Effects of riparian vegetation removal on body size and wing fluctuating asymmetry (FA) of Argia ... more Effects of riparian vegetation removal on body size and wing fluctuating asymmetry (FA) of Argia tinctipennis Selys (Odonata: Coenagrionidae) were studied in the River Suiá-Miçú basin, which is part of the Xingu basin in Brazilian Amazonia. A total of 70 specimens (n = 33 from preserved and n = 37 from degraded areas) was measured. Five wing measures of each wing (totalizing ten measured characters) were taken. Preserved and degraded points presented non-overlapped variations of a Habitat Integrity Index, supporting the environmental differentiation between these two categories. FA increases in degraded areas approximately four times for the width between the nodus and proximal portion of the pterostigma of forewings (FW), two times for the width of the wing in the region of nodus of FW, and approximately 1.7 times for the number of postnodal cells of FW. The increase is almost five times for the width between the nodus and the proximal portion of the pterostigma of hind wings (HW), three times for the number of postnodal cells of HW, and approximately 1.6 times the width between quadrangle and nodus of HW. Individuals of preserved sites were nearly 3.3% larger than for degraded sites, based on mean hind wing length. Our results supports that the development of A. tinctipennis in degraded areas is affected by riparian vegetation removal and may reflect in wing FA variations. Consequently, these FA measures may be a useful tool for bioassessment using Odonata insects as a model.
Effect of the abiotic factors on Brachymetra albinervis albinervis (Heteroptera: Gerridae). We an... more Effect of the abiotic factors on Brachymetra albinervis albinervis (Heteroptera: Gerridae). We analyzed the influence of abiotic factors, longitudinal and temporal distribution on the abundance of Brachymetra albinervis albinervis Amyot & Serville, 1843. Three sites of Cerrado stream were assessed: headwater, intermediary and river mouth, monthly for a year (June 2011 to May 2012). At each site, the following abiotic variables were monthly measured in a linear 100 meters transect: dissolved oxygen, water temperature, pH, electrical conductivity, width and depth of the stream. Were collected 111 specimens. The river mouth presented lower abundance when compared with others sites (F (2,9) = 13.721, p = 0.001). The periods of the year (rain, ebb, dry or early rains), there was no differences in the abundance. Thus, the abundance of B. a. albinervis analyzed for one year showed variation only in the streams longitudinal distribution, which was attributed to the effect of environmental changes in the river mouth, where presented lower abundance and less environmental integrity. These results contribute to the ecological knowledge of this species and discusses the change in the occurrence and abundance this species due to alteration in aquatic environments. RESUMO. Analisou-se a influência de fatores abióticos, distribuição longitudinal e temporal sobre a abundância de Brachymetra albinervis albinervis Amyot & Serville, 1843. Foram avaliados três sítios de um riacho de Cerrado: nascente, intermediário e foz, mensalmente durante um ano (junho de 2011 a maio de 2012). As variáveis abióticas aferidas foram: oxigênio dissolvido, temperatura da água, pH, condutividade elétrica, largura e profundidade do riacho. Em cada sítio, mensalmente coletou-se em transecção de 100 m lineares. Foram coletados 111 espécimes. A foz apresentou menor abundância quando comparada aos outros locais (F (2, 9) 13,721, p = 0,001). A abundância não variou entre os períodos do ano (chuva, vazante, seca ou início da chuva). Assim, a alteração na abundância de B. a. albinervis analisada ao longo de um ano foi influenciada pelos trechos do córrego, e essa variação foi atribuída a alterações ambientais no sítio foz que apresentou menor abundância e consequentemente é o que apresenta menor integridade ambiental. Esses resultados contribuem para o conhecimento ecológico dessa espécie e discute sobre a mudança da ocorrência da espécie em função da alteração dos ambientes aquáticos.
The ocurrence of males, gamic and ambiohasic females of the greenbug Schizaphis graminum (Rondani... more The ocurrence of males, gamic and ambiohasic females of the greenbug Schizaphis graminum (Rondani, 1852) among parthenogenetics reared on Sorghum bicolor (Linnaeus) Moench, in Ribeirão Preto (São Paulo, Brazil), from 1980 through 1983, follows an annual cycle. They appear from April through June, when the photoperiod has about 11 hours of daily photophase. Despite the low number these findings support the potential for holocycle, triggered by variable abiotic factors in this region with mild winters.
Structural properties of aquatic habitats are the basis of several theories produced to explain t... more Structural properties of aquatic habitats are the basis of several theories produced to explain the functioning of aquatic environments. We predicted a longitudinal change of ecosystem properties along the river, and also that potamal areas of the river are similar to lakes. In rivers with periodic floods we also expect a high degree of similarity due to increased environmental similarity and increase dispersal of component species. Otherwise, rivers must be conceived as a landscape element with an intrinsic hierarchical nature and dispersal among its parts are constrained by this structure. Under this view, we also could expect that different basin or different “micro-basin” could present communities that are historically different in their general properties. Here, we aimed to describe odonate larval communities in the Pantanal Mortes-Araguaia river basin in Brazil comparing the composition, species richness and community structure between lakes and rivers, and also the possible differences among river basins. The field work was done in three rivers and three lakes chosen to conform to a paired experiment, each pair in a different river basin. An aggregated sampling unit was used based on Ekman dredge and D-nets replicated on each site. We sampled 936 individuals distributed in 30 genera and a total of 34 morphotypes. There was no difference in species richness among lakes and rivers, but a marked difference among basins. Samples from the same basin present a higher similarity of the species abundance relations than among river or lake samples. We also did not observed differences in composition and community structure between large rivers and lakes, in the same basin. The results supported the concept of structural similarity between large rivers and lakes and the differences observed among basins could indicate historical events in colonization that are shaping communities characteristics.
The aim of our study was to characterize Cerataphis brasiliensis Hempel, an aphid of native palm ... more The aim of our study was to characterize Cerataphis brasiliensis Hempel, an aphid of native palm tree of tropical savannas (cerrado), and to record intraspecific variation. We found two parthenogenetic forms of apterous viviparae females of C. brasiliensis. We differentiate the two forms through measurable and qualitative characters: (i) length of cephalic horns, (ii) number of antennal segments, (iii) presence or absence of wax glands, (iv) location of siphunculi.
Aquatic insects are widely distributed, and are especially diverse and abundant in tropical strea... more Aquatic insects are widely distributed, and are especially diverse and abundant in tropical streams, where they play an important role in the food chain due to their diversity of feeding strategies, and the potential for the transfer of energy between aquatic and terrestrial environments. The intimate relationship found between these insects and environmental variables means that they are often used as bioindicatorss in environmental studies. We tested the hypothesis that the loss of environmental integrity in tropical streams will lead to a loss of species and a decline in the abundance of mayflies (Leptophlebiidae), in addition to a change in species composition, and the dynamics of population. Collect immature leptophlebiids in 18 streams representing different DEGREES of conservation, in the Brazilian Cerrado. The environmental integrity of the sites was assessed using a Habitat Integrity Index (HII), which generates values of zero (degraded) to one (preserved), based on soil use, the extension and conservation of riparian forest, as well as morphological features of the stream. A total of 4945 immature leptophlebiids were collected and identified as belonging to 16 species or morphospecies. On an average, a reduction of 0.1 in the value of the HII led to the loss of five specimens and one species. The composition of the communities varied systematically along the environmental gradient, with more sensitive species being found only when the index was above a threshold of 0.6. The importance of the riparian vegetation for the aquatic biota, especially its role in the mitigation of impacts from the surrounding matrix, supports the universal conservation of this type of habitat.
Effects of riparian vegetation removal on body size and wing fluctuating asymmetry (FA) of Argia ... more Effects of riparian vegetation removal on body size and wing fluctuating asymmetry (FA) of Argia tinctipennis Selys (Odonata: Coenagrionidae) were studied in the River Suiá-Miçú basin, which is part of the Xingu basin in Brazilian Amazonia. A total of 70 specimens (n = 33 from preserved and n = 37 from degraded areas) was measured. Five wing measures of each wing (totalizing ten measured characters) were taken. Preserved and degraded points presented non-overlapped variations of a Habitat Integrity Index, supporting the environmental differentiation between these two categories. FA increases in degraded areas approximately four times for the width between the nodus and proximal portion of the pterostigma of forewings (FW), two times for the width of the wing in the region of nodus of FW, and approximately 1.7 times for the number of postnodal cells of FW. The increase is almost five times for the width between the nodus and the proximal portion of the pterostigma of hind wings (HW), three times for the number of postnodal cells of HW, and approximately 1.6 times the width between quadrangle and nodus of HW. Individuals of preserved sites were nearly 3.3% larger than for degraded sites, based on mean hind wing length. Our results supports that the development of A. tinctipennis in degraded areas is affected by riparian vegetation removal and may reflect in wing FA variations. Consequently, these FA measures may be a useful tool for bioassessment using Odonata insects as a model.
Effect of the abiotic factors on Brachymetra albinervis albinervis (Heteroptera: Gerridae). We an... more Effect of the abiotic factors on Brachymetra albinervis albinervis (Heteroptera: Gerridae). We analyzed the influence of abiotic factors, longitudinal and temporal distribution on the abundance of Brachymetra albinervis albinervis Amyot & Serville, 1843. Three sites of Cerrado stream were assessed: headwater, intermediary and river mouth, monthly for a year (June 2011 to May 2012). At each site, the following abiotic variables were monthly measured in a linear 100 meters transect: dissolved oxygen, water temperature, pH, electrical conductivity, width and depth of the stream. Were collected 111 specimens. The river mouth presented lower abundance when compared with others sites (F (2,9) = 13.721, p = 0.001). The periods of the year (rain, ebb, dry or early rains), there was no differences in the abundance. Thus, the abundance of B. a. albinervis analyzed for one year showed variation only in the streams longitudinal distribution, which was attributed to the effect of environmental changes in the river mouth, where presented lower abundance and less environmental integrity. These results contribute to the ecological knowledge of this species and discusses the change in the occurrence and abundance this species due to alteration in aquatic environments. RESUMO. Analisou-se a influência de fatores abióticos, distribuição longitudinal e temporal sobre a abundância de Brachymetra albinervis albinervis Amyot & Serville, 1843. Foram avaliados três sítios de um riacho de Cerrado: nascente, intermediário e foz, mensalmente durante um ano (junho de 2011 a maio de 2012). As variáveis abióticas aferidas foram: oxigênio dissolvido, temperatura da água, pH, condutividade elétrica, largura e profundidade do riacho. Em cada sítio, mensalmente coletou-se em transecção de 100 m lineares. Foram coletados 111 espécimes. A foz apresentou menor abundância quando comparada aos outros locais (F (2, 9) 13,721, p = 0,001). A abundância não variou entre os períodos do ano (chuva, vazante, seca ou início da chuva). Assim, a alteração na abundância de B. a. albinervis analisada ao longo de um ano foi influenciada pelos trechos do córrego, e essa variação foi atribuída a alterações ambientais no sítio foz que apresentou menor abundância e consequentemente é o que apresenta menor integridade ambiental. Esses resultados contribuem para o conhecimento ecológico dessa espécie e discute sobre a mudança da ocorrência da espécie em função da alteração dos ambientes aquáticos.
The ocurrence of males, gamic and ambiohasic females of the greenbug Schizaphis graminum (Rondani... more The ocurrence of males, gamic and ambiohasic females of the greenbug Schizaphis graminum (Rondani, 1852) among parthenogenetics reared on Sorghum bicolor (Linnaeus) Moench, in Ribeirão Preto (São Paulo, Brazil), from 1980 through 1983, follows an annual cycle. They appear from April through June, when the photoperiod has about 11 hours of daily photophase. Despite the low number these findings support the potential for holocycle, triggered by variable abiotic factors in this region with mild winters.
Structural properties of aquatic habitats are the basis of several theories produced to explain t... more Structural properties of aquatic habitats are the basis of several theories produced to explain the functioning of aquatic environments. We predicted a longitudinal change of ecosystem properties along the river, and also that potamal areas of the river are similar to lakes. In rivers with periodic floods we also expect a high degree of similarity due to increased environmental similarity and increase dispersal of component species. Otherwise, rivers must be conceived as a landscape element with an intrinsic hierarchical nature and dispersal among its parts are constrained by this structure. Under this view, we also could expect that different basin or different “micro-basin” could present communities that are historically different in their general properties. Here, we aimed to describe odonate larval communities in the Pantanal Mortes-Araguaia river basin in Brazil comparing the composition, species richness and community structure between lakes and rivers, and also the possible differences among river basins. The field work was done in three rivers and three lakes chosen to conform to a paired experiment, each pair in a different river basin. An aggregated sampling unit was used based on Ekman dredge and D-nets replicated on each site. We sampled 936 individuals distributed in 30 genera and a total of 34 morphotypes. There was no difference in species richness among lakes and rivers, but a marked difference among basins. Samples from the same basin present a higher similarity of the species abundance relations than among river or lake samples. We also did not observed differences in composition and community structure between large rivers and lakes, in the same basin. The results supported the concept of structural similarity between large rivers and lakes and the differences observed among basins could indicate historical events in colonization that are shaping communities characteristics.
The aim of our study was to characterize Cerataphis brasiliensis Hempel, an aphid of native palm ... more The aim of our study was to characterize Cerataphis brasiliensis Hempel, an aphid of native palm tree of tropical savannas (cerrado), and to record intraspecific variation. We found two parthenogenetic forms of apterous viviparae females of C. brasiliensis. We differentiate the two forms through measurable and qualitative characters: (i) length of cephalic horns, (ii) number of antennal segments, (iii) presence or absence of wax glands, (iv) location of siphunculi.
Aquatic insects are widely distributed, and are especially diverse and abundant in tropical strea... more Aquatic insects are widely distributed, and are especially diverse and abundant in tropical streams, where they play an important role in the food chain due to their diversity of feeding strategies, and the potential for the transfer of energy between aquatic and terrestrial environments. The intimate relationship found between these insects and environmental variables means that they are often used as bioindicatorss in environmental studies. We tested the hypothesis that the loss of environmental integrity in tropical streams will lead to a loss of species and a decline in the abundance of mayflies (Leptophlebiidae), in addition to a change in species composition, and the dynamics of population. Collect immature leptophlebiids in 18 streams representing different DEGREES of conservation, in the Brazilian Cerrado. The environmental integrity of the sites was assessed using a Habitat Integrity Index (HII), which generates values of zero (degraded) to one (preserved), based on soil use, the extension and conservation of riparian forest, as well as morphological features of the stream. A total of 4945 immature leptophlebiids were collected and identified as belonging to 16 species or morphospecies. On an average, a reduction of 0.1 in the value of the HII led to the loss of five specimens and one species. The composition of the communities varied systematically along the environmental gradient, with more sensitive species being found only when the index was above a threshold of 0.6. The importance of the riparian vegetation for the aquatic biota, especially its role in the mitigation of impacts from the surrounding matrix, supports the universal conservation of this type of habitat.
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