Aphrophoridae dynamic and feeding preference for plants in natural ground cover in olive groves from Trás-os-Montes

Xylella fastidiosa was recently detected in several regions of Europe. This phytopathogenic bacterium infects multiple plants species, among them important crops such as the olive tree. Insects belonging to Aprophoridae are the main potential vectors of X. fastidiosa in Europe. These insects are in general highly polyphagous, however they may prefer different plant species or families of plants. Currently X. fastidiosa has not been detected in Portugal but constitutes a serious risk since has been recently found in several regions from the Iberian Peninsula. Particularly, the olive orchard suffers important damages in other regions from Europe and the knowledge about potential vectors dynamics and feeding preferences is crucial for establishing prevention and control strategies. In this context, the preference for plants in natural ground cover and the dynamic of Aphrophoridae nymphs in olive orchards from Portugal was studied. The work was accomplished during springs 2017 and 2018 in two olive orchards. One of them was partially burned in 2016 and presented natural ground cover vegetation abnormally vigorous and the other was under integrated production. The number of plants with foams, the number of foams per plant, its position in the plant and the number of nymphs per foam were recorded. More than 90 plant species belonging to around 18 plant families were identified. One year after the fire, in 2017, more than 85% of the foams were observed in the post-fire orchard, with more ground cover by Fabaceae and less by Poaceae than the integrated orchard. In 2018 the Aphrophoridae abundance dramatically decreased. Foams were found mainly in plants belonging to Asteraceae and Fabaceae. Several plant families never presented foams. The obtained results will allow design a more efficient management of the vegetation ground cover with the goal of decrease the risk of infection with X. fastidiosa in Portuguese olive orchards.info:eu-repo/semantics/publishedVersio

Potential natural biocontrol agents of Aphrophoridae eggs

Xylella fastidiosa is a phytopathogenic bacterium detected recently in Europe. It causes important economical losses in different crops, mainly in olive, almond and vineyard. Up to now the Aphrophoridae Philaenus spumarius L. (1758) is the main identified vector in Europe. The information about Aphrophoridae biology is insufficient and the knowledge about its natural enemies reduced. Nymphs excrete spumes remaining protected from natural enemies. Therefore, eggs are likely the most vulnerable stage to the natural enemies action. In this work, the potential action of parasitoids, predators and fungi against eggs of Aphrophoridae was studied. For that, at the end of the winter and before the egg hatching, rests of the remaining vegetation in the ground cover, mainly Poaceae, were collected. In the laboratory leaves, particularly the interior part of the blade which is a common oviposition location for spittlebugs, were observed under binocular stereoscope. Viable eggs were introduced in petri dishes until hatching. A total number of eggs of 3841 in 322 eggs laying and with a mean of 12 eggs per egg laying was recorded. From them, 603 eggs were intact and 3238 had sings of natural control agent action. A potential action of predators (in 183 eggs laying), parasitoid (in 198 eggs laying) and entomopathogenic fungi (in 48 eggs laying) was observed. Additionally, 321 parasitoids emerged from 43 of the eggs laying. These results indicate that the eggs mortality due to beneficial organisms, particularly parasitoids, may have a high importance for the control of X. fastidiosa vectorsinfo:eu-repo/semantics/publishedVersio

A mathematical analysis of the evolution of perturbations in a modified Chaplygin gas model

One approach in modern cosmology consists in supposing that dark matter and dark energy are different manifestations of a single `quartessential' fluid. Following such idea, this work presents a study of the evolution of perturbations of density in a flat cosmological model with a modified Chaplygin gas acting as a single component. Our goal is to obtain properties of the model which can be used to distinguish it from another cosmological models which have the same solutions for the general evolution of the scale factor of the universe, without the construction of the power spectrum. Our analytical results, which alone can be used to uniquely characterize the specific model studied in our work, show that the evolution of the density contrast can be seen, at least in one particular case, as composed by a spheroidal wave function. We also present a numerical analysis which clearly indicates as one interesting feature of the model the appearence of peaks in the evolution of the density constrast.Comment: 21 pages, accepted for publication in General Relativity and Gravitatio

Presence and distribution of the African citrus psyllid in São Tomé island

The African citrus psyllid, Trioza erytreae (Hemiptera: Triozidae), is a natural vector of Candidatus Liberibacter spp., the causal agents of the citrus greening disease or Huanglongbing (HLB). Despite the global losses of the Citrus industry due to HLB, the vector is rapidly spread to new areas threatening citrus crops and raising con-cern for stakeholders. Until now, there was a single old register of T. er y treae from the São Tomé island (Bulletin of the British Museum of Natural History, Entomology, 49, 1–102). In this work, we provide up-to-date occurrence data on the presence of T. er y treae throughout the isle of São Tomé. The identity of the captured adults was assessed and confirmed through molecular identification by sequencing a portion of the mitochondrial COI. The psyllid was found in lemon, orange and tangerine or-chards. Further monitoring is advisable to manage potential outbreaksFundação para a Ciência e a Tecnologia, Grant/Award Number: LA/P/0007/2020 and UIDB/00690/2020; H2020 Environment, Grant/Award Number: H2020- SFS- 2018- 2 Topic SFS- 05- 2018-2019-2020; Foundation for Science and Technologyinfo:eu-repo/semantics/publishedVersio

Abundância e diversidade de coleópteros em olivais transmontanos

Os coleópteros, desempenham um papel importante no funcionamento dos agroecossistemas, uma vez que participam em processos ecológicos importantes como por exemplo a decomposição de matéria orgânica e reciclagem de nutrientes, e a regulação das populações de plantas e animais, entre outros. Pelo que o conhecimento da diversidade deste grupo taxonómico é da maior importância numa perspetiva de produção integrada de culturas. No olival os coleópteros podem ocupar diferentes nichos ecológicos, sendo de destacar a ação predadora de algumas famílias como contra pragas importantes da cultura. Neste sentido, com o presente trabalho pretendeu-se avaliar a abundancia e diversidade das famílias de coleópteros do olival na região de Trás-os-Montes. Assim, ao longo de dois anos distintos, 2012 e 2013, recorrendo à técnica de pancadas, com periodicidade semanal, de fevereiro a dezembro, foram amostrados quatro olivais. No total foram identificadas 27 famílias de coleópteros, que apresentaram variações ao longo do ano e entre anos. Sendo as famílias Scraptidae e Phalacridae as mais abundantes ao longo dos dois anos de amostragem. Em 2012, a família Coccinelladae apresentou elevada abundancia, sendo que várias espécies desta família desempenham papel importante na limitação natural de pragas do olival. Outras famílias de coleópteros predadores com Carabidae, Stafilinidae foram também observadas, mas com baixa abundância. A análise do número total de exemplares mostrou uma elevada variação anual, sendo a sua abundância muito superior em 2012.info:eu-repo/semantics/publishedVersio

Monitorização das principais pragas da amendoeira em pomares da região de Trás-os-Montes

Em Portugal, a cultura da amendoeira tem ganhado expressão crescente quer pela reconversão de pomares antigos ou de novas plantações, em Trás-os-Montes quer através de novas plantações, no Alentejo em qualquer dos casos com material vegetal estrangeiro. Paralelamente tem-se assistido a uma intensificação cultural, com maiores cuidados ao nível das fertilizações, rega e da proteção da amendoeira contra pragas e doenças. O último aspeto é de particular importância, uma vez que as pragas podem a uma redução quantitativa e qualitativa da produção e causar significativos.Projeto BioPest: Estratégias Integradas de Luta Contra Pragas-chave em Espécies de Frutos Secos PDR2020-101-030960info:eu-repo/semantics/publishedVersio

Monitorização das principais pragas da amendoeira em pomares da região de Trás-os-Montes

Em Portugal, a cultura da amendoeira tem ganhado expressão crescente, quer pela reconversão de pomares antigos ou de novas plantações em Trás-os-Montes, quer através de novas plantações no Alentejo, em qualquer dos casos com material vegetal estrangeiro. Paralelamente, tem-se assistido a uma intensificação cultural, com maiores cuidados ao nível das fertilizações, rega e da proteção da amendoeira contra pragas e doenças. O último aspeto é de particular importância, uma vez que as pragas podem levar a uma redução quantitativa e qualitativa da produção e causar prejuízos significativos. Neste sentido, em dois amendoais da região de Trás-os-Montes, um localizado em Alfândega da Fé e outro em Mirandela, semanalmente de abril a setembro de 2018, procedeu-se ao acompanhamento das principais pragas do amendoal. Para o efeito usaram-se: armadilhas com feromona sexual, para a anársia, Anarsia lineatella Zeller, e grafolita, Grapholita molesta Busck, a técnica de pancadas, para a monosteira, Monosteira unicostata (Mulsant & Rey, 1852), e a observação visual de órgãos atacados, para os afídeos, Myzus persicae Sulz., Brachycaudus amygdalinus Smith. e Brachycaudus helichrysi Kalt. Sempre que se justificou, colheram-se amostras de órgãos da planta para observação complementar em laboratório, com a exceção da monosteira, relativamente à qual se procedeu, semanalmente, à recolha de 20 folhas em 20 árvores para observação de ovos, ninfas e adultos, bem como do número de folhas com estragos visíveis. Os resultados obtidos indicam que para ambos os lepidópteros, anársia e grafolita, os níveis populacionais registados foram sempre muito baixos, não se justificando qualquer intervenção fitossanitária contra estas pragas. De igual modo, as populações de afídeos mantiveramse sempre em níveis que não causaram preocupação. A praga que atingiu os níveis populacionais mais elevados foi a monosteira. Este inseto observou-se durante todo o período de amostragem, registando maior incidência com a aproximação do verão altura em que atingiu o máximo de ninfas e adultos na segunda quinzena de agosto. A percentagem de folhas com estragos visíveis excedeu 70%, o que é indicativo da importância desta praga nos pomares de amendoeira da região.Monitoring of the main pests in almond orchards of the Trás-os-Montes region In Portugal, the almond crop has gained increasing expression, either by the conversion of old orchards or new plantations, in Trás-os-Montes, or through new plantations in Alentejo region, both with foreign plant material. At the same time, there has been a crop intensification with greater care in terms of fertilization, irrigation and protection of the almond tree against pests and diseases. The latter aspect is of particular interest, since pests can lead to a quantitative and qualitative loss of production. In this content, weekly from April to September, the main almond pests were followed in two orchards from the region of Trás-os-Montes, one located in Alfândega da Fé and another in Mirandela. Different sampling techniques were used: traps with sexual pheromone, for peach twig borer, Anarsia lineatella Zeller, and for oriental fruit moth, Grapholita molesta Busck; the beating technique, for poplar lace bug, Monosteira unicostata (Mulsant & Rey, 1852), and the visual observation of different plant organs, for aphids, Myzus persicae Sulz., Brachycaudus amygdalinus Smith. and Brachycaudus helichrysi Kalt. Whenever warranted, samples of plant materials were collected for further observation in the laboratory, with the exception of the poplar lace bug, which were weekly collected 20 leaves in 20 trees for observation of eggs, nymphs and adults, as well as the number of leaves with visible damages. The results indicate that for both Lepidoptera, population levels were always very low, which did not justify any intervention against these pests. Similarly, populations of aphids have always remained at levels that did not cause concern. The pest that reached the highest population levels was the poplar lace bug. This insect was observed throughout the period of sampling, registering a higher incidence with the approach of the summer where it reached the maximum of nymphs and adults in the second half of August. The percentage of leaves with visible damage exceeded 70%, which is indicative of the importance of this pest in the almond orchards of the region.Ao projeto BioPest: Estratégias Integradas de Luta Contra Pragas-chave em Espécies de Frutos Secos PDR2020-101-030960info:eu-repo/semantics/publishedVersio

O2 mass transfer in an oscillatory flow reactor provided with smooth periodic constrictions : individual characterization of kL and a

In the present work the superficial gas velocities ( u G ) and the oscillatory conditions (frequency and amplitude) effects on the gas–liquid mass transfer process in a novel oscillatory flow reactor provided with smooth periodic constrictions (OFR-SPC) are experimentally evaluated. The liquid-side mass transfer coefficient, k L , and the specific interfacial area, a, are studied individually. The specific interfacial area is obtained using the new automatic image analysis technique developed by Ferreira et al. (2012). The experimental results of volumetric liquid side mass transfer coefficient ( k L a ), Sauter mean diameter ( d 32 ) and gas holdup ( ε G ), and the calculated values of a and k L , are correlated with the superficial gas velocity and the power density ( P / V ), in order to be used in scale-up processes and in comparisons with the literature. The results show that k L a increases with both superficial gas velocity and oscillatory conditions, the last ones having the highest impact on the mass transfer process. The increase in the oscillation motion (frequency and amplitude) results in bubble size reduction (from ∼7 mm, without oscillation, to ∼1 mm, with oscillation), in bubble average residence time increase and, consequently, in a increase. A k L increase with d 32 decrease is observed, showing the importance of hydrodynamic phenomena on k L , specially, when very low bubbles sizes are presented in oscillatory flow reactors.This work was supported by Fundacao para a Ciencia e Tecnologia under program contract number SFRH/BPD/45637/2008