Rural depopulation on agricultural technological choice in China / Efeito do despovoamento rural na escolha tecnológica agrícola na China

Rural depopulation is an inevitable trend due to urbanization and industrial development, and it is a common phenomenon in industrialized countries. The classic theory of induced technological innovation proposed by HAYAMI & RUTTAN (1971) explains the change in agricultural technology during the process of rural depopulation. This paper tests the Hayami-Ruttan induced technological innovation theory from the perspective of agricultural technology choice in the process of rural depopulation. We sort out the influence mechanism of rural depopulation on the choice of agricultural technology from four aspects, namely, factor substitution effect, demand scale effect, conditional bottleneck effect, and agricultural comparative benefit. Using the difference between the rural registered population and the permanent population, we comprehensively compiled the data on the net outflow rate of the rural population from 2005 to 2018 in 313 prefecture-level cities, and reach conclusions through panel regression. The results showed that rural depopulation is not necessarily conducive to labor-saving technological choices, but is conducive to the land-saving technological choice. However, rural depopulation promotes labor-saving technological choices when the population reaches a certain level. The conclusion is not completely consistent with the theory of Hayami-Ruttan, it reflects an idiographic feature of the Chinese environment.

O despovoamento rural é uma tendência inevitável devido à urbanização e ao desenvolvimento industrial, e é um fenômeno comum em países industrializados. A teoria clássica da inovação tecnológica induzida proposta por Hayami & Ruttan (1971) explica a mudança na tecnologia agrícola durante o processo de despovoamento rural. Este artigo testa a teoria da inovação tecnológica induzida por Hayami-Ruttan sob a perspectiva da escolha da tecnologia agrícola no processo de despovoamento rural. Classificamos o mecanismo de influência do despovoamento rural na escolha da tecnologia agrícola a partir de quatro aspectos, a saber, efeito de substituição de fatores, efeito de escala de demanda, efeito de gargalo condicional e benefício comparativo agrícola. Usando a diferença entre a população rural registrada e a população permanente, compilamos de forma abrangente os dados sobre a taxa líquida de saída da população rural de 2005 a 2018 em 313 cidades em nível de prefeitura e chegamos a conclusões por meio de regressão em painel. Os resultados mostram que o despovoamento rural não é necessariamente propício para a escolha tecnológica de economia de mão de obra, mas é propício para a escolha tecnológica de economia de terra. No entanto, o despovoamento rural promove escolhas tecnológicas que economizam mão-de-obra quando a população atinge um certo nível. A conclusão não é totalmente consistente com a teoria de Hayami-Ruttan, ela reflete uma característica idiográfica do ambiente chinês.

Community-Based Approach for Agricultural Water Management of Summer Crops / Abordagem comunitária para gestão de águasvoltada para culturas agrícolas de verão

Globalization, population change, and rural-to-urban movement are the main causes of the enormous issues faced by rural communities. Every growing nation, including the Kurdistan Region of Iraq (KRI), has a sizable proportion of rural farmers among its populace. This study was done in the Sulaimani Governorate, which was divided into six main districts namely; Garmian, Penjwin, Halabja, Chamchamal, Sharazur, and Raniya, and aimed to compare the groundwater level with summer crop water demand. The weighted Sum Method (WSM) and a Normalized Difference Vegetation Index map (NDVI) were used to analyze and illustrate the current water demand status for summer crops. The study employed a participatory research design, utilizing a purposive sampling method to select 60representative farmers, 25key decision-makers, representatives from Non-Governmental Organizations (NGOs), and experts in the field of water management. Data was collected through the use of focus group discussions (FGDs) and Key Informant Interviews (KIIs) to gather information from the selected participants. This study is innovative in its attempt to establish a correlation between the yield of summer crops and the availability of groundwater. As a conclusion for this study, the results suggest that thelevel of groundwater playsa significant role in determining the production of summer crops. Additionally, the sustainable development of various regions within the Sulaimani Governorate is influenced by a complex interplay of environmental, economic, andsocial factors. Future work will be focus on doing a detail research regarding time series for ground water level (GWL) vs.crop production vs.NDVI.(AU)

A globalização, a transição demográfica e o êxodo rural são as principais problemas enfrentados pelas comunidades rurais. Cada nação em crescimento, incluindo a região do Curdistão do Sul no Iraque, ainda mantém uma proporção considerável de agricultores em propriedades rurais. Este estudo foi feito na província de Sulaimani, que foi dividida em seis distritos principais, a saber; Garmian, Penjwin, Halabja, Chamchamal, Sharazur e Raniya, e teve como objetivo comparar o nível das águas subterrâneas com a demanda de água das culturas de verão existentes. O Método da Soma Ponderada e o índice de vegetação de diferença normalizada (IVDN) foram usados para analisar e ilustrar o estado atual da demanda de água para as culturas de verão da região. Oestudo empregou um projetode pesquisa participativa, utilizando um método de amostragem intencional para selecionar 60 agricultores representativos, 25 tomadores de decisão, representantes de organizações não governamentais e especialistas na área de gestão de recursoshídricos. Os dados foram coletados por meio do uso de discussões de grupos focais e entrevistas com pessoas-chave para coletar informações dos participantes selecionados. Este estudo é inovador em sua tentativa de estabelecer uma correlação entre o rendimento das culturas de verão e a disponibilidade de água subterrânea. Como conclusão para este estudo, os resultados sugerem que o nível das águas subterrâneas desempenha um papel significativo na determinação da produção de culturas de verão. Além disso, odesenvolvimento sustentável de várias regiões da província de Sulaimani é influenciado por uma complexa interação de fatores ambientais, econômicos e sociais. O trabalho futuro será focado em fazer uma pesquisa detalhada sobre séries temporais para nível de água subterrânea vs. produção agrícola vs. IVDN.(AU)

Life history trait variations and population dynamics of Calophysus macropterus (Siluriformes: Pimelodidae) in two river systems of the Colombian and Peruvian Amazon

The catfish Calophysus macropterus is heavily exploited in the Amazon basin, yet its life history characteristics are poorly documented, hampering proper fisheries management. In order to fill this gap, monthly sampling in the upper Putumayo River and in the Amazonas, lower Marañón and Ucayali (AMU) rivers were carried out over several years (2013-2015 in the AMU, 2013-2017 in the Putumayo) to provide detailed information about its reproduction, growth and mortality patterns (using length frequency data). Reproduction, which occurs during the dry and early flooding season, was only observed in the upper Putumayo River and not in the sampled portion of the AMU system, suggesting that the species reproduces closer to the Andes than other pimelodid catfishes. Size at first sexual maturity did not differ significantly among sex or among river systems, ranging from 25-28 cm SL. In both river systems, females had a faster growth than males and both genders also tended to have a better growth in the AMU than in the upper Putumayo. Mortality and exploitation estimate all indicated overexploitation of the species in both river systems. The implications of these results for fisheries management and conservation are discussed.(AU)

El bagre Calophysus macropterus está fuertemente explotado en la cuenca Amazónica. Sin embargo, su ciclo de vida está poco documentado, lo que dificulta su gestión pesquera. Para llenar este vacío, se realizaron muestreos mensuales en el alto río Putumayo alrededor de Puerto Leguízamo y en el Amazonas y los ríos bajo Marañón y Ucayali (AMU) cerca de Iquitos durante varios años (2013-2015 en AMU, 2013-2017 en Putumayo) para generar información sobre su reproducción, crecimiento y mortalidad. La reproducción, que se produce durante la estación seca y el inicio de la inundación, sólo se observó en el curso superior del río Putumayo y no en la parte muestreada del sistema de la AMU, lo que sugiere que la especie se reproduce más cerca de los Andes que otros pimelodidos. El tamaño de primera madurez sexual no difirió entre sexos o entre sistemas fluviales, oscilando entre 25-28 cm. En ambos sistemas fluviales, las hembras tuvieron un crecimiento más rápido que los machos y ambos géneros también tendieron a tener un mejor crecimiento en el AMU que en el alto Putumayo. Estimaciones de mortalidad y explotación indicaron una sobreexplotación en ambos sistemas. Se discuten las implicaciones de estos resultados para la gestión y conservación de las pesquerías.(AU)

GPS, LiDAR and VNIR data to monitor the spatial behavior of grazing sheep

Traditional knowledge about the behavior of grazing livestock is about to disappear. Shepherds well know that sheep behavior follows non-random patterns. As a novel alternative to seeking behavioral patterns, this study quantified the grazing activities of two sheep flocks of Churra breed (both in the same area but separated by 10 years) based on Global Position System (GPS) monitoring and remote monitoring sensing techniques. In the first monitoring period (2009-10), geolocations were recorded every 5 min (4,240 records), while in the second one (2018-20), records were taken every 30 min (7,636 records). The data were clustered based on the day/night and the activity (resting, moving, or grazing). An airborne LiDAR dataset was used to study the slope, aspect, and vegetation height. Four visible-infrared orthophotographs were mosaicked and classified to obtain the land use/land cover (LU/LC) map. Then, GPS locations were overlain on the terrain features, and a Chi-square test evaluated the relationships between locations and terrain features. Three spatial statistics (directional distribution, Kernel density, and Hot Spot analysis) were also calculated. Results in both monitoring periods suggested that the spatial distribution of free-grazing ewes was non-random. The flocks showed strong preferences for grazing areas with gentle north-facing slopes, where the herbaceous layer formed by pasture predominates. The geostatistical analyses of the sheep locations corroborated those preferences. Geotechnologies have emerged as a potent tool to demonstrate the influence of environmental and terrain attributes on the non-random spatial behavior of grazing sheep.

Aspects of the population dynamics of Anomalocardia brasiliana: subsidies for sustainable fishing in the west coast of Ceará, Brazil / Aspectos da dinâmica populacional de Anomalocardia brasiliana: subsídios para a pesca sustentável no Litoral Oeste do Ceará, Brasil

Shellfish gathering is an artisanal activity and a means of family subsistence for several coastal communities along the Brazilian coast and Anomalocardia brasiliana is one of the main exploited mollusk species. This paper aimed to obtain information about the temporal distribution, growth, yield, and gonadosomatic index of the bivalve mollusk A. brasiliana in a natural stock to provide subsidies for the sustainable extraction of this resource. The study was carried out in an area of the Acaraú River estuary, on Volta do Rio Beach, municipality of Acaraú, Ceará, Brazil. Samples were collected monthly for one year at spring low tide, using the random squares method. Water and sediment temperature and salinity were measured in situ. Sediment samples were collected for granulometric analysis. The specimens were individually quantified, measured, and weighed. A total of 8,507 A. brasiliana specimens were sampled, and the highest density recorded was 2,534 individuals/m2, whose longest shell length reached between 21 and 25 mm, while the mean meat yield was 12.42%. The means of biometric variables of individuals showed significant differences during the sample period. Frequency histograms evidenced the presence of adult and juvenile individuals, showing a continuous reproductive cycle in the studied natural stock. These results can assist the sustainable shellfish gathering activity on Volta do Rio Beach. We recommend that A. brasiliana is above 20 mm in length to be captured and the reduction in the capture effort from April to September, when the highest density of juveniles was observed, to guarantee the sustainability of this stock.

A mariscagem é uma atividade artesanal e meio de subsistência familiar de diversas comunidades litorâneas ao longo da costa brasileira, sendo Anomalocardia brasiliana uma das principais espécies de molusco exploradas. Esse trabalho objetivou obter informações sobre a distribuição temporal, crescimento, rendimento e o índice gonadossomático do molusco bivalve A. brasiliana em um estoque natural a fim de fornecer subsídios para a extração sustentável deste recurso. O estudo foi realizado em uma área do estuário do rio Acaraú, na Praia Volta do Rio, município de Acaraú, Ceará, Brasil. As coletas foram realizadas mensalmente durante um ano na maré baixa de sizígia, utilizando o método dos quadrados aleatórios. A temperatura da água, do sedimento e a salinidade foram aferidas in situ. Foram coletadas amostras de sedimento para análise granulométrica. Os espécimes foram quantificados, mensurados e pesados individualmente. Foram amostrados um total de 8.507 exemplares de A. brasiliana, a maior densidade registrada teve 2.534 indivíduos/m2, aqueles com maior comprimento de concha tinham entre 21 e 25 mm, o rendimento da carne apresentou um valor médio de 12,42%. As médias das variáveis biométricas dos indivíduos apresentaram diferenças significativas durante o período amostral. Os histogramas de frequência evidenciaram a presença de indivíduos adultos e juvenis, indicando um ciclo reprodutivo contínuo no estoque natural estudado. Estes resultados auxiliarão no exercício da mariscagem sustentável na praia da Volta do Rio. Recomenda-se a captura de A. brasiliana com comprimento acima de 20 mm e a redução do esforço de captura nos meses de abril a setembro, período em que foi observada a maior densidade de juvenis, a fim de garantir a sustentabilidade desse estoque.

Population dynamics and seasonality of Euspilotus (Hesperosaprinus) azureus Sahlberg (Coleoptera: Histeridae: Saprininae) / Dinâmica populacional e sazonalidade de Euspilotus (Hesperosaprinus) azureus Sahlberg (Coleoptera: Histeridae: Saprininae)

The effect of climatic conditions on the structure of populations has been perceived for different orders of insects and families of beetles. Here we described the population dynamics of Euspilotus azureus (Sahlberg, 1823) and determined its relationship with climatic variables. The specimens were collected monthly for one year in an area of Seasonal Semideciduous Forest, in Viçosa, Brazil. The seasonality of the population and of sexes was estimated through the absolute frequency of occurrence (AF) and the percentage frequency of occurrence (FO%) of the population and each sex, which were determined monthly. To test whether the changes in monthly AF of the population and of each sex are correlated with climatic variables, Spearman correlation tests were performed. To identify whether there are temporal fluctuations in the sex ratio, considering months and seasons, and within each season, we performed Chi-square tests. A total of 3,126 individuals (1,009 females and 2,117 males) were collected. The population had the highest abundance in spring and summer, and the lowest in autumn and winter. The highest AF and FO were found in December and January, and the lowest in June and July. The sex ratio of the population did not differ in the months of the year, but in the spring there was a marked predominance of males. For E. azureus, the temporal fluctuation in abundance of the population and in the sex ratio is related to the climatic variables of maximum temperature, humidity, and precipitation. Climatic variables, especially the temperature, provided a greater abundance of the population in the hottest and rainiest periods of the year for inducing reproductive activity and altering the population's sex ratio.

O efeito das condições climáticas na estrutura das populações tem sido percebido para diferentes ordens de insetos e famílias de besouros. Nós descrevemos a dinâmica populacional temporal de Euspilotus azureus (Sahlberg, 1823) e determinamos sua relação com as variáveis climáticas. Os espécimes foram coletados durante um ano em uma área de Floresta Semidecidual Sazonal, em Viçosa, Brasil. A sazonalidade da população e dos sexos foi estimada através da frequência de ocorrência absoluta (FA) e da frequência de ocorrência percentual (FO%) da população, as quais foram determinadas mensalmente. Para testar se as mudanças mensais na FA da população e de cada sexo estão correlacionadas com as variáveis climáticas, testes de correlação de Spearman foram realizados. Para identificar se há oscilações temporais na razão sexual considerando meses e estações, e dentro de cada estação, foram realizados testes de Qui-quadrado. Um total de 3.126 indivíduos (1.009 fêmeas e 2.117 machos) foram coletados. A população teve maior abundância na primavera e verão, e menor no outono e inverno. As maiores FA e FO foram em dezembro e janeiro, e a menores em junho e julho. A razão sexual da população não diferiu nos meses do ano, mas na primavera houve uma predominância marcante de machos. Para E. azureus, a flutuação temporal na abundância da população e na razão sexual é explicada pelas variáveis climáticas de temperatura máxima, umidade e precipitação. As variáveis climáticas, especialmente a temperatura, propiciaram uma maior abundância da população nos períodos os mais quentes e chuvosos do ano por induzirem a atividade reprodutiva e a alterar da razão sexual da população.

Effect of cowpea (Vigna unguiculata L. Walp) sowing season on population dynamics of pest insects

Several factors limit cowpea quality and yield, such as the choice of a cultivar better adapted to the region, the ideal sowing season, as well as diseases and pests. Aimed to evaluate the effect of different sowing seasons on the population dynamics of pest insects of cowpea crops. The study was carried out during the dry season, the rainy season, and the season recommended for sowing by the Experimental Farm of the Federal University of Amazonas (FAEXP­UFAM), Brazil. A total of 33 weekly collections were carried out during the three sowing seasons, distributed in two ways according to the phenological stage of the crop: manual collection per linear meter of plantation and entomological scanning net. The faunistic analysis detected the pest insects Acromyrmex laticeps nigrosetosus, Cerotoma arcuata, Crinocerus sanctus, Euschistus heros, Horciasinus signoreti, Liriomyza sativae, and Nezara viridula. Of these species, H. signoreti stands out for being recorded for the first time as predominant in cowpea crops in the Brazilian state of Amazonas. Infections by hemipterans such as C. sanctus, E. heros, H. signoreti, and N. viridula were detected throughout the study, regardless of the sowing season, except for H. signoreti, which was dominant in all three seasons. The highest infestation of C. arcuata occurred during the recommended sowing season for cowpeas (June to August). According to the Jaccard index, plantation I e II share 86% of the species. This study provides important information to programs in insect control and management and to the agronomic decision-making process.

Stock assessment of the peacock bass Cichla temensis (Humboldt, 1821), an important fishing resource from the middle Negro river, Amazonas, Brazil / Avaliação de estoque do tucunaré Cichla temensis, um importante recurso pesqueiro do médio rio Negro, Amazonas, Brasil

Peacock bass Cichla temensis is an important species at the Amazon basin, since commercial, subsistence and recreational fisheries simultaneously exploit it. Cichla temensis is the preferred species by recreational fishers and it has been strongly exploited, mainly at the Negro river, the second largest tributary of the Amazon River. It was used data from experimental fisheries, collected at the middle stretch of Negro river, which were coupled with previously published data on its population dynamics, to run a yield per recruit model and build scenarios of sustainable fisheries. The results showed that the age of the first catch is a key variable to successful management of the peacock bass stocks at this region.(AU)

O tucunaré Cichla temensis é uma importante espécie de peixe da bacia Amazônica, uma vez que esta espécie é simultaneamente explotada pela pesca comercial e de subsistência. Além disso, é preferida pelos pescadores esportivos que atuam na região do rio Negro, o segundo maior afluente do rio Amazonas. Foram usados dados de pescarias experimentais, coletados no trecho médio do rio Negro. Estes dados foram vinculados a outros dados, previamente publicados, sobre sua dinâmica populacional, para executar um modelo de rendimento por recruta e, dessa forma, construir cenários para pesca sustentável dessa espécie. Os resultados mostraram que a idade da primeira captura é uma variável chave para gerenciar, com sucesso, os estoques de tucunarés nesta região.(AU)

First report of inventory and role of macroinvertebrates and fish in Cautín river (38° S, Araucania region Chile) / Primeiro relato do inventário e papel dos macroinvertebrados e peixes no rio Cautín (39° S, região de Araucania Chile)

The Cautin river is located in the 137 years old Araucania region, Chile (38°S), and is characterized by alterations through human interference due agriculture and towns in its surrounding basin, the presence of salmonids, and by its mixed regime, originated from snow melting in summer and rains in winter. The aim of the present study was to make a review of the inventory and ecological role of the benthic inland water macroinvertebrates of the River Cautin, in order to understand their importance in the ecosystem of the river. The fauna of this river includes a fauna composed of endemic and introduced fish, which has, however, been only poorly studied until now. The literature revealed the presence of abundant populations of Diptera, Trichoptera and Ephemeroptera larval stages, and few crustaceans specifically amphipods and freshwater crabs along the river's course. Many of these macroinvertebrates are prey for both introduced salmonids and native fishes. Similar results have been reported for other southern Argentinean and Chilean Patagonian rivers.(AU)

O rio Cautin está localizado na região de Araucania, no Chile (38°S), é caracterizado por alterações através da interferência humana devido à agricultura e as cidades da bacia circundante, a presença de salmonídeos e pelo seu regime misto, originado pela queda de neve verão e chuvas no inverno. O objetivo do presente estudo foi fazer uma revisão do papel ecológico dos macroinvertebrados bentônicos das águas interiores do rio Cautin, para entender sua importância no ecossistema do rio. A fauna deste rio inclui uma fauna composta de espécies de peixes endêmicos e introduzidos, que, no entanto, tem sido mal estudada até agora. A literatura revelou a presença de abundantes populações de estádios de larvas Diptera, Trichoptera e Ephemeroptera, e poucos crustáceos especificamente anfípodes e caranguejos de água doce ao longo do curso do rio. Muitos desses macroinvertebrados são presas tanto para salmonídeos introduzidos quanto para peixes nativos. Resultados semelhantes foram relatados para outros rios sul da Patagônia Chilena e Argentina.(AU)

Spatial-temporal evolution characteristics and influencing factors of county rural hollowing in Henan / Características de evolução espacial e fatores de influência do êxodo rural do condado de Henan

Taking Henan province as an example, the index system of rural hollowing was constructed from three aspects of economy, population and land. Using the entropy weight method, hollowing index method, spatial autocorrelation analysis and Geo detector, spatial-temporal evolution characteristics and influencing factors of county rural hollowing from 2000 to 2013 in Henan province were analyzed. Results showed that the gap of rural hollowing between counties in Henan province expanded first and then decrease, and the whole province was at the middle level of rural hollowing, so the development of rural hollowing in Henan province was stable and positive. Spatial variation characteristics of different degrees rural hollowing during 2000-2013 were obvious, and the overall spatial pattern was higher in the northwest-southeast direction and lower in the northeast-southwest direction. There was a strong spatial positive correlation in rural hollowing, and spatial agglomeration was slightly weakened; the number of counties in H-H and L-L agglomeration areas was large and its agglomeration characteristics were obvious; the H-L agglomeration areas started from zero with a small number and scattered distribution. Influence of different factors on rural hollowing was quite different, and the per capita homestead area, the proportion of secondary and tertiary industries, the investment in fixed assets and the per capita net income of farmers were the dominant factors.(AU)

Tomando a província de Henan como exemplo, o sistema de índices de evasão rural foi construído a partir de três aspectos da economia, população e terra. Utilizando o método de peso de entropia, método de índice de vazamento, análise de autocorrelação espacial e Geo detector para analisar características de evolução espaço-temporal e fatores de influência do esvaziamento rural do município de 2000 a 2013 na província de Henan. Os resultados mostraram que a lacuna de esvaziamento rural entre condados na província de Henan foi expandida inicialmente e em seguida diminuiu, e toda a província estava no nível médio de evasão rural, e, além disso, o desenvolvimento da evasão rural na província de Henan era estável. As características de variação espacial de diferentes graus de evasão rural durante 2000-2013 eram óbvias, e o padrão espacial geral era mais alto na direção noroeste-sudeste e mais baixo na direção nordeste-sudoeste. Houve forte correlação positiva espacial no êxodo rural, e a aglomeração espacial foi levemente enfraquecida; o número de municípios nas áreas de aglomeração H-H e L-L era grande e as características de aglomeração eram óbvias; as áreas de aglomeração de H-L eram do zero com um pequeno número e distribuição dispersa. A influência de diferentes fatores no esvaziamento rural foi diferente, e a área de propriedade per capita, a proporção de indústrias secundárias e terciárias, o investimento em ativos fixos e a renda líquida per capita dos agricultores foram os fatores dominantes.(AU)

Relative growth and population dynamics of Macrobrachium iheringi (Decapoda, Palaemonidae)

During the ontogenetic development of crustaceans, the relative growth of some structures may change, especially during the transition from juvenile to adult. This study describes the relative growth of body structures of Macrobrachium iheringi, and provides information on its population dynamics, such as structure, fecundity, and morphological sexual maturity. The sampling of M. iheringi was carried out in Ribeirão da Hortelã, in Botucatu (SP, Brazil). The length of the carapace (CL), abdomen (AL), and ischium (IL), merus (ML), carpus (CrL), propodus (PpL), and dactyl (DcL) of the second right pereopod were measured. In addition, the width of the second abdominal pleura (PW) and propodus height (PpH) were included in analyses. The relationships that best demonstrated the changes in the allometric coefficient were CL vs PpL in males and females. The CL, in which males and females reach morphological sexual maturity, was estimated as 13.3 mm and 11.1 mm, respectively. The sex-ratio differed from the expected 1:1 and was skewed towards females. Precipitation and temperature influenced the abundance of different demographic classes. Macrobrachium iheringi has few but large eggs, which is expected since this species has an abbreviated larval development. Based on these results, we conclude that the propodus are good indicators of the size at onset of morphological sexual maturity. In addition, important information was obtained on the biology of M. iheringi, including its life cycle pattern, reproduction and influence of abiotic factors.

Growth parameters of the invasive gastropod Melanoides tuberculata (Müller, 1774) (Gastropoda, Thiaridae) in a semiarid region, Northeastern Brazil

Melanoides tuberculata has invaded several aquatic ecosystems in the Neotropical region. This species shows high adaptive capacity and plasticity, establishing itself in several basins, promoting negative impacts on environments and native species. Here, we determine the growth parameters and the population structure of this species, in a semi-arid environment, in Northeast Brazil (Pernambuco state). Monthly captures were conducted at three types of substrate: site 1: soft bottom with macrophytes, site 2: soft bottom without macrophytes, and site 3: gravel and rocks. Shells were classified as occupied or empty, and their shell length (SL) and opening width (SW) were measured. The growth parameters of the von Bertalanffy’s model were estimated from the size-length frequency distribution using the ELEFAN I. Also, the maturity was verified, through the size at onset of maturity (SOM - 14.85 mm SL) proposed in the literature. A total of 1,013 individuals were collected, with shells varying from 7 to 39 mm SL and mean density of 84.42 (± 3.86) individuals m-2. The substrate with the largest number of mollusks was the site 1. Largest amount of empty shells was detected at site 3. Growth of M. tuberculata indicates rapid increment, with k = 0.56, L∞ = 42 mm and t0 = -0.26 years. The mean estimated age for the species was 0.95 years. According to the SOM, 86% of individuals sampled were considered mature.

Relative growth and population dynamics of Macrobrachium iheringi (Decapoda, Palaemonidae)

During the ontogenetic development of crustaceans, the relative growth of some structures may change, especially during the transition from juvenile to adult. This study describes the relative growth of body structures of Macrobrachium iheringi, and provides information on its population dynamics, such as structure, fecundity, and morphological sexual maturity. The sampling of M. iheringi was carried out in Ribeirão da Hortelã, in Botucatu (SP, Brazil). The length of the carapace (CL), abdomen (AL), and ischium (IL), merus (ML), carpus (CrL), propodus (PpL), and dactyl (DcL) of the second right pereopod were measured. In addition, the width of the second abdominal pleura (PW) and propodus height (PpH) were included in analyses. The relationships that best demonstrated the changes in the allometric coefficient were CL vs PpL in males and females. The CL, in which males and females reach morphological sexual maturity, was estimated as 13.3 mm and 11.1 mm, respectively. The sex-ratio differed from the expected 1:1 and was skewed towards females. Precipitation and temperature influenced the abundance of different demographic classes. Macrobrachium iheringi has few but large eggs, which is expected since this species has an abbreviated larval development. Based on these results, we conclude that the propodus are good indicators of the size at onset of morphological sexual maturity. In addition, important information was obtained on the biology of M. iheringi, including its life cycle pattern, reproduction and influence of abiotic factors.(AU)

Growth parameters of the invasive gastropod Melanoides tuberculata (Müller, 1774) (Gastropoda, Thiaridae) in a semiarid region, Northeastern Brazil

Melanoides tuberculata has invaded several aquatic ecosystems in the Neotropical region. This species shows high adaptive capacity and plasticity, establishing itself in several basins, promoting negative impacts on environments and native species. Here, we determine the growth parameters and the population structure of this species, in a semi-arid environment, in Northeast Brazil (Pernambuco state). Monthly captures were conducted at three types of substrate: site 1: soft bottom with macrophytes, site 2: soft bottom without macrophytes, and site 3: gravel and rocks. Shells were classified as occupied or empty, and their shell length (SL) and opening width (SW) were measured. The growth parameters of the von Bertalanffys model were estimated from the size-length frequency distribution using the ELEFAN I. Also, the maturity was verified, through the size at onset of maturity (SOM - 14.85 mm SL) proposed in the literature. A total of 1,013 individuals were collected, with shells varying from 7 to 39 mm SL and mean density of 84.42 (± 3.86) individuals m-2. The substrate with the largest number of mollusks was the site 1. Largest amount of empty shells was detected at site 3. Growth of M. tuberculata indicates rapid increment, with k = 0.56, L∞ = 42 mm and t0 = -0.26 years. The mean estimated age for the species was 0.95 years. According to the SOM, 86% of individuals sampled were considered mature.(AU)

Abundance and population structure of Plesionika narval (Fabricius, 1787) in the Northeastern Atlantic / Abundância e estrutura populacional de Plesionika narval (Fabricius, 1787) no Atlântico Nordeste

Analysis of abundance and population structure of Plesionika narval was performed on data concerning 5,255 specimens obtained from 62 fishing sets carried out off the Madeira archipelago (Northeastern Atlantic) between 2004 and 2008 in a depth range from 101 to 350 m. Abundance ranged from 0.01 to 19.74 specimens-per-trap and significant differences were found between seasons, probably as a result of an increment of population in the spring during the recruitment season. The analysis of size distribution revealed that the carapace length (CL) ranged from 2.45 to 28.61 mm and that mean female size consistently exceeded that of males. Differences in mean CL were statistically significant between depth strata and seasons. Of the specimens sampled, 57.00% were males, 41.88% females and 1.42% undetermined. Sex ratio also differed significantly between seasons according to depth strata, consolidating the hypothesis of the existence of seasonal migrations related with the reproductive cycle of this species. Ovigerous females showed larger sizes and occurred all year around and remain in shallow waters in winter, summer and autumn and move to deeper waters in spring. The highest frequency of ovigerous females was recorded in summer, between 151 and 200 m deep supporting the hypothesis that spawning of this species occurs in shallow waters, especially in late summer.(AU)

O estudo de abundância e dinâmica populacional de Plesionika narval foi efetuado com 5.255 espécimes provenientes de 62 lances de pesca realizados ao largo do arquipélago da Madeira (Atlântico Nordeste) de 2004 a 2008 entre 101 e 350 m de profundidade. A abundância oscilou entre 0,01 e 19,74 espécimes-por-armadilha com diferenças significativas entre estações provavelmente devido ao aumento da população na primavera durante o período de recrutamento. A análise da distribuição de tamanhos revelou que o comprimento da carapaça (CL) variou entre 2,45 e 28,61 mm e que o tamanho médio das fêmeas excedeu o dos machos. Verificaram-se diferenças significativas no CL médio entre estrato de profundidade e estação. Do total amostrado, 57,00% foram machos, 41,88% fêmeas e 1,42% indeterminados. A razão de sexos também diferiu significativamente entre estações de acordo com a profundidade, consolidando a hipótese da existência de migrações sazonais relacionadas com o ciclo reprodutivo desta espécie. As fêmeas ovadas apresentaram maiores tamanhos e ocorreram durante todo o ano permanecendo em águas pouco profundas no inverno, verão e outono e migrando para águas profundas na primavera. A maior frequência de fêmeas ovadas foi registada no verão, entre 151 e 200 m de profundidade reforçando a hipótese de que a desova desta espécie ocorre em águas menos profundas, especialmente no final do verão.(AU)

Factors affecting the exit from farming of young farmers in Turkey: the case of Nigde province / Fatores que afetam a saída de jovens agricultores de propriedades rurais na Turquia: o caso da província de Nigde

This study has focused on the factor affecting the exit from farming of young farmers, since it is an important issue in many provinces of Turkey. Data obtained through face-to-face interview method with 85 selected young farmers (aged 15-40 years) engaged in agricultural activity in the Nide province in 2017. Logistic regression model based upon the dependent variable decision to exit from farming was used to determine relevant factors. According to results, number of children, the presence of house in the city center and the monthly income level has effects to exit from farming. Young farmers have priorities to reach a better life conditions for their children such as better education and health care services. Rural investment support should be increased; entrepreneurship and innovation trainings should be expanded by encouraging training on agriculture. It would be beneficial to develop different applications such as distance learning modules and digital agriculture.(AU)

Este estudo centrou-se no fator que afeta a saída da agricultura de jovens agricultores, uma vez que é uma questão importante em muitas províncias da Turquia. Dados obtidos através do método de entrevista presencial com 85 jovens agricultores selecionados (com idade entre 15 e 40 anos) envolvidos na atividade agrícola na província de Nide em 2017. Modelo de regressão logística baseado na variável dependente decisão de sair da agricultura foi usado para determinar fatores relevantes. De acordo com os resultados, o número de crianças, a presença de casa no centro da cidade e o nível de renda mensal tem efeitos para sair da agricultura de jovens agricultores na província de Nide. Os jovens agricultores têm prioridades para alcançar melhores condições de vida para seus filhos, como melhor educação e serviços de saúde. O apoio ao investimento rural deve ser aumentado e os treinamentos de empreendedorismo e inovação devem ser expandidos, incentivando a capacitação em agricultura. Com isso, seria benéfico desenvolver diferentes aplicações, como módulos de ensino à distância e agricultura digital.(AU)

Community structure and population dynamics of small mammals in an urban-sylvatic interface area in Rio de Janeiro, Brazil

The Atlantic Forest is one of the most disturbed Brazilian biomes, with 183 out of 298 species of mammals occurring in the state of Rio de Janeiro. In this study, we aimed to characterize the diversity, community structure, and habitat use of small mammals in the FIOCRUZ Atlantic Forest Campus (CFMA), including areas of Pedra Branca State Park (PBSP, subunit Pau da Fome), state of Rio de Janeiro. We also compared species diversity and composition between two moments 15 years apart (2001 and 2012-2015) and analyzed the population dynamics of the marsupial Didelphis aurita (Wied-Neuwied, 1826). Small mammal captures were made in different habitats: sylvatic-urban interface areas near human dwellings, disturbed forest, and preserved forest areas. Five marsupial species and four rodent species were captured in both periods. There was a reduction in species richness and β diversity between the two periods, indicating that disturbances in the environment over the years may have affected the small mammal community structure. The most altered environment showed the greatest species richness and abundance, while the forest areas showed the smallest values, which may be explained by the loss of mammal species, mainly specialist species in forested areas. We identified three groups of species according to habitat preferences: one related to environments with a higher density of vegetation in upper strata - Marmosa paraguayana (Tate, 1931) and Monodelphis americana (Müller, 1776), another related to a higher density in lower forest strata - Akodon cursor (Winge, 1887), and another with no association with the investigated habitat variables - D. aurita and Oligoryzomys nigripes (Olfers, 1818). The small mammal community structure showed a low level of nestedness in both sampling periods.[...](AU)

Effects of habitat heterogeneity on epiedaphic Collembola (Arthropoda: Hexapoda) in a semiarid ecosystem in Northeast Brazil

The spatial distribution of abiotic resources and environmental conditions can vary at small scales within terrestrial ecosystems, influencing the composition of soil fauna. Epiedaphic springtails (Collembola) of a semiarid Caatinga ecosystem were studied to determine if factors related to vegetation structure, such as species richness, aerial biomass, litterfall, and soil characteristics (pH, granulometry and soil organic matter), influence species richness and abundance of this group. A total of 5,513 individuals were collected of 15 species distributed in 13 genera and 9 families. The most abundant species were Temeritas sp., with 2,086 (38% of the total abundance) individuals, and Neotropiella meridionalis (Arlé, 1939), with 1,911 (35% of the total abundance) individuals. None of the variables in the regression model were significantly related to Collembola species richness, but abundance was significantly related to plant species richness, aerial biomass and soil pH. Thus, even at a small spatial scale, habitat heterogeneity influences the epiedaphic Collembola in the Caatinga ecosystem, especially their abundance.(AU)

Effects of habitat heterogeneity on epiedaphic Collembola (Arthropoda: Hexapoda) in a semiarid ecosystem in Northeast Brazil

The spatial distribution of abiotic resources and environmental conditions can vary at small scales within terrestrial ecosystems, influencing the composition of soil fauna. Epiedaphic springtails (Collembola) of a semiarid Caatinga ecosystem were studied to determine if factors related to vegetation structure, such as species richness, aerial biomass, litterfall, and soil characteristics (pH, granulometry and soil organic matter), influence species richness and abundance of this group. A total of 5,513 individuals were collected of 15 species distributed in 13 genera and 9 families. The most abundant species were Temeritas sp., with 2,086 (38% of the total abundance) individuals, and Neotropiella meridionalis (Arlé, 1939), with 1,911 (35% of the total abundance) individuals. None of the variables in the regression model were significantly related to Collembola species richness, but abundance was significantly related to plant species richness, aerial biomass and soil pH. Thus, even at a small spatial scale, habitat heterogeneity influences the epiedaphic Collembola in the Caatinga ecosystem, especially their abundance.

Community structure and population dynamics of small mammals in an urban-sylvatic interface area in Rio de Janeiro, Brazil

The Atlantic Forest is one of the most disturbed Brazilian biomes, with 183 out of 298 species of mammals occurring in the state of Rio de Janeiro. In this study, we aimed to characterize the diversity, community structure, and habitat use of small mammals in the FIOCRUZ Atlantic Forest Campus (CFMA), including areas of Pedra Branca State Park (PBSP, subunit Pau da Fome), state of Rio de Janeiro. We also compared species diversity and composition between two moments 15 years apart (2001 and 2012-2015) and analyzed the population dynamics of the marsupial Didelphis aurita (Wied-Neuwied, 1826). Small mammal captures were made in different habitats: sylvatic-urban interface areas near human dwellings, disturbed forest, and preserved forest areas. Five marsupial species and four rodent species were captured in both periods. There was a reduction in species richness and β diversity between the two periods, indicating that disturbances in the environment over the years may have affected the small mammal community structure. The most altered environment showed the greatest species richness and abundance, while the forest areas showed the smallest values, which may be explained by the loss of mammal species, mainly specialist species in forested areas. We identified three groups of species according to habitat preferences: one related to environments with a higher density of vegetation in upper strata - Marmosa paraguayana (Tate, 1931) and Monodelphis americana (Müller, 1776), another related to a higher density in lower forest strata - Akodon cursor (Winge, 1887), and another with no association with the investigated habitat variables - D. aurita and Oligoryzomys nigripes (Olfers, 1818). The small mammal community structure showed a low level of nestedness in both sampling periods.[...]