Global ETD Search

1	The ecology and conservation of insectivorous bats in rural landscapes Lumsden, Linda F, mikewood@deakin.edu.au January 2004 (has links) Throughout the world, the increasing use of land for agriculture has been associated with extensive loss and fragmentation of natural habitats and, frequently, the degradation of remaining habitats. The effects of such habitat changes have been well studied for some faunal groups, but little is known of their consequences for bats. The aim of this study was to investigate the ecology and conservation of an assemblage of insectivorous bats in a rural landscape, with particular focus on their foraging and roosting requirements. This increased knowledge will, hopefully, assist the formulation of policy and management decisions to ensure the long-term survival of bats in these altered environments. The distribution and abundance of insectivorous bats in the Northern Plains of Victoria was investigated to determine the impacts of land-use change and to identify factors influencing the distribution of bats in rural landscapes. Thirteen species of insectivorous bats were recorded across the region by sampling at 184 sites. Two species were rare, but the remaining 11 species were widespread and occurred in all types of remnant wooded vegetation, ranging from large blocks (≥200 ha) to small isolated remnants (≤5 ha) and scattered trees in cleared farm paddocks. There was no significant difference between remnant types in the relative abundance of bat species, in species richness, or in the composition of bat assemblages at study sites. In a subsequent study, no difference in the activity levels of bats was found between remnants with different tree densities, ranging from densely-vegetated blocks to single paddock trees. However, sites in open paddocks devoid of trees differed significantly from all types of wooded remnants and had significantly lower levels of bat activity and a different species composition. In highly cleared and modified landscapes, all native vegetation has value to bats, even the smallest remnant, roadside and single paddock tree. Roost sites are a key habitat requirement for bats and may be a limiting resource in highly modified environments. Two species, the lesser long-eared bat Nyctophilus geoffroyi and Gould's wattled bat Chalinolobus gouldii, were investigated as a basis for understanding the capacity of bats to survive in agricultural landscapes. These species have different wing morphologies, which may be influential in how they use the landscape, and anecdotal evidence suggested differences in their roosting ecology. Roosting ecology was examined using radio-tracking to locate 376 roosts in two study areas with contrasting tree cover in northern Victoria. Both species were highly selective in the location of their roosts in the landscape, in roost-site selection and in roosting behaviour, and responded differently to differing levels of availability of roosts. The Barmah-Picola study area incorporated remnant vegetation in farmland and an adjacent extensive floodplain forest (Barmah forest). Male N. geojfroyi roosted predominantly within 3 km of their foraging areas in remnants in farmland. However, most female N. geoffroyi, and both sexes of C. gouldii, roosted in Barmah forest up to 12 km from their foraging areas in farmland remnants. These distances were greater than previously recorded for these species and further than predicted by wing morphology. In contrast, in the second study area (Naring) where only small remnants of wooded vegetation remain in farmland, individuals of both species moved significantly shorter distances between roost sites and foraging areas. There were marked inter- and intra-specific differences in the roosts selected. C. gouldii used similar types of roosts in both areas - predominantly dead spouts in large, live trees. N. geoffroyi used a broader range of roost types, especially in the farmland environment. Roosts were typically under bark and in fissures, with males in particular also using anthropogenic structures. A strong preference was shown by both sexes for roosts in dead trees, and entrance dimensions of roosts were consistently narrow (2.5 cm). In Barmah forest, maternity roosts used by N. geoffroyi were predominantly in narrow fissures in large-diameter, dead trees, while at Naring maternity roosts were also found under bark, in buildings, and in small-diameter, live and dead trees. The number of roost trees that are required for an individual or colony is influenced by the frequency with which bats move between roosts, the proportion of roosts that are re-used, the distance between consecutive roosts, and the size of roosting colonies. Both species roosted in small colonies and regularly shifted roost sites within a discrete roost area. These behavioural traits suggest that a high density of roost sites is required. There were marked differences in these aspects of behaviour between individuals roosting in Barmah forest and in the fragmented rural landscape. At Naring, N. geqffroyi remained in roosts for longer periods and moved greater distances between consecutive roosts than in Barmah forest. In contrast, C. gouldii used a smaller pool of roosts in the farmland environment by re-using roosts more frequently. Within Barmah forest, there is an extensive area of forest but the density of hollow-bearing trees is reduced due to timber harvesting and silvicultural practices. Individuals were selective in the location of their roosting areas, with both species selecting parts of the forest that contained higher densities of their preferred roost trees than was generally available in the forest. In contrast, in farmland at Naring, where there were small pockets of remnant vegetation with high densities of potential roost sites surrounded by cleared paddocks with few roosting opportunities, little selection was shown. This suggests that in Barmah forest the density of trees with potential roosts is lower than optimal, while in farmland roosting resources may be adequate in woodland remnants, but limiting at the landscape scale since more than 95% of the landscape now provides no roosting opportunities. Insectivorous bats appear to be less severely affected than some other faunal groups by habitat fragmentation and land-use change. A highly developed capacity for flight, the spatial scale at which they move and their ability to cross open areas means that they can regularly move among multiple landscape elements, rather than depend on single remnants for all their resources. In addition, bats forage and roost mainly at elevated levels in trees and so are less sensitive to degradation of wooded habitats at ground level. Although seemingly resilient to habitat fragmentation, insectivorous bats are fundamentally dependent on trees for roosting and foraging, and so are vulnerable to habitat loss and ongoing rural tree decline. Protection of the remaining large old trees and measures to ensure regeneration to provide ongoing replacement of hollow-bearing trees through time are critical to ensure the long-term conservation of bats in rural landscapes. insectivorous bats ecology Victoria conservation rural
2	The potential of using insectivorous bats (Microchiroptera) as a means of insect pest control in agricultural areas Marais, Werner Christiaan 03 June 2010 (has links) M.Sc. / Members of the Suborder Microchiroptera consume large numbers of insects. When large enough numbers of these bats are present in agricultural areas, the need for insecticides can be reduced significantly. The ZZ2 Tomato Farms in Mooketsi and the Secrabje Farm in Waterpoort, in the Limpopo Province were chosen as study sites. Although ZZ2 focuses on the production of tomatoes, both farms produce a variety of vegetables and fruit. These farms were chosen because the management of both have shown a commitment to conservation and attempt to minimise their impact on the environment. Bat species indigenous to the study areas were captured by means of mist nets for identification purposes. Basic morphological data of captured specimens were collected and recorded. Their roosting behaviour and preferences were studied by visiting diurnal roosts in the two study sites. Microclimatic measurements were taken in roosts occupied by Chaerephon pumilus, Mops condylurus and Taedarida aegyptiaca. Microclimatic measurements were also done in bat houses designed for the housing of bats in agricultural areas. Results suggest that other factors, additional to temperature and relative humidity, contribute to the success and probability of bat house occupancy by bats. Existing roosts in man-made structures such as roofs, can successfully be enhanced to stimulate increase in colony size. Bat activities were determined in agricultural areas and adjacent natural habitats by means of recordings of the echolocation calls of the different bat Families. These were compared to the occurrence of nocturnal flying insect orders that were captured in light traps at the same localities. Of the bat species studied, a positive correlation between increased bat activity and higher number of insects, including pest species, was found. It seems as if the Molossidae has the greatest potential to be utilised in the control of insect pests of agricultural areas in the Limpopo of the bat species studied. A holistic approach favouring insectivorous bats on farms is recommended. This can be done i.a. through the conservation of abundant areas of natural vegetation adjacent to the agricultural areas which would provide foraging for bats during winter, periods of drought or when the lands lie fallow. The excessive and injudicious use of insecticides, which has a negative effect on bats, counteracts the beneficial and cheap alternative of natural insect pest control provided by insectivorous bats. Bats Insect pests control Insectivorous bats Microchiroptera
3	Produção de anticorpos monoclonais para caracterização de variantes antigênicas brasileiras de vírus da raiva. / Production of monoclonal antibodies for characterization of brazilian antigenic variants of rabies virus. Chaves, Luciana Botelho 10 May 2010 (has links) Anticorpos monoclonais (AcMo) contra proteínas do vírus da raiva (RABV) foram produzidos para adequar a caracterização antigênica dos isolados no Brasil. Foram selecionados dois isolados de morcegos insetívoros, sendo um de Nyctinomops laticaudatus e outro de Eptesicus furinalis que apresentaram perfis não compatíveis (NC) com os pré-estabelecidos. As suspensões virais foram adaptadas para crescimento em cultura de células N2A. Para o preparo de AcMo foram utilizadas como antígeno as ribonucleoproteínas dos isolados selecionados. Foram obtidos dois AcMo, o 3A7 e o 4E10. Analisando 57 isolados de RABV com esses AcMo, o 3A7 reagiu com 21 (36,84%) e o 4E10 com 25 (43,85%). Dos 13 isolados caracterizados como variante antigênica 3 (Desmodus rotundus) o 3A7 reagiu com 8 (61,53%) e o 4E10 com 11 (84,61%). Dos 9 isolados com perfil NC em morcegos o 3A7 reagiu com 5 (55,55%) e o 4E10 com 4 (44,44%). Os anticorpos produzidos poderão auxiliar na complementação do painel existente de caracterização antigênica o que poderá aprimorar a vigilância epidemiológica da doença. / Monoclonal antibodies (MAb) against the rabies virus (RABV) proteins were produced to improve the antigenic characterization of the isolates in Brazil. Two isolates from insectivorous bats were selected; one was from the species Nyctinomops laticaudatus and the other from Eptesicus furinalis, which showed non-compatible (NC) profiles from pre-established ones. The viral suspensions were adapted for growth in N2A cells. Ribonucleoproteins from selected isolates were used as antigen for the preparation of Mab. We obtained two Mab, the 3A7 and the 4E10. Of the 57 RABV isolates analyzed with these MAb, the 3A7 reacted with 21 (36.84%) and 4E10 with 25 (43.85%). Of the 13 isolates characterized as antigenic variant 3 (Desmodus rotundus), the 3A7 MAb reacted with 8 (61.53%) and 4E10 with 11 (84.61%). Of the nine isolates with the profile NC of bats the 3A7 reacted with 5 (55.55%) and the 4E10 with 4 (44.44%). The antibodies produced may help to complement the existing panel to antigenic characterization which could improve the disease epidemiological surveillance. Anticorpos monoclonais Antigenic characterization Caracterização antigênica Insectivorous bats Monoclonal antibodies Morcegos insetívoros Rabies virus Vírus da raiva
4	Bats, insects and pecans: habitat use and ecosystem services of insectivorous bats in a pecan agroecosystem in central Texas Braun de Torrez, Elizabeth Claire 22 January 2016 (has links) Comprehensive wildlife conservation strategies must include consideration of the agricultural matrix and its integration into the greater landscape. Bats are postulated to provide critical pest suppression services, but the effects of agricultural intensification on insectivorous bats are not clear. Few studies have thoroughly investigated the ecosystem services provided by bats due, in part, to limited understanding of species-specific habitat use in agricultural landscapes, difficulties in prey identification, and the challenge of quantifying the impact of bats on pest populations and crops. My dissertation integrates these components to describe ecological relationships between the insects and bats associated with a pecan agroecosystem in central Texas. Specifically, I focus on the predator-prey relationship between bats and the pecan nut casebearer moth (PNC), a devastating pest of pecans. I begin with a literature review of the ecosystem services of insectivorous bats and the data necessary to thoroughly evaluate these services. I then assess the potential factors influencing species composition and spatio-temporal distributions of bats within the pecan agroecosystem. My results demonstrate higher activity and diversity of bats within the pecan agroecosystem than in the surrounding landscape likely due to roosting opportunities, but species-specific and seasonal differences exist in the effects of management intensity. Next, I investigate direct interactions between bats and PNC by measuring prey consumption patterns. I found that five species of bats prey upon PNC moths during all three critical population peaks prior to insecticide application, but there is variability in consumption among species. Finally, I assess indirect interactions between bats and pecans, by evaluating the effect of bat predation risk on pecan damage by PNC larvae. A negative relationship between foraging activity by bats and both PNC moths and PNC larval damage to pecans provides evidence that bat predation has quantitative downstream effects. My results highlight the conservation value of the agricultural matrix for bats and the complexities of accurately documenting ecosystem services provided by free-ranging mobile organisms. Ecology Dietary analysis Ecosystem services Insectivorous bats Pecan agroecosystem Pest suppression Predator-prey
5	Produção de anticorpos monoclonais para caracterização de variantes antigênicas brasileiras de vírus da raiva. / Production of monoclonal antibodies for characterization of brazilian antigenic variants of rabies virus. Luciana Botelho Chaves 10 May 2010 (has links) Anticorpos monoclonais (AcMo) contra proteínas do vírus da raiva (RABV) foram produzidos para adequar a caracterização antigênica dos isolados no Brasil. Foram selecionados dois isolados de morcegos insetívoros, sendo um de Nyctinomops laticaudatus e outro de Eptesicus furinalis que apresentaram perfis não compatíveis (NC) com os pré-estabelecidos. As suspensões virais foram adaptadas para crescimento em cultura de células N2A. Para o preparo de AcMo foram utilizadas como antígeno as ribonucleoproteínas dos isolados selecionados. Foram obtidos dois AcMo, o 3A7 e o 4E10. Analisando 57 isolados de RABV com esses AcMo, o 3A7 reagiu com 21 (36,84%) e o 4E10 com 25 (43,85%). Dos 13 isolados caracterizados como variante antigênica 3 (Desmodus rotundus) o 3A7 reagiu com 8 (61,53%) e o 4E10 com 11 (84,61%). Dos 9 isolados com perfil NC em morcegos o 3A7 reagiu com 5 (55,55%) e o 4E10 com 4 (44,44%). Os anticorpos produzidos poderão auxiliar na complementação do painel existente de caracterização antigênica o que poderá aprimorar a vigilância epidemiológica da doença. / Monoclonal antibodies (MAb) against the rabies virus (RABV) proteins were produced to improve the antigenic characterization of the isolates in Brazil. Two isolates from insectivorous bats were selected; one was from the species Nyctinomops laticaudatus and the other from Eptesicus furinalis, which showed non-compatible (NC) profiles from pre-established ones. The viral suspensions were adapted for growth in N2A cells. Ribonucleoproteins from selected isolates were used as antigen for the preparation of Mab. We obtained two Mab, the 3A7 and the 4E10. Of the 57 RABV isolates analyzed with these MAb, the 3A7 reacted with 21 (36.84%) and 4E10 with 25 (43.85%). Of the 13 isolates characterized as antigenic variant 3 (Desmodus rotundus), the 3A7 MAb reacted with 8 (61.53%) and 4E10 with 11 (84.61%). Of the nine isolates with the profile NC of bats the 3A7 reacted with 5 (55.55%) and the 4E10 with 4 (44.44%). The antibodies produced may help to complement the existing panel to antigenic characterization which could improve the disease epidemiological surveillance. Anticorpos monoclonais Caracterização antigênica Morcegos insetívoros Vírus da raiva Antigenic characterization Insectivorous bats Monoclonal antibodies Rabies virus
6	Bats in Urban Sweden : A multiple regression analysis of bats’ relationship to urbanization Andersson Skog, Nils January 2021 (has links) Human development continues to use up more physical space in the natural world, threatening the natural habitats of many organisms. To combat the loss of biodiversity science needs to explore what landscape features are important for different organisms so that we can incorporate these into the modern environment. As bats play an important role in many ecosystems and can reflect changes through trophic levels, analyzing their preferred habitats can help planners improve biological diversity of the urban habitat. Using acoustically identified bat sightings from Artportalen.se for the years 2017-2018, this paper studied the habitats of bats in Sweden. Through multiple regression analysis we examine the response in abundance and/or diversity of bats to physical and socio-cultural attributes of the urban habitat. We examined a total of 10160 bats from 18 species in 418 land cover locales and 306 demographical statistical areas with varying degrees of urbanization. Our results indicate that bat abundance and diversity decrease significantly with higher urbanization while deciduous forests are the most important land cover type for all bats. The results also indicate that wealthier areas have less abundance and diversity even when factoring in population density. Species specific analysis suggested that bat species who are better adapted at foraging in open vegetated landscapes and over water were less susceptible to the negative impacts of the urban habitat. We conclude that diverse habitats with a mixture of open vegetated areas, watercourses and broadleaf forests are the most important land features for a diverse bat fauna along with high connectivity via tree cover and linear landscape elements. If urban planning could incorporate these features into the urban habitat, some of the negative impacts of urbanization could be prevented. Urban ecology Insectivorous bats Chiroptera Species composition Bioindicator Sustainable development Ecology Ekologi
7	Du jeu des sélections chez une pyrale musicienne : étude de l'origine, de l'évolution et du maintien sélectif des comportements sexuels / On the selective interplays in an acoustic moth : a study of the origin, the evolution and the maintenance of sexual behaviours Alem, Sylvain 29 November 2012 (has links) Pour comprendre comment la sélection naturelle modèle les traits sexuels, l’emploi d’une approche intégrative des processus sélectifs en jeu semble aujourd’hui indispensable. Durant ma thèse je me suis ainsi intéressé aux influences simultanées des sélections de viabilité et sexuelle sur l’origine, l’évolution et le maintien des traits sexuels de la petite teigne de la ruche (Achroia grisella). Chez cette pyrale les mâles se regroupent en leks, produisent un chant d’appel ultrasonique intense et les femelles choisissent un partenaire sexuel en se basant sur des caractéristiques acoustiques spécifiques de ce chant. Cependant les signaux sexuels ultrasoniques des mâles peuvent également attirer des prédateurs : les chauves-souris insectivores. Ainsi, au sein des leks, les sélections sexuelle et de viabilité jouent et peuvent modeler (1) l’évolution du choix des femelles, (2) le maintien et l’évolution du lek, (3) l’origine de la communication acoustique sexuelle. Les travaux conduits durant cette thèse soulignent l’intérêt de l’étude du jeu des sélections sexuelle et de viabilité pour comprendre comment la sélection naturelle peut modeler l’origine, l’évolution et le maintien des traits sexuels. Les résultats indiquent en particulier le rôle crucial de la pression de prédation dans ces processus sélectifs. / In order to achieve a better understanding of how natural selection shapes sexual traits it is essential to consider the interplay of the various selective processes at work. For my thesis I investigated the simultaneous influences of viability and sexual selections on the origin, the evolution and the maintenance of sexual traits in the lesser waxmoth Achroia grisella. Females of this pyralid moth choose their mate based on acoustic characters of the ultrasonic calling song broadcasted by males while competing at lek. However male ultrasonic displays are very conspicuous and may attract specific predators: insectivorous bats. Therefore at leks sexual and viability selection pressures act simultaneously and can shape (1) the evolution of female mate choice, (2) the maintenance and evolution of lekking, (3) the origin of sexual acoustic communication. Taken as a whole this work emphasises the relevance of the study of selective interplays between viability and sexual selections in order to improve our understanding of how natural selection may shape the origin, evolution and maintenance of sexual traits. In particular results indicate the crucial role played by predation pressure within these evolutionary processes. Sélection sexuelle Sélection de viabilité Communication acoustique Risque de prédation Choix de partenaire Évolution du lek Exploitation sensorielle Signaux ultrasoniques Chauves-souris insectivores Achroia grisella Sexual selection Viability selection Acoustic communication Predation risk Mate choice Evolution of leks Sensory exploitation Ultrasonic signals Insectivorous bats Achroia grisella
8	Birds, bats and arthropods in tropical agroforestry landscapes: Functional diversity, multitrophic interactions and crop yield Maas, Bea 20 November 2013 (has links) No description available. 630 birds bats arthropods multitrophic interactions agroforestry tropical landscape forest margin landscape functional diversity crop yield exclosure experiments experimental exclusion arthropod suppression avian predation ecosystem services mist netting point counts artificial plasticine caterpillar dummy experiment biological control monitoring mapping Lemon-bellied White-eye Grosbeak Starling Zosterops chloris Scissiostrum dubium Theobroma cacao cacao agroforestry cacao diseases cacao harvest cacao pests flying vertebrates aerial insectivores volant vertebrates logging breeding colony flower herbivory mesopredator release predatory insects ants spiders aphids Lepidoptera Coleoptera Lepidopteran larvae sustainable agriculture sustainable agroforestry management implications management recommendations applied managament extensive land use management landscape management conservation biodiversity-friendly dbh distance to forest forest proximity habitat conversion herbivory Indonesia insectivorous bats insectivorous birds invertebrates Central Sulawesi Napu valley leaf gleaning leaf herbivory pests insects phytophagous insects plant productivity remnant forest trees shade tree managament South-east Asia Paleotropics tropical landscape tree height landscape gradient local shade management Cacao Pod Borer Cherelle Wilt fruit abortion Helopeltis sulawesi deforestation habitat fragmentation land use intensification forest margin species critical decline predation experiment species-specific functions Southeast Asia biodiversity conservation mesopredators food security human welfare human well-being poverty alleviation poverty reduction smallholder cacao smallholder plantation cacao farmers sustainable cacao management landscape perspective landscape scale large scale field experiment long term field experiment human wellbeing economic importance economic value valuation ecosystem services landscape matrix yield quality yield quantity fruit productivity species identity species diversity species richness ecosystem functioning pesticide use chemical compounds complex food web tritrophic interactions wildlife-friendly rural livelihoods endangered bird species endangered bat species endemic endemic birds endemic bats beneficial impact IUCN Lore Lindu National Park bioindicator indicator species forest margin agricultural habitat agroforestry systems population density predation activity species activity cacao flower cacao pod Orthoptera linear mixed effect models Tukey Post Hoc Test AICc model selection generalized least squares restricted maximum likelihood model simplification species richness estimator species accumulation linear mixed-effects models Likelihood Ratio Test Maximum Likelihood nocturnal insects diurnal arthropods nocturnal arthropods diurnal insects landscape context Land- und Forstwirtschaft (PPN621302791)

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