects was dependent on the strength of larval density dependence. Our results suggest that environmental contaminants can influence amphibian population viability, but that highly integrative approaches are needed to translate individual-level effects to populations.

Concern that environmental contaminants contribute to global amphibian population declines has prompted extensive experimental investigation, but individual-level experimental results have seldom been translated to population-level processes. We used our research on the effects of mercury (He) on American toads (Bufo americanus) as a model for bridging the gap between individual-level contaminant effects and amphibian population viability. We synthesized the results of previous field and laboratory studies examining effects of Hg throughout the life cycle of B. americanus and constructed a comprehensive demographic population model to evaluate the consequences of Hg exposure on population dynamics. Our model explicitly considered density-dependent larval survival, which is known to be an important driver of amphibian population dynamics, and incorporated two important factors that have seldom been considered in previous amphibian modeling studies: environmental stochasticity and sublethal effects. We demonstrated that decreases in embryonic survival and sublethal effects (c.a., reduced body size) that delay maturation have minor effects on population dynamics, whereas contaminant effects that reduce late-larval or post-metamorphic survival have important population-level consequences. We found that excessive Hg exposure through maternal transfer or larval diet, alone, had minor effects on B. americanus populations. Simultaneous maternal and dietary exposure resulted in reduced population size and a dramatic increase in extinction probability, but explicit prediction of population-level effects was dependent on the strength of larval density dependence. Our results suggest that environmental contaminants can influence amphibian population viability, but that highly integrative approaches are needed to translate individual-level effects to populations.