52 research outputs found
Traveling wave solutions for a predator-prey system with Sigmoidal response function
We study the existence of traveling wave solutions for a diffusive
predator-prey system. The system considered in this paper is governed by a
Sigmoidal response function which is more general than those studied
previously. Our method is an improvement to the original method introduced in
the work of Dunbar \cite{Dunbar1,Dunbar2}. A bounded Wazewski set is used in
this work while unbounded Wazewski sets were used in \cite{Dunbar1,Dunbar2}.
The existence of traveling wave solutions connecting two equilibria is
established by using the original Wazewski's theorem which is much simpler than
the extended version in Dunbar's work
Global stability for a class of virus models with CTL immune response and antigenic variation
We study the global stability of a class of models for in-vivo virus
dynamics, that take into account the CTL immune response and display antigenic
variation. This class includes a number of models that have been extensively
used to model HIV dynamics. We show that models in this class are globally
asymptotically stable, under mild hypothesis, by using appropriate Lyapunov
functions. We also characterise the stable equilibrium points for the entire
biologically relevant parameter range. As a byproduct, we are able to determine
what is the diversity of the persistent strains.Comment: 15 page
Using Malaise traps to assess aculeate Hymenoptera associated with farmland linear habitats across a range of farming intensities
The intensification of farming practices, along with the loss and fragmentation of semi-natural habitats within agricultural areas, has contributed significantly to insect decline worldwide including flower-visiting aculeate Hymenoptera. In this study aculeate Hymenoptera were collected using bi-directional Malaise traps placed along farmland linear habitats across a range of farming intensities. The aim was to further our understanding of the value of farmland linear habitats to this insect group and in particular the Vespinae, an understudied subfamily. Overall, significantly greater aculeate Hymenoptera species richness was found on extensive than on intermediate and intensive farms. Significantly more species and specimens were collected on the side of the traps adjacent to the linear habitats compared to the side which opened onto the fields. Aculeate Hymenoptera species richness was also significantly greater in dense hedgerows than in open hedgerows. Furthermore, two out of six Vespinae species, Vespula rufa and Vespula vulgaris, had significantly more individuals on extensive than intensive farms. This study highlights that low-intensity farming practices and farmland linear habitats, especially dense hedgerows, may enhance aculeate Hymenoptera occurrence in agricultural areas. It also demonstrates that Malaise traps set up along linear habitats across a range of farming intensities can make a significant contribution to knowledge regarding the biodiversity value of such areas. Given that selected Vespinae species follow similar trends to aculeate Hymenoptera, the possibility of using them as simple biodiversity indicators is worthy of further exploration.© 2019 The Royal Entomological Societ
InfluĂȘncia de plantas invasoras na abundĂąncia de himenĂłpteros parasitoides (Insecta, Hymenoptera) coletados em cultura de coqueiro anĂŁo verde, em Linhares, ES, Brasil
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