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1.
Sci Rep ; 10(1): 10958, 2020 07 02.
Artigo em Inglês | MEDLINE | ID: mdl-32616737

RESUMO

Road runoff carries a mixture of contaminants that threatens the quality of natural water bodies and the health of aquatic organisms. The use of sedimentation ponds is a nature-based solution for the treatment of road runoff. This study assessed the concentration of polycyclic aromatic hydrocarbons (PAHs) and their alkylated homologues in sediment from seven highway sedimentation ponds and three natural urban ponds. In addition, the study explored the bioaccumulation of PAHs in dragonfly nymphs (Anisoptera). Finally, biota-sediment accumulation factors (BSAFs) were estimated. The results revealed a significant difference in the concentrations of 16 priority PAHs in sediment, with overall higher levels in sedimentation ponds (2,911 µg/kg on average) compared to natural urban ponds (606 µg/kg on average). PAH levels increased substantially once alkylated homologues were considered, with alkylated comprising between 42 and 87% of the total PAH in sediment samples. These results demonstrate the importance of alkylated forms in the environmental assessment of PAHs. The bioaccumulation assessment indicates that dragonfly nymphs bioaccumulate PAHs to a certain degree. It is not clear, however, whether they metabolize PAHs. BSAF results ranged from approx. 0.006 to 10 and indicate that BSAFs can be a powerful tool to determine the functionality of sedimentation ponds.


Assuntos
Alquilantes/química , Monitoramento Ambiental/métodos , Sedimentos Geológicos/análise , Ninfa/metabolismo , Odonatos/metabolismo , Hidrocarbonetos Policíclicos Aromáticos/análise , Poluentes Químicos da Água/análise , Alquilação , Animais , Bioacumulação , Sedimentos Geológicos/química , Ninfa/crescimento & desenvolvimento , Odonatos/crescimento & desenvolvimento , Hidrocarbonetos Policíclicos Aromáticos/química , Poluentes Químicos da Água/química
2.
J Exp Biol ; 222(Pt 22)2019 11 21.
Artigo em Inglês | MEDLINE | ID: mdl-31672724

RESUMO

Amphibiotic dragonflies show a significant increase in hemolymph total CO2 (TCO2) as they transition from breathing water to breathing air. This study examined the hemolymph acid-base status of dragonflies from two families (Aeshnidae and Libellulidae) as they transition from water to air. CO2 solubility (αCO2 ) and the apparent carbonic acid dissociation constant (pK app) were determined in vitro, and pH/bicarbonate concentration ([HCO3 -]) plots were produced by equilibrating hemolymph samples with P CO2  between 0.5 and 5 kPa in custom-built rotating microtonometers. Hemolymph αCO2  varied little between families and across development (mean 0.355±0.005 mmol l-1 kPa-1) while pK app was between 6.23 and 6.27, similar to values determined for grasshopper hemolymph. However, the non-HCO3 - buffer capacity for dragonfly hemolymph was uniformly low relative to that of other insects (3.6-5.4 mmol l-1 pH-1). While aeshnid dragonflies maintained this level as bimodally breathing late-final instars and air-breathing adults, the buffer capacity of bimodally breathing late-final instar Libellula nymphs increased substantially to 9.9 mmol l-1 pH-1 Using the pH/[HCO3 -] plots and in vivo measurements of TCO2 and P CO2  from early-final instar nymphs, it was calculated that the in vivo hemolymph pH was 7.8 for an aeshnid nymph and 7.9 for a libellulid nymph. The pH/[HCO3 -] plots show that the changes in acid-base status experienced by dragonflies across their development are more moderate than those seen in vertebrate amphibians. Whether these differences are due to dragonflies being secondarily aquatic, or arise from intrinsic differences between insect and vertebrate gas exchange and acid-base regulatory mechanisms, remains an open question.


Assuntos
Equilíbrio Ácido-Base , Hemolinfa/química , Odonatos/crescimento & desenvolvimento , Animais , Organismos Aquáticos/fisiologia , Bicarbonatos/análise , Dióxido de Carbono/análise , Dióxido de Carbono/química , Concentração de Íons de Hidrogênio , Ninfa/fisiologia , Odonatos/fisiologia , Água
3.
Sci Total Environ ; 686: 1173-1184, 2019 Oct 10.
Artigo em Inglês | MEDLINE | ID: mdl-31412513

RESUMO

The biocide Bacillus thuringiensis israelensis (Bti) has become the most commonly used larvicide to control mosquitoes in seasonal wetlands. Although Bti is considered non-toxic to most aquatic organisms, the non-biting chironomids show high susceptibilities towards Bti. As chironomids are a key element in wetland food webs, major declines in their abundance could lead to indirect effects that may be passed through aquatic and terrestrial food chains. We conducted two mesocosm experiments to address this hypothesis by assessing direct and indirect effects of Bti-modified availability of macroinvertebrate and zooplankton food resources on the predatory larvae of palmate and smooth newts (Urodelans: Lissotriton helveticus, Lissotriton vulgaris). We examined newt survival rates and dietary composition by means of stable isotope (δ15N and δ13C) analysis in the presence of Bti treatment and a predator (Odonata: Aeshna cyanea). We assessed palmate newts' body size at and time to metamorphosis while developing in Bti treated mesocosms. Chironomid larvae were the most severely affected aquatic invertebrates in all Bti treated food chains and experienced abundance reductions by 50 to 87%. Moreover, stable isotope analysis revealed that chironomids were preferred over other invertebrates and comprised the major part in newts' diet (56%) regardless of their availability. The dragonfly A. cyanea decreased survival of newt larvae by 27% in Bti treated mesocosms showing affected chironomid abundances. Increasing intraguild predation is most likely favored by the Bti-induced reduction of alternative prey such as chironomid larvae. The decreased food availability after Bti treatment led to slightly smaller L. helveticus metamorphs while their developmental time was not affected. Our findings highlight the crucial role of chironomids in the food webs of freshwater ecosystems. We are also emphasizing the importance of reconsidering human-induced indirect effects of mosquito control on valuable wetland ecosystems particularly in the context of worldwide amphibian and insect declines.


Assuntos
Bacillus thuringiensis , Cadeia Alimentar , Controle de Mosquitos , Odonatos/fisiologia , Salamandridae/fisiologia , Áreas Alagadas , Animais , Alemanha , Larva/crescimento & desenvolvimento , Larva/fisiologia , Ninfa/crescimento & desenvolvimento , Ninfa/fisiologia , Odonatos/crescimento & desenvolvimento , Comportamento Predatório , Salamandridae/crescimento & desenvolvimento
4.
Aquat Toxicol ; 211: 38-45, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-30921756

RESUMO

How global warming changes the toxicity of contaminants is a research priority at the intersection of global change biology and ecotoxicology. While many pesticides are more toxic at higher temperatures this is not always detected. We studied whether deviations from this general pattern can be explained by concentration-dependent interaction effects and by testing the interaction against the inappropriate null model. We exposed larvae of the mosquito Culex pipiens to three concentrations of the pesticide chlorpyrifos (absence, low and high) in the absence and presence of 4 °C warming. Both the low and high chlorpyrifos concentration were lethal and generated negative sublethal effects: activity of acetylcholinesterase (AChE) and total fat content decreased, and oxidative damage to lipids increased, yet growth rate increased. Warming was slightly lethal, yet had positive sublethal effects: growth rate, total fat content and metabolic rate increased, and oxidative damage decreased. For four out of seven response variables the independent action model identified the expected synergistic interaction between chlorpyrifos and warming. Notably, for three variables (survival, AChE and fat content) this was strongly dependent on the chlorpyrifos concentration, and for two of these (AChE and fat content) not associated with a significant interaction in the general(ized) linear models. For survival and fat content, warming only potentiated chlorpyrifos (CPF) toxicity at the low CPF concentration, while the opposite was true for AChE. Our results highlight that taking into account concentration-dependence and appropriate null model testing is crucial to improve our understanding of the toxicity of contaminants in a warming world.


Assuntos
Clorpirifos/toxicidade , Aquecimento Global , Modelos Teóricos , Odonatos/efeitos dos fármacos , Praguicidas/toxicidade , Poluentes Químicos da Água/toxicidade , Acetilcolinesterase/metabolismo , Animais , Temperatura Alta , Larva/crescimento & desenvolvimento , Odonatos/enzimologia , Odonatos/crescimento & desenvolvimento
5.
J Insect Sci ; 19(1)2019 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-30753606

RESUMO

As degradation of sensitive habitats like Sphagnum L. (Sphagnales: Sphagnaceae) peatbogs is endangering their invertebrate fauna, artificial peat pools may offer peatbog insect fauna a chance of survival. The entomofauna of seven peat pools in a peatbog and its surrounding natural marginal zone in SE Poland was investigated at the level of species, assemblages and faunistic metrics, indicating the key environmental drivers of the insect distribution and their implications for the biodiversity and potential conservation of these habitats. The species composition, specialists, and insect assemblages of the peat pools were linked with the fauna typical of both peatbogs and dystrophic pools with an open water surface. The most specialized fauna was found in the pools with the largest Sphagnum cover: only tyrphobionts, of all the ecological elements, significantly discriminated the fauna of peat pools and the marginal zone. Sphagnum cover was the key structural factor affecting the distribution of all the insects. Additionally, dragonflies were dependent on pH, beetles on temperature, and caddisflies on dissolved oxygen; however, structural factors-apart from Sphagnum cover-pool perimeter and emergent vegetation cover were predominant. Our results show that appropriate management of the structural factors of peat pools, especially Sphagnum cover, and the provision of different successional stages, can enhance biodiversity and help to maintain a valuable specialist fauna. Even along small environmental gradients and in a homogeneous area, the response of insects is highly differentiated. Dragonflies probably best represent the conservation value of the overall invertebrate fauna of Sphagnum bogs.


Assuntos
Distribuição Animal , Ecossistema , Insetos/fisiologia , Animais , Besouros/crescimento & desenvolvimento , Besouros/fisiologia , Insetos/crescimento & desenvolvimento , Larva/crescimento & desenvolvimento , Larva/fisiologia , Odonatos/crescimento & desenvolvimento , Odonatos/fisiologia , Polônia , Áreas Alagadas
6.
J Insect Physiol ; 114: 23-29, 2019 04.
Artigo em Inglês | MEDLINE | ID: mdl-30716335

RESUMO

Prey species are often non-randomly distributed along predator gradients but according to how they trade off growth against predation risk. The foraging-mediated growth/predation risk trade-off is well established, with increased foraging accelerating growth but also increasing predator induced mortality. While adaptations in digestive physiology may partly modify the relationship between foraging and growth in response to predation risk, studies exploring the impact of digestive physiology on growth in prey subjected to predation risk are still scarce. Larvae of the dragonfly genus Leucorrhinia segregate at the species level between lakes either being dominated by predatory fish (fish-lakes) or predatory invertebrates (dragonfly-lakes). Predators of these two lake types differ dramatically in their hunting style like searching and pursuing mode causing different selection pressure on prey traits including foraging. In a laboratory experiment we estimated growth rate, digestive physiology (ingested food, growth efficiency, assimilation efficiency, conversion efficiency) and metabolic rate (oxygen consumption) in the presence and absence of predator cues. Whereas fish-lake and dragonfly-lake Leucorrhinia species did not differ in growth rate, they evolved different pathways of digestive physiology to achieve similar growth rate. Because fish-lake species expressed a higher metabolic rate than dragonfly-lake species, we assume energy to be differently allocated and used for metabolic demands between species of both predator environments. Further, growth rate, but not digestive physiology was plastic in response to the presence of predator cues. Our results highlight the impact of digestive physiology in shaping the foraging-mediated growth/predation risk trade-off, with digestive physiology contributing to species distribution patterns along predator gradients.


Assuntos
Adaptação Biológica , Metabolismo Basal , Digestão , Odonatos/crescimento & desenvolvimento , Comportamento Predatório , Animais , Evolução Biológica , Ecossistema , Peixes , Larva/crescimento & desenvolvimento , Consumo de Oxigênio , Seleção Genética
7.
Sci Total Environ ; 662: 655-661, 2019 Apr 20.
Artigo em Inglês | MEDLINE | ID: mdl-30703723

RESUMO

Although pharmaceuticals are recognized as a major threat to aquatic ecosystems worldwide, little is known about their ecological effect on aquatic biota and ecosystems. Drug-induced behaviour changes could have a substantial impact on consumer-resource interactions influencing stability of the community and ecosystem. We combined laboratory experiments and functional response modelling to investigate effects of real wastewater treatment plant (WWTP) effluent, as well as environmentally relevant concentrations of the antidepressants citalopram and opioid pain medication tramadol, on trophic interactions. Our biological system consisted of dragonfly Aeshna cyanea larvae as predator of common carp Cyprinus carpio fry. Exposure to WWTP effluent significantly increased A. cyanea maximum feeding rate, while those parameters in tramadol and citalopram-exposed larvae were significantly lower from unexposed control group. This suggested the potential of all tested pollutants to have an effect on consumer-resource equilibrium in aquatic ecosystems. While WWTP effluent strengthened interaction strength (IS) of consumer-resource interaction dynamics making the food web more vulnerable to fluctuation and destabilization, tramadol and citalopram could inhibit the potential oscillations of the consumer-resource system by weakening the IS. Similar studies to reveal the potential of pervasive pharmaceuticals to change of consumer-resource interactions dynamics are needed, especially when real WWTP effluent consisting of mixture of various pharmaceuticals displayed very different effect from single compounds tested.


Assuntos
Aprendizagem da Esquiva/efeitos dos fármacos , Carpas/fisiologia , Citalopram/efeitos adversos , Odonatos/fisiologia , Comportamento Predatório/efeitos dos fármacos , Tramadol/efeitos adversos , Poluentes Químicos da Água/efeitos adversos , Animais , Cadeia Alimentar , Modelos Biológicos , Ninfa/efeitos dos fármacos , Ninfa/crescimento & desenvolvimento , Ninfa/fisiologia , Odonatos/efeitos dos fármacos , Odonatos/crescimento & desenvolvimento , Inibidores de Captação de Serotonina/efeitos adversos , Inibidores da Recaptação de Serotonina e Norepinefrina/efeitos adversos , Águas Residuárias/análise
8.
Heredity (Edinb) ; 122(6): 893-905, 2019 06.
Artigo em Inglês | MEDLINE | ID: mdl-30542146

RESUMO

Although low levels of genetic structure are expected in highly widespread species, geographical and/or ecological factors can limit species distributions and promote population structure and morphological differentiation. In order to determine the effects of geographical isolation on population genetic structure and wing morphology, 281 individuals of the cosmopolitan odonate Pantala flavescens were collected from four continental (Central and South America) and five insular sites (Polynesian islands and the Maldives). COI sequences and eight microsatellite loci were used to characterize genetic diversity and genetic structure between and within locations. Linear and geometric morphometry were used to evaluate differences in the size and shape of wings. Genetic analysis showed a global genetic difference between the continental and insular sites. American locations did not show genetic structure, even in locations separated by a distance of 5000 km. Easter Island showed the lowest values of genetic diversity (mainly mitochondrial diversity) and the highest values of genetic differences compared to other insular and continental sites. Individuals from Easter Island showed smaller forewings, a different abdomen length to thorax length ratio, and a different configuration of anal loop in the hindwings. Thus, the greater isolation, smaller area, and young geological age seem to have determined the genetic and morphological differences in P. flavescens of Easter Island, where selection could promote a loss of migratory behavior and may improve other life history traits, such as reproduction. This work provides new insight into how microevolutionary processes operate in isolated populations of cosmopolitan species.


Assuntos
Odonatos/anatomia & histologia , Odonatos/genética , Animais , Variação Genética , Genética Populacional , Ilhas , Repetições de Microssatélites , Odonatos/crescimento & desenvolvimento , Filogenia , América do Sul
9.
Sci Total Environ ; 648: 1257-1262, 2019 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-30340271

RESUMO

Aquatic systems receive a wide range of pharmaceuticals that may have adverse impacts on aquatic wildlife. Among these pharmaceuticals, antihistamines are commonly found, and these substances have the potential to influence the physiology of aquatic invertebrates. Previous studies have focused on how antihistamines may affect behaviours of aquatic invertebrates, but these studies probably do not capture the full consequences of antihistamine exposure, as traditional recording techniques do not capture important animal movements occurring at the scale of milliseconds, such as prey escape responses. In this study, we investigated if antihistamine exposure can impact escape responses in aquatic insect, by exposing damselfly (Coenagrion hastulatum) larvae to two environmentally relevant concentrations (0.1 and 1 µg L-1) of diphenhydramine. Importantly, we used a high-speed imaging approach that with high-time resolution captures details of escape responses and, thus, potential impacts of diphenhydramine on these behaviours. Our results show overall weak effects of antihistamine exposure on the escape behaviours of damselfly larvae. However, at stage 2 of the C-escape response, we found a significant increase in turning angle, which corresponds to a reduced swimming velocity, indicating a reduced success at evading a predator attack. Thus, we show that low concentrations of an antihistamine may affect behaviours strongly related to fitness of aquatic insect prey - effects that would have been overlooked using traditional recording techniques. Hence, to understand the full consequences of pharmaceutical contamination on aquatic wildlife, high-speed imaging should be incorporated into future environmental risk assessments.


Assuntos
Difenidramina/análise , Reação de Fuga/efeitos dos fármacos , Antagonistas dos Receptores Histamínicos H1/análise , Odonatos/efeitos dos fármacos , Poluentes Químicos da Água/efeitos adversos , Animais , Relação Dose-Resposta a Droga , Larva/efeitos dos fármacos , Odonatos/crescimento & desenvolvimento , Distribuição Aleatória
10.
J Insect Sci ; 18(5)2018 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-30312460

RESUMO

Agricultural runoff containing herbicide is known to have adverse effects on freshwater organisms. Aquatic insects are particularly susceptible, and herbicide runoff has the potential to affect immunity in this group. Here we examined the effect of ecologically relevant levels of atrazine, an herbicide commonly used in the United States, on immune function in larvae of the blue dasher dragonfly (Odonata: Libelluludae, Pachydiplax longipennis Burmeister 1839) during a long-term exposure at ecologically relevant concentrations. Larvae were exposed to concentrations of 0, 1, 5, and 10 ppb atrazine for 3 or 6 wk. Hemocyte counts, hemolymph phenyloxidase (PO) activity, cuticular PO, and gut PO were measured at the end of each trial period as indicators of immune system strength. Atrazine concentration had a significant effect on hemocyte counts after controlling for larval size. There was a significant interaction between time and concentration for hemolymph PO, cuticular PO, and a marginal interaction for gut PO. The effect of atrazine on the measured immune parameters was often nonmonotonic, with larger effects observed at intermediate concentrations. Therefore, atrazine affects both hemocyte numbers and PO activity over time in P. longipennis, and the changed immune function demonstrated in this study is likely to modify susceptibility to pathogens, alter wound healing, and may decrease available energy for growth and metamorphosis.


Assuntos
Atrazina/efeitos adversos , Herbicidas/efeitos adversos , Imunidade Inata/efeitos dos fármacos , Odonatos/efeitos dos fármacos , Poluentes Químicos da Água/efeitos adversos , Animais , Larva/efeitos dos fármacos , Larva/crescimento & desenvolvimento , Larva/imunologia , Metamorfose Biológica/efeitos dos fármacos , Odonatos/crescimento & desenvolvimento , Odonatos/imunologia , Fatores de Tempo
11.
Environ Sci Pollut Res Int ; 25(35): 35352-35364, 2018 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-30343370

RESUMO

Neonicotinoids and fipronil are the most widely used insecticides in the world. Previous studies showed that these compounds have high toxicity to a wide taxonomic range of non-target invertebrates. In rice cultivation, they are frequently used for nursery-box treatment of rice seedlings. The use of fipronil and neonicotinoid imidacloprid is suspected to be the main cause of population declines of red dragonflies, in particular Sympetrum frequens, because they have high lethal toxicity to dragonfly nymphs and the timing of the insecticides' introduction in Japan (i.e., the late 1990s) overlapped with the sharp population declines. However, a causal link between application of these insecticides and population declines of the dragonflies remains unclear. Therefore, we estimated the amount of the insecticides applied for nursery-box treatment of rice seedlings and analyzed currently available information to evaluate the causality between fipronil and imidacloprid usage and population decline of S. frequens using Hill's causality criteria. Based on our scoring of Hill's nine criteria, the strongest lines of evidence were strength, plausibility, and coherence, whereas the weakest were temporality and biological gradient. We conclude that the use of these insecticides, particularly fipronil, was a major cause of the declines of S. frequens in Japan in the 1990s, with a high degree of certainty. The existing information and our analyses, however, do not allow us to exclude the possibility that some agronomic practices (e.g., midsummer drainage or crop rotation) that can severely limit the survival of aquatic nymphs also played a role in the dragonfly's decline.


Assuntos
Conservação dos Recursos Naturais/métodos , Monitoramento Ambiental/métodos , Inseticidas/toxicidade , Neonicotinoides/toxicidade , Nitrocompostos/toxicidade , Odonatos/efeitos dos fármacos , Pirazóis/toxicidade , Animais , Ecotoxicologia , Inseticidas/análise , Japão , Neonicotinoides/análise , Nitrocompostos/análise , Odonatos/crescimento & desenvolvimento , Oryza/crescimento & desenvolvimento , Dinâmica Populacional , Pirazóis/análise , Estações do Ano
12.
Proc Biol Sci ; 285(1883)2018 07 25.
Artigo em Inglês | MEDLINE | ID: mdl-30051862

RESUMO

Biologists now recognize that ecology can drive evolution, and that evolution in turn produces ecological patterns. I extend this thinking to include longer time scales, suggesting that macroevolutionary transitions can create phenotypic differences among species, which then have predictable impacts on species interactions, community assembly and ecosystem functioning. Repeated speciation can exacerbate these patterns by creating communities with similar phenotypes and hence ecological impacts. Here, I use several experiments to test these ideas in dragonfly larvae that occupy ponds with fish, ponds without fish, or both. I show that macroevolutionary transitions between habitats cause fishless pond species to be more active relative to fish pond specialists, reducing prey abundance, shifting prey community composition and creating stronger trophic cascades. These effects scale up to the community level with predictable consequences for ecosystem multi-functioning. I suggest that macroevolutionary history can have predictable impacts on phenotypic traits, with consequences for interacting species and ecosystems.


Assuntos
Evolução Biológica , Cadeia Alimentar , Odonatos/fisiologia , Comportamento Predatório , Animais , Peixes , Larva/crescimento & desenvolvimento , Larva/fisiologia , Odonatos/crescimento & desenvolvimento , Tanques , Especificidade da Espécie
13.
J Exp Biol ; 221(Pt 15)2018 08 03.
Artigo em Inglês | MEDLINE | ID: mdl-29950450

RESUMO

Dragonflies (Odonata, Anisoptera) are amphibiotic; the nymph is aquatic and breathes water using a rectal gill before metamorphosing into the winged adult, which breathes air through spiracles. While the evolutionary and developmental transition from water breathing to air breathing is known to be associated with a dramatic rise in internal CO2 levels, the changes in blood-gas composition experienced by amphibiotic insects, which represent an ancestral air-to-water transition, are unknown. This study measured total CO2 (TCO2) in hemolymph collected from aquatic nymphs and air-breathing adults of Anax junius, Aeshna multicolor (Aeshnidae), Libellula quadrimaculata and Libellulaforensis (Libellulidae). Hemolymph PCO2  was also measured in vivo in both aeshnid nymphs and marbled crayfish (Procambarus fallax. f. virginalis) using a novel fiber-optic CO2 sensor. The hemolymph TCO2 of the pre- and early-final instar nymphs was found to be significantly lower than that of the air-breathing adults. However, the TCO2 of the late-final instar aeshnid nymphs was not significantly different from that of the air-breathing adults, despite the late-final nymphs still breathing water. TCO2 and PCO2  were also significantly higher in the hemolymph of early-final aeshnid nymphs compared with values for the water-breathing crayfish. Thus, while dragonfly nymphs show an increase in internal CO2 as they transition from water to air, from an evolutionary standpoint, the nymph's ability to breathe water is associated with a comparatively minor decrease in hemolymph TCO2 relative to that of the air-breathing adult.


Assuntos
Dióxido de Carbono/análise , Hemolinfa/química , Odonatos/crescimento & desenvolvimento , Odonatos/fisiologia , Animais , Organismos Aquáticos/fisiologia , Astacoidea/fisiologia , Ninfa/fisiologia , Água
14.
Environ Toxicol Chem ; 37(9): 2401-2412, 2018 09.
Artigo em Inglês | MEDLINE | ID: mdl-29877579

RESUMO

Seasonal aquatic insect emergence represents a critical subsidy link between aquatic and terrestrial ecosystems. Early and late instar larvae developing in wetlands near neonicotinoid-treated cropland can be at risk of chronic insecticide exposure. In the present study, an in situ wetland limnocorral experiment compared emergent insect community responses to imidacloprid, clothianidin, and thiamethoxam. Twenty-one limnocorrals were dosed weekly for 9 wk to target peak nominal doses of 0.0, 0.05, or 0.5 µg/L, followed by a 6-wk recovery period. Thirty-nine aquatic insect taxa were recorded but 11 taxa groups made up 97% of the community composition. Principal response curves (PRCs) indicated that during the dosing period, community composition among the treatments resembled the controls. During the 6-wk recovery period, significant deviance was observed in the high imidacloprid treatment with similar trends in the clothianidin treatment, suggesting that community effects from neonicotinoid exposure can be delayed. Non-biting midges (Diptera: Chironomidae) and damselflies (Odonata: Zygoptera) emerged 18 to 25 d earlier than controls in the imidacloprid and clothianidin neonicotinoid treatments, with no effects from thiamethoxam treatments. These data suggest that phenology and subtle community effects can occur at measured neonicotinoid concentrations of 0.045 (imidacloprid) and 0.038 µg/L (clothianidin) under chronic repeated exposure conditions. Synchronization and community dynamics are critical to aquatic insects and consumers; thus, neonicotinoids may have broad implications for wetland ecosystem function. Environ Toxicol Chem 2018;37:2401-2412. © 2018 SETAC.


Assuntos
Chironomidae/efeitos dos fármacos , Inseticidas/toxicidade , Neonicotinoides/toxicidade , Odonatos/efeitos dos fármacos , Poluentes Químicos da Água/toxicidade , Áreas Alagadas , Animais , Chironomidae/crescimento & desenvolvimento , Desenho de Equipamento , Inseticidas/análise , Larva/efeitos dos fármacos , Modelos Teóricos , Neonicotinoides/análise , Odonatos/crescimento & desenvolvimento , Especificidade da Espécie , Poluentes Químicos da Água/análise
15.
Biol Lett ; 14(5)2018 05.
Artigo em Inglês | MEDLINE | ID: mdl-29720445

RESUMO

Laboratory studies indicate global warming may cause changes in locomotor performance directly relevant for fitness and dispersal. Yet, this remains to be tested under seminatural settings, and the connection with warming-induced alterations in the underlying traits has been rarely studied. In an outdoor mesocosm experiment with the damselfly Ischnura elegans, 4°C warming in the larval stage decreased the flight muscle mass, which correlated with a lower flight endurance. Warming did not affect body mass, size or wing morphology. This illustrates how carry-over effects of warming under seminatural conditions during early development bridge metamorphosis and negatively impact locomotor performance through changes in a key flight-related trait.


Assuntos
Voo Animal/fisiologia , Odonatos/crescimento & desenvolvimento , Temperatura , Animais , Feminino , Larva/fisiologia , Masculino , Metamorfose Biológica , Desenvolvimento Muscular/fisiologia , Odonatos/fisiologia , Asas de Animais/anatomia & histologia
16.
Zoology (Jena) ; 127: 106-113, 2018 04.
Artigo em Inglês | MEDLINE | ID: mdl-29588083

RESUMO

A dragonfly larva migrates from the water to the shore, perches on a plant stem and grasps it with strongly flexed legs. Adult legs inside the larval exoskeleton fit to the larval legs joint-to-joint. The adult emerges with stretched legs. During the molt, an imaginal leg must follow all the angles in exuvial joints. In turn, larval apodemes are withdrawn from imaginal legs. We visualized transient shapes of the imaginal legs by the instant fixation of insects at different moments of the molt, photographed isolated exuvial legs with the imaginal legs inside and then removed the exuvial sheath. Instant shapes of the imaginal tibia show sharp intrapodomere bends copying the angle in the larval femoro-tibial joint. The site of bending shifts distad during the molt. This is possible if the imaginal leg is pliable. The same problem of leg squeezing is also common in hemimetabolous insects as well as in other arthropods, whereas holometabolous insects overcome problems of a tight confinement either by using leg pliability in other ways but not squeezing (cyclorrhaphan flies, mosquitoes) or by pulling hardened legs out without change of their pupal zigzag configuration (moths, ants, honey bees). The pupal legs are not intended to grasp any external substrate.


Assuntos
Muda , Odonatos/crescimento & desenvolvimento , Animais , Fenômenos Biomecânicos , Extremidades/fisiologia , Feminino , Larva , Masculino , Muda/fisiologia , Odonatos/fisiologia
17.
Ecotoxicology ; 27(7): 794-802, 2018 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-29313302

RESUMO

Insecticides usually present in low concentrations in streams are known to impair behaviour and development of non-target freshwater invertebrates. Moreover, there is growing awareness that the presence of natural stressors, such as predation risk may magnify the negative effects of pesticides. This is because perception of predation risk can by itself lead to changes on behaviour and physiology of prey species. To evaluate the potential combined effects of both stressors on freshwater detritivores we studied the behavioural and developmental responses of Chironomus riparius to chlorantraniliprole (CAP) exposure under predation risk. Also, we tested whether the presence of a shredder species would alter collector responses under stress. Trials were conducted using a simplified trophic chain: Alnus glutinosa leaves as food resource, the shredder Sericostoma vittatum and the collector C. riparius. CAP toxicity was thus tested under two conditions, presence/absence of the dragonfly predator Cordulegaster boltonii. CAP exposure decreased leaf decomposition. Despite the lack of significance for interactive effects, predation risk marginally modified shredder effect on leaf decomposition, decreasing this ecosystem process. Shredders presence increased leaf decomposition, but impaired chironomids performance, suggesting interspecific competition rather than facilitation. C. riparius growth rate was decreased independently by CAP exposure, presence of predator and shredder species. A marginal interaction between CAP and predation risk was observed regarding chironomids development. To better understand the effects of chemical pollution to natural freshwater populations, natural stressors and species interactions must be taken into consideration, since both vertical and horizontal species interactions play their role on response to stress.


Assuntos
Cadeia Alimentar , Insetos/fisiologia , Inseticidas/toxicidade , Comportamento Predatório , ortoaminobenzoatos/toxicidade , Alnus , Animais , Chironomidae/efeitos dos fármacos , Chironomidae/crescimento & desenvolvimento , Chironomidae/fisiologia , Comportamento Alimentar/efeitos dos fármacos , Insetos/efeitos dos fármacos , Insetos/crescimento & desenvolvimento , Larva/efeitos dos fármacos , Larva/crescimento & desenvolvimento , Larva/fisiologia , Ninfa/efeitos dos fármacos , Ninfa/crescimento & desenvolvimento , Ninfa/fisiologia , Odonatos/crescimento & desenvolvimento , Odonatos/fisiologia , Folhas de Planta
18.
Arthropod Struct Dev ; 47(1): 36-44, 2018 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-29191794

RESUMO

The larval antennal sensilla of two Zygoptera species, Calopteryx haemorroidalis (Calopterygidae) and Ischnura elegans (Coenagrionidae) are investigated with SEM and TEM. These two species have different antennae (geniculate, setaceous) and live in different environments (lotic, lentic waters). Notwithstanding this, similarities in the kind and distribution of sensilla are outlined: in both species the majority of sensilla types is located on the apical portion of the antenna, namely a composed coeloconic sensillum (possible chemoreceptor), two other coeloconic sensilla (possible thermo-hygroreceptors) and an apical seta (direct contact mechanoreceptor). Other mechanoreceptors, such as filiform hairs sensitive to movements of the surrounding medium or bristles positioned to sense the movements of the flagellar segments, are present on the antenna. Similarities in the antennal sensilla types and distribution are observed also with other dragonfly species, such as Onychogomphus forcipatus and Libellula depressa. A peculiar structure with an internal organization similar to that of a gland is observed in the apical antenna of C. haemorroidalis and I. elegans and it is present also in O. forcipatus and L. depressa. The possible function of this structure is at the moment unknown but deserves further investigations owing to its widespread presence in Odonata larvae.


Assuntos
Antenas de Artrópodes/ultraestrutura , Células Quimiorreceptoras/ultraestrutura , Ecossistema , Mecanorreceptores/ultraestrutura , Odonatos/ultraestrutura , Animais , Larva/ultraestrutura , Microscopia Eletrônica de Varredura , Microscopia Eletrônica de Transmissão , Odonatos/crescimento & desenvolvimento , Tanques , Rios
19.
Biol Lett ; 14(12): 20180741, 2018 12 21.
Artigo em Inglês | MEDLINE | ID: mdl-30958242

RESUMO

Insect migration is globally ubiquitous and can involve continental-scale movements and complex life histories. Apart from select species of migratory moths and butterflies, little is known about the structure of the annual cycle for migratory insects. Using stable-hydrogen isotope analysis of 852 wing samples from eight countries spanning 140 years, combined with 21 years of citizen science data, we determined the full annual cycle of a large migratory dragonfly, the common green darner ( Anax junius). We demonstrate that darners undertake complex long-distance annual migrations governed largely by temperature that involve at least three generations. In spring, the first generation makes a long-distance northbound movement (further than 650 km) from southern to northern range limits, lays eggs and dies. A second generation emerges and returns south (further than 680 km), where they lay eggs and die. Finally, a third resident generation emerges, reproducing locally and giving rise to the cohort that migrates north the following spring. Since migration timing and nymph development are highly dependent on temperature, continued climate change could lead to fundamental changes in the biology for this and similar migratory insects.


Assuntos
Migração Animal , Estágios do Ciclo de Vida , Odonatos/fisiologia , Animais , Hidrogênio , Isótopos , América do Norte , Odonatos/crescimento & desenvolvimento , Estações do Ano
20.
BMC Ecol ; 17(1): 37, 2017 Dec 12.
Artigo em Inglês | MEDLINE | ID: mdl-29228938

RESUMO

BACKGROUND: Invasive ecosystem engineers can facilitate their invasions by modifying the physical environment to improve their own performance, but this positive feedback process has rarely been tested empirically except in sessile organisms. The invasive crayfish Procambarus clarkii is an ecosystem engineer that destroys aquatic macrophytes, which provide a physical refuge for animal prey, and this destruction is likely to enhance vulnerability to predators. Using two series of mesocosm experiments, we tested the hypothesis that the invasive crayfish increases its feeding efficiency on animal prey by reducing submerged macrophytes, thus increasing its individual growth rate in a positive density-dependent manner. RESULTS: In the first experiment, increasing crayfish density reduced both macrophytes and animal prey (dragonfly and chironomid larvae) and, importantly, increased the growth rate of individual crayfish, in accordance with our expectation. In the second experiment, we used artificial macrophytes to clarify whether the physical architecture of macrophytes itself protects animal prey and limits crayfish growth rate. Increasing the artificial macrophyte quantity not only increased the survival of animal prey, but also retarded the crayfish growth rate. CONCLUSIONS: We conclude that macrophytes strengthen bottom-up control of crayfish, but this effect can be relaxed by increasing the density of crayfish via reduction in macrophytes. This positive feedback process may explain the crayfish outbreaks and regime shifts occasionally observed in invaded freshwater ecosystems.


Assuntos
Astacoidea/fisiologia , Ecossistema , Cadeia Alimentar , Espécies Introduzidas , Animais , Astacoidea/crescimento & desenvolvimento , Chironomidae/crescimento & desenvolvimento , Comportamento Alimentar , Água Doce , Larva/crescimento & desenvolvimento , Odonatos/crescimento & desenvolvimento , Desenvolvimento Vegetal , Densidade Demográfica
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