A hierarchical topic modelling approach for tweet clustering

While social media platforms such as Twitter can provide rich and up-to-date information for a wide range of applications, manually digesting such large volumes of data is difficult and costly. Therefore it is important to automatically infer coherent and discriminative topics from tweets. Conventional topic models and document clustering approaches fail to achieve good results due to the noisy and sparse nature of tweets. In this paper, we explore various ways of tackling this challenge and finally propose a two-stage hierarchical topic modelling system that is efficient and effective in alleviating the data sparsity problem. We present an extensive evaluation on two datasets, and report our proposed system achieving the best performance in both document clustering performance and topic coherence

Record of Parasitoids in nests of social wasps (Hymenoptera: Vespidae: Polistinae)

The aim of this study was to record the parasitoid species found in social wasps nests sampled in different localities in Brazil and investigate the existence of preferential host-parasite associations in different tribes of Neotropical paper wasps. We sampled nests of Mischocyttarus cassununga, Mischocyttarus consimilis, Mischocyttarus imitator, Polistes canadensis, Polistes cinerascens, Polistes versicolor, Angiopolybia pallens, Leipomeles spilogastra, Polybia jurinei and two indeterminate species of Mischocyttarus. M. cassununga, M. imitator and Mischocyttarus (Phi) sp.1 were parasitized by Toechorychus guarapuavus (Ichneumonidae) and M. consimilis, M. imitator and Mischocyttarus sp. 2 was parasitized by Toechorychus fluminensis (Ichneumonidae). P. versicolor and P. cinerascens were parasitized by Elasmus polistes (Eulophidae) and P. canadensis by Simenota depressa (Trigonalidae); A. pallens and L. spilogastra, were infested by Brachymeria sp.1 and Brachymeria sp.2 (Chalcididae), respectively. M. cassununga and Polybia jurinei were parasitized by Megaselia scalaris (Phoridae). We suggested that there may be specific and preferential association between parasitoids and social paper wasps

Record of Parasitoids in nests of social wasps (Hymenoptera: Vespidae: Polistinae)

The aim of this study was to record the parasitoid species found in social wasps nests sampled in different localities in Brazil and investigate the existence of preferential host-parasite associations in different tribes of Neotropical paper wasps. We sampled nests of Mischocyttarus cassununga, Mischocyttarus consimilis, Mischocyttarus imitator, Polistes canadensis, Polistes cinerascens, Polistes versicolor, Angiopolybia pallens, Leipomeles spilogastra, Polybia jurinei and two indeterminate species of Mischocyttarus. M. cassununga, M. imitator and Mischocyttarus (Phi) sp.1 were parasitized by Toechorychus guarapuavus (Ichneumonidae) and M. consimilis, M. imitator and Mischocyttarus sp. 2 was parasitized by Toechorychus fluminensis (Ichneumonidae). P. versicolor and P. cinerascens were parasitized by Elasmus polistes (Eulophidae) and P. canadensis by Simenota depressa (Trigonalidae); A. pallens and L. spilogastra, were infested by Brachymeria sp.1 and Brachymeria sp.2 (Chalcididae), respectively. M. cassununga and Polybia jurinei were parasitized by Megaselia scalaris (Phoridae). We suggested that there may be specific and preferential association between parasitoids and social paper wasps

Genetic structure of drone congregation areas of Africanized honeybees in southern Brazil

As yet, certain aspects of the Africanization process are not well understood, for example, the reproductive behavior of African and European honeybees and how the first Africanized swarms were formed and spread. Drone congregation areas (DCAs) are the ideal place to study honeybee reproduction under natural conditions since hundreds of drones from various colonies gather together in the same geographical area for mating. In the present study, we assessed the genetic structure of seven drone congregations and four commercial European-derived and Africanized apiaries in southern Brazil, employing seven microsatellite loci for this purpose. We also estimated the number of mother-colonies that drones of a specific DCA originated from. Pairwise comparison failed to reveal any population sub-structuring among the DCAs, thus indicating low mutual genetic differentiation. We also observed high genetic similarity between colonies of commercial apiaries and DCAs, besides a slight contribution from a European-derived apiary to a DCA formed nearby. Africanized DCAs seem to have a somewhat different genetic structure when compared to the European

Notas sobre a socialidade e a biologia de nidificação de Trypoxylon (Trypoxylon) asuncicola Strand, 1910 (Hymenoptera, Sphecidae)

Notes on the sociality and nesting biology of Trypoxylon (Trypoxylon) asuncicola Strand, 1910 (Hymenoptera, Sphecidae). Twenty-two nests of Trypoxylon asuncicola were sampled in Viçosa, State of Minas Gerais, Brazil, in January 2000 and the occupants' behavior of three nests was registered in 2h of direct observation. 528 brood cells were excavated (24±13.84 SD cells per nest), 129 were reused cells, some of them for seven times (meconium deposit count). The mean number of total cells, mean number of open and closed cells, parasitism rate and mean number of reused cells per nest were similar between old and new nests. Parasitism rate and cell reuse were associated with the number of building cells in the nest, but nest aggregate in the sampled area may play some role in the parasitism rate. Brachymeria sp. (Chalcididae) was the most important agent of brood mortality (80%). Other parasites were Melittobia sp. (Eulophidae) (17%) and a species of Icheumonidae (3%). The number of closed cells with immature individuals per nest was 4±4.2SD (N=17) and the mean reproductivity per female was 3±2.4SD (N=5). New nests produced more offspring (0 a 35%) than old nests (0 to 11%). Females and males can be found resting in the nest but copula or guarding behavior by the male was not observed. There is some evidence that in the sampled area the switch of nests by females is great and agonistic behavior between a nest owner and a visitor was not evident. Females were larger (3.9±0.4SD mm) than males (3.1±0.3SD mm) (measured as forewing length). The secondary sex ratio was 1.26 (±0.07 SE) in favor of females, which was not different from 1:1 ratio. The majority (97%) of the sampled larvae of T. asuncicola showed diapause. Some (5.1%) 'anomalous cells' were found

Sex allocation and sex-dependent selection for body size in Trypoxylon rogenhoferi Kohl (Hymenoptera, Sphecidae) Alocação sexual e seleção sexo-dependente para tamanho de corpo em Trypoxylon rogenhoferi Kohl (Hymenoptera, Sphecidae)

Two populations of the wasp Trypoxylon rogenhoferi Kohl, 1884 from São Carlos and Luís Antônio, State of São Paulo, Brazil, were observed and sampled from May 1999 to February 2001 using trap-nests. This mass-provisioning wasp was used to test some aspects of optimal sex allocation theory. Both populations fit all the predictions of the models of Green and Brockmann and Grafen. Maternal provisions determined the size of each offspring, and females allocated well-stocked brood cells to daughters, the sex that benefits most being large. This strategy resulted in a difference in size between the sexes. In São Carlos, female weight at emergence was 1.18 times that of males, in Luís Antônio this value was 1.13. The brood cell volume was correlated with both wing length and weight at emergence in both sexes, and the chance that a given brood cell contained a male offspring decreased with increased brood cell volume. In T. rogenhoferi female body size was related to fitness. Larger females were able to collect more mass of spiders per day, the spiders they captured were heavier, and they provisioned more brood cells per day. They also produced larger daughters. For males, no relationship between body size and fitness was found, but the data were scarce. Since the patterns of provisioning were variable among different females in both study sites, it is possible that the females not follow a unique strategy for sex allocation. The sex ratio and/or investment ratio in the São Carlos population was female-biased and in Luís Antônio, male-biased. In spite of the influence of trap-nests diameters on male production in Luís Antônio, there is some evidence that in São Carlos population the local availability of prey and/or lower rate of parasitism may be major forces in determining the observed sex ratio, but further studies are necessary to verify such hypothesis

Biologia, comportamento social e alocação sexual de Digelasinus diversipes (Kirby, 1882) (Hymenoptera, Argidae)

São apresentados os resultados de um estudo de dois anos sobre o Symphyta neotropical Digelasinus diversipes. Esta espécie é univoltina e comum na Estação Ecológica Jataí, uma reserva de Cerrado no Estado de São Paulo. As larvas alimentam-se gregariamente em Eugenia glazioviana (Myrtaceae) de novembro a abril. Associações entre grupos de alimentação foram freqüentes. Após o período de alimentação, as larvas congregam-se e comunalmente constróem uma massa de casulos (105 casulos ± 60DP; n = 25) aderida ao tronco da planta hospedeira, permanecendo em diapausa como prepupas até o início da estação chuvosa, em outubro. O pico populacional foi observado em dezembro, quando 62% (n = 2.967) dos adultos emergiram. Em condições experimentais, foram observadas emergências das 6:30 às 15:00 h, mas 73,5% (n = 223) dos adultos emergiram entre 9:00 e 12:00 h. Não foi observado, durante a emergência, sequenciamento sexual, mas em um agregado de casulos os machos podem emergir de 20 a 40 dias antes das fêmeas. Após a emergência os machos podem (1) dispersar-se (no início e final do período de emergência; outubro e novembro, janeiro e fevereiro, respectivamente) ou (2) permanecer sobre ou próximo ao agregado de casulos e copular com as fêmeas recém-emergidas (durante o pico de emergência, em dezembro). As cópulas duraram 4,28 minutos (± 3,4DP; n = 28). Ao longo do dia, os machos podem copular com diferentes fêmeas (1-8; n = 5); contudo, as fêmeas copularam apenas uma vez. Em média, as fêmeas emergem com 76 (± 21DP; n = 19) ovos maduros e todos eles são ovipositados de uma só vez sob uma única folha da planta hospedeira. A guarda dos ovos pelas fêmeas durou apenas 2 dias (n = 12) dos 30 necessários para sua incubação. O repertório de comportamentos da fêmea contra potenciais inimigos foi menor do que o observado em outras espécies de Symphyta. Aparentemente, a fêmea induz um necrosamento do tecido foliar que cobre os ovos. Isto formaria uma proteção rígida para os ovos durante sua incubação. Em D. diversipes, adultos de ambos os sexos não se alimentaram (condição controlada) e tiveram vida curta (5,2 dias ± 1,7DP; mínimo 1, máximo 11; n = 179). A razão sexual média foi 2,83 (± 0,014EP) em favor de fêmeas. Os principais fatores de mortalidade foram falhas no desenvolvimento, falta de alimento devido à intensa herbivoria e ataque de parasitóides. Parasitóides criados, Lymeon dieloceri (Costa Lima, 1937) (Ichneumonidae), Conura (Spilochalcis) sp. (Chalcididae) e Perilampus sp. (Perilampidae)

Neotropical Polistinae (Vespidae) and the Progression Rule Principle: the Round-Trip Hypothesis

The progression rule principle is based on the relation between centers of origin and basal forms, and the prediction that recently colonized areas are where novelties commonly occur. Using this concept as the null hypothesis, the aim of the present study was to test whether intuitive predictions of this model are confirmed in the Neotropical paper wasps, a group fairly studied through phylogenetic frameworks. The analyses consisted of a careful review of the distribution of different wasps of the subfamily Polistinae with available phylogenies and the association of this information with colonization routes. This procedure allowed the determination of a two-step colonization process in the Neotropical region based on the progression rule principle, for which the round-trip hypothesis is proposed. The first route (east to west) is seen in a small group of Polistes. This route is rare but strengthens the arising of paper wasps in the Americas in a Gondwanan scenario. The second route (west to east) is remarkably repeated in several other lineages. Thus, the northwestern Neotropics, mainly Amazon Forest, is proposed as the major center of origins for living Neotropical Polistinae and the round-trip hypothesis may explain both earlier and later colonization routes of the paper wasps analyzed. © 2015, Sociedade Entomológica do Brasil

External morphological structures observed.

<p>View frontal of head, (a) <i>S</i>. <i>surinama</i> and (b) <i>S</i>. <i>septentrionalis</i>. View frontal of scape, (c) <i>S</i>. <i>cyanea</i> and (d) <i>S</i>. <i>septentrionalis</i>. Scutum in lateral view, (e) <i>S</i>. <i>surinama</i> and (f) <i>S</i>. <i>septentrionalis</i>.</p