Insects of the family Cercopidae are easily identified by the spit-like foam that they produce to surround themselves during the nymphal stage. Known as spittlebugs, these insects can be observed developing in a wide range of host plants. Among the functions attributed to the foam, there are the protection of nymphs against high temperatures, desiccation and natural enemies. However, experimental evidence to confirm these hypotheses are sparse. Mahanarva fimbriolata is an economically important spittlebug in Brazilian sugarcane crops, especially after the harvest with burning had been prohibited. The nymphs of M. fimbriolata develop on the soil surface or below ground where they suck the xylem content of exposed sugarcane roots, blocking the water and nutrients transport, eventually causing physiological disorder. In this thesis, it was evaluated the importance of foam for the thermoregulation of M. fimbriolata nymphs, its bacterial microbiome and the protective action against predators. The thesis was divided into four chapters. The Chapter 1 presented an introduction to the bioecological aspects of M. fimbriolata and the possible role of foam produced by the nymphs, which was explored in details along the other chapters. The Chapter 2 examined the importance of foam and its chemical compounds in the thermoregulation of nymphs. The Chapter 3 explored the diversity and composition of bacterial community present in the foam, in the gut of nymphs, and in the soil close to the foam. The Chapter 4 investigated whether the foam acts in protecting the nymphs against the predatory ants Solenopsis invicta, and its topical irritancy to the cockroaches Periplaneta americana. It was demonstrated that the foam produced by M. fimbriolata: (i) serves as an important thermal microhabitat, maintaining the temperature close to the ideal for the nymphs development; (ii) harbor a diversity of bacteria previously reported as protective symbionts of insects, which are probably originated from the nymphs\'s gut; and (iii) is a repellent to predators and topical irritant to another arthropod (roaches). Taken together, the foam produced by M. fimbriolata is a thermoregulatory and defensive strategy to the nymphs. In addition, this thesis serves as a background for future research that aims to investigate the importance of foam for the growth and development of spittlebugs. / Os insetos da família Cercopidae são facilmente reconhecidos pela espuma que produzem durante o desenvolvimento ninfal para recobrir o próprio corpo. Essas ninfas, conhecidas como cigarrinhas, podem ser observadas em uma ampla gama de plantas hospedeiras. Dentre as funções atribuídas à espuma estão a proteção contra elevadas temperaturas, dessecação e inimigos naturais. Contudo, evidências experimentais para confirmar estas hipóteses são escassas. Mahanarva fimbriolata é uma cigarrinha de importância econômica em áreas de produção de cana-de-açúcar no Brasil, especialmente após a proibição da colheita da cana com queima prévia. As ninfas de M. fimbriolata se desenvolvem nas raízes de cana-de-açúcar expostas na superfície ou abaixo do solo, onde sugam a seiva do xilema, bloqueando o transporte de água e nutrientes e causando desordens fisiológicas. Nesta tese foi avaliada a importância da espuma para a termorregulação de ninfas de M. fimbriolata, seu microbioma bacteriano e sua ação protetora contra predadores. A tese foi dividida em quatro capítulos. O Capítulo 1 apresenta uma introdução sobre os aspectos bioecológicos de M. fimbriolata e o possível papel da espuma produzida pelas ninfas, o qual foi explorado em detalhes ao longo dos demais capítulos. O Capítulo 2 examinou a importância da espuma e de seus compostos químicos na termorregulação das ninfas. O Capítulo 3 explorou a diversidade e composição da comunidade bacteriana presente na espuma, no intestino das ninfas, e no solo próximo à espuma. O Capítulo 4 investigou se a espuma atua na sua proteção das ninfas contra formigas predadoras Solenopsis invicta, e sua irritação tópica a baratas Periplaneta americana. A espuma produzida por M. fimbriolata demonstrou: (i) servir como um importante microhabit térmico, mantendo a temperatura próxima da ideal para o desenvolvimento das ninfas; (ii) abrigar uma diversidade de bactérias previamente reportadas como simbiontes protetivos de insetos e que, provavelmente, são provenientes do intestino das ninfas; e (iii) ser repelente a formigas predadoras e irritante a outro artrópode (baratas). Tomados em conjunto, a espuma produzida por M. fimbriolata serve como uma estratégia termorregulatória e defensiva para as ninfas. Ademais, esta tese serve como base para futuras pesquisas que visam investigar a importância da espuma para o crescimento e desenvolvimento das cigarrinhas.

Ph.D. Faculty of Humanities, University of the Witwatersrand, 2011 / This study analyses the manner in which animals are represented in selected poetry from Malawi, Zimbabwe and South Africa. It discusses the various modes of animal representation the poets draw on, and the ideological influences on their manner of animal representation. It explores the kinds of poetic forms the poets employ in their representation of animals and examines the manner in which ecological or environmental issues are reflected in the poetry. Further, the study determines the extent to which the values expressed in the poems are consistent with, or different from, current ecological orthodoxies and the ways in which the metaphors generated in relation to animals influence the way we treat them. The study shows that in the selected poetry animals occupy a significant position in the poets’ exploration of social, psychological, political, and cultural issues. As symbols in, and subjects of, the poetry animals, in particular, and nature in general, function as tools for the poets’ conceptualisation and construction of a wide range of cultural, political, and philosophical ideas, including among others, issues of justice, identity, compassion, relational selfhood, heritage, and belonging to the cosmos. Hence, the animal figure in the poetry acts as a site for the convergence of a variety of concepts the poets mobilise to grapple with and understand relevant political, social, psychological and ecological ideas. The study advances the argument that studying animal representation in the selected poetry reveals a range of ecological sensibilities, as well as the limits of these, and opens a window through which to view and appreciate the poets’ conception, construction and handling of a variety of significant ideas about human to human relationships and human-animal/nature relationships. Further, the study argues that the poets’ social vision influences their animal representation and that their failures at times to fully see or address the connection between forms of abuse (nature and human) undercuts their liberationist quests in the poetry.

A predação de bovinos (Bos sp.) por onças-pardas (Puma concolor) e onçaspintadas (Panthera onca) foi registrada durante seis anos em uma propriedade rural no Norte do Estado de Goiás, Centro-Oeste do Brasil. A pesquisa teve os objetivos de verificar: (1) quanto bovinos são predados por onças; (2) qual a faixa etária mais predada; (3) se existe sazonalidade na ocorrência da predação e (4) qual sua distribuição espacial em relação aos elementos constituintes da paisagem. A predação foi registrada e quantificada com auxílio dos retireiros e responsáveis pelo manejo dos bovinos, que forneceram em uma ficha o nome do observador, data, retiro, número do pasto, causa da morte, idade e sexo. A predação representou 21,7% (n=309) da mortalidade total de bovinos. Os bovinos predados representaram uma biomassa média anual de 63,8 kg/km², que foi equivalente a 0,4% do estoque médio anual de bovinos. A categoria mais predada foi o bezerro. A predação se associou fortemente à idade dos animais predados, ocorrendo mais com bezerros de até 2 meses e diminuindo gradativamente com o aumento da idade. A predação foi influenciada pela categoria de bovinos (idade e sexo), local e período de nascimentos. Ficou evidente que a predação foi diferente espacial e temporalmente. Dessa forma, um conjunto de medidas preventivas foi sugerido para reduzir a predação de bovinos e garantir a conservação das onças. / Data on cattle predation by pumas (Puma concolor) and jaguars (Panthera onca) has been recorded for six years in a farm in Northern Goiás, Mid-Western Brazil. This research’s main objectives were to determine: (1) the actual proportion of cattle killed by big cats; (2) whether there was a certain age class targeted by those predators; (3) whether the predation fluctuated along the year and (4) the spatial distribution of cattle predation. Data were recorded by employees and cattle managers using forms with the following information (observer’s name, date, id numbers, cause of mortality, age and sex). Predation represented 21,7% (n=309) of the overall cattle mortality. In biomass, kills represented 0,4 % of the farm’ annual stock with 63,8 kg/km². Predation was strongly correlated with cattle’s age with most attacks occurring on calves younger than 2 months old then gradually decreasing the animals get older. Predation was mainly associated with cattle’s age class and location along with the time of the births it occurred. It clearly appeared that cattle predation varied spatially and temporally. We recommended several preventive techniques to be used in order to limit cattle predation in rural farming contexts so as to reduce the conflict between villagers and large felids and thus enhance the last big cats’ conservation.

It can be difficult to disentangle the factors that determine population success in freshwater systems, particularly for organisms with disturbance-resistant life stages like aquatic invertebrates. Nevertheless, the effects of environmental variation and habitat structure on animal population success in wetlands are important for understanding both trophic interactions and biodiversity. I performed two experiments to determine the factors limiting crayfish (Procambarus fallax) and dragonfly (Family: Libellulidae) populations in wetland environments. A simulation of a dry-disturbance and subsequent sunfish (Family: Centrarchidae) re-colonization revealed that crayfish populations are sensitive to sunfish, while dragonfly naiads seemed to be limited by other drying-related factors. A second manipulation revealed that small-bodied fishes and habitat structure (submerged vegetation) shaped dragonfly communities primarily through postcolonization processes. / by Natalie Knorp. / Thesis (M.S.)--Florida Atlantic University, 2013. / Includes bibliography. / Mode of access: World Wide Web. / System requirements: Adobe Reader.

Nest predation can significantly reduce hatchling recruitment in sea turtle populations. This study uses 20 years of data from Canaveral National Seashore, Florida, which has pristine and altered beaches. Chi-square tests were used to determine if secondary predation events were related to the nest's primary depredation event. To determine if human beach use and nest predation are spatially or temporally linked, we ranked human beach use and examined predation frequency across all screened and marked nests (n=40,441). Lastly, I quantified nest predation risk spatially and temporally. I found that primary predation increases the chance of a nest suffering subsequent predation. Primary and multiple predation events occurred with greater frequency in limited use areas and with lowest frequency in moderate use areas. Predation risk decreased by an average of 29.5% from 2000-2008. Nests deposited midseason were 9.8% more likely to be predated than nests deposited early or late. / by Rachel Welicky. / Thesis (M.S.)--Florida Atlantic University, 2010. / Includes bibliography. / Electronic reproduction. Boca Raton, Fla., 2010. Mode of access: World Wide Web.

The red imported fire ant, Solenopsis invicta, is a South American native introduced in Alabama in the early 20th century. This predatory species has rapidly spread throughout the southeastern US and parts of the West Indies, inflicting great ecological and economic damage. For example, Solenopsis invicta is known to attack the eggs and hatchlings of ground nesting birds and reptiles. The ants swarm into the nests attacking hatchlings and diminishing their chance for survival. My thesis research aimed to survey the distribution of ants on sea turtle nesting beaches in South Florida and St. Croix, USVI, and to evaluate the possible threat of Solenopsis invicta and other predatory ants to sea turtle hatchlings. / Includes bibliography. / Thesis (M.S.)--Florida Atlantic University, 2013.

<p><a>Natural enemy ecology strives to integrate the fields of disease ecology and community ecology to forge a broader understanding of how pathogens and predators structure communities. To advance this field, we need a greater emphasis on: 1) quantifying pathogen-mediated effects on community structure and comparing these effects to those observed with predators and 2) determining the interactive effects of combined natural enemies on communities. I conducted a mesocosm experiment designed to assess the individual and combined effects of predators (dragonfly larvae and adult water bugs) and a pathogen (ranavirus) on a larval amphibian community. Additionally, I conducted laboratory experiments to assess whether ranavirus exposure increases the vulnerability of tadpoles to predation. In my laboratory experiments, I found that virus exposure increased predation rates with dragonflies, but not water bugs. For tadpoles in the dragonfly treatments, the probability of survival for virus-exposed tadpoles was 66-77% lower compared to unexposed tadpoles. This data suggests that predators may selectively remove infected individuals from the population, which can enhance the magnitude of the healthy herds effect. I found that the risk level of the predators largely explained effects on the community. For instance, high-risk dragonflies reduce overall survival to 30% whereas low-risk water bugs only reduced survival to 67%. Additionally, I found that virus reduce survival to 62%, which was comparable to effect of the low-risk predator. Interestingly, all three natural enemies influenced community structure (i.e. species relative abundance) in unique ways. These results demonstrate that pathogens can have effects similar to predators on communities, and that natural enemy identity is important when considering impacts on community structure. When predators were combined with the virus, I found that mortality was relatively unchanged from the predator-only treatments suggesting less than additive effects of combined natural enemies. This result was driven by the healthy herds effect; the presence of dragonflies reduced overall infection prevalence in the community to 7% compared to 30% in the virus-only treatment. This effect was observed in the water bug treatments, to a lesser degree, suggesting that predator risk or efficiency contributes the magnitude of the effect. Collectively, my work demonstrates the importance of examining the individual and combined effects of natural enemies on ecological communities.</a></p>

Dans les agroécosystèmes, les réseaux trophiques sont souvent structurés à partir de la plante d’intérêt agronomique, qui permet aux herbivores qui lui sont associés de se développer, notamment les bioagresseurs. La monoculture de bananiers a permis au charançon du bananier (Cosmopolites sordidus) de prospérer. Les larves de C. sordidus se nourrissent exclusivement de bananiers et provoquent leur chute, réduisant fortement le rendement dans la plupart des régions de production. Cette thèse a cherché à élucider la structure et le fonctionnement du réseau trophique de la bananeraie et particulièrement les interactions trophiques qui lient le C. sordidus aux autres espèces. L’objectif appliqué en ligne de mire était de favoriser les prédateurs généralistes pour augmenter la régulation naturelle de C. sordidus.1. Quel est l’effet de l’ajout d’une plante de couverture sur la prédation de C. sordidus ? En utilisant une variété de méthodes – isotopes stables, piégeage, infestation artificielle de bananiers, nous avons testé avec succès l’hypothèse selon laquelle l’enherbement induit, via le développement de proies alternatives, un changement de régime alimentaire des prédateurs généralistes, une augmentation de leurs abondances et une plus forte prédation des oeufs de C. sordidus.2. Quel est la structure du réseau trophique ? Nous avons combiné le séquençage haut-débit (technologie 454) avec le concept de codes-barres à ADN pour identifier les proies présentes dans le contenu stomacal des consommateurs. Nous avons utilisé un marqueur chloroplastique (boucle P6 trnL) pour identifier le bol alimentaire des herbivores, et un marqueur mitochondrial (mini-CO1) pour les prédateurs. Cette approche a permis de détecter des espèces qui n’avaient pas été échantillonnées, d’identifier les prédateurs naturels de C. sordidus au champ, et de quantifier les interactions à l’échelle des populations.3. Comment la structure du réseau trophique peut-elle influencer la régulation de C. sordidus ? Nous avons cherché les différents éléments structuraux (motifs) présents dans le réseau trophique de deux agroécosystèmes bananiers (sur sol nu et sur sol enherbé), et analysé leurs fonctions. Nous avons notamment décelé un motif composé de 4 espèces (2 ressources et 2 consommateurs) qui est représenté en grand nombre par rapport à un modèle neutre de réseau trophique. Ce motif s’est révélé systématiquement déséquilibré en faveur d’une proie, ce qui démontre qu’une distribution asymétrique des forces d’interactions permet de structurer le réseau. L’analyse de la position de C. sordidus dans les motifs décelés a permis de révéler ses interactions préférentielles avec les autres espèces de la communauté.Cette thèse montre comment le couplage de méthodes innovantes et complémentaires permet d’avoir une approche globale du fonctionnement trophique de l’agroécosystème. Les résultats montrent l’importance des ressources primaires (autres que la plante cultivée) sur la structuration du réseau trophique des arthropodes et sur le potentiel de régulation des bioagresseurs. Ce travail illustre également le lien entre la structure globale d’une communauté et l’évaluation des fonctions qui y sont associées / In agroecosystems, food webs are often structured from the crop, which enables the associated herbivores, including pests, to develop. For instance, monoculture in banana fields allowed the development of the banana weevil (Cosmopolites sordidus) populations. Borrowing larvae of C. sordidus cause banana plants topple over, which dampens the yield in most production areas. In this Ph.D. thesis, we attempted to disclose the structure and function of the banana food web, and particularly the trophic interactions that link banana weevil to others species. The applied perspective was to enhance population of generalist predators in order to increase the natural regulation of the pest.1. What is the effect of adding a cover crop on the predation of the pest?By using a variety of methods - stable isotopes analyses, trapping, artificial infestation of banana trees, we successfully tested the hypothesis according to which the addition of a cover crop, by enabling population of alternative preys to develop in the system, induces a change in predator diet, an increase of predator densities, and a greater predation rate on the eggs of C. sordidus.2. How is structured the food web?We combined next generation sequencing (454 technology) with the DNA barcoding concept to identify prey into gut contents of consumers. We used a chloroplastic marker (trnL) to identify the diet of herbivores, and a mitochondrial marker (CO1) for predators. This approach enabled the detection of unexpected species, the identification of the natural enemies of the pest, and the weighting of trophic interactions at the population scale.3. How can food web structure influence pest regulation?We searched structural elements (network motifs) occurring in the food webs of two banana agroecosystems (on bare soil and with cover crop), and we inferred the system functions. We detected the “bi-fan” size-4 motif, which occurred more frequently in the cover cropped food web than in random food webs. Interestingly, this motif was unbalanced for one of the two resources, illustrating the asymmetrical distribution of interaction strengths that shapes food web structure. The analysis of the position of C. sordidus within key motifs revealed its preferential interactions with other species of the community.This Ph.D. thesis emphasizes how linking innovative and complementary methods provides a comprehensive approach of the trophic functioning of the banana agroecosystem. Our results show the importance of primary resources (other than the cultivated crop) on the structure of arthropods’ food webs and on the pest regulation potential. This work also illustrates the link between the community structure and the evaluation of associated functions (i.e. pest regulation)

Os seres vivos estão constantemente influenciando e sendo influenciados pelo meio ambiente. Esta interação pode afetar diretamente o comportamento e a sobrevivência destes seres vivos, incluindo os insetos. O objetivo deste trabalho foi descrever os efeitos de fatores bióticos e abióticos sobre o comportamento e sobrevivência de Spodoptera frugiperda (J.E. Smith, 1797) (Lepidoptera: Noctuidae) e de seus parasitoides de ovos Telenomus remus Nixon 1937 (Hymenoptera: Scelionidae), Trichogramma atopovirilia Oatman & Platner 1983 e T. pretiosum Riley 1879 (Hym.: Trichogrammatidae). Os resultados mostraram que adultos de S. frugiperda realizam suas atividades reprodutivas em períodos bem definidos de sua vida, preferencialmente desde o início até meados da escotofase. Fêmeas de T. remus realizaram parasitismo de ovos de S. frugiperda tanto durante o dia quanto durante a noite. T. atopovirilia foi, dentre as três espécies de parasitoides estudadas, a que apresentou a mais ampla faixa térmica para desenvolvimento ótimo, podendo apresentar elevado potencial de controle de S. frugiperda em regiões quentes como frias. A sobrevivência e os comportamentos de forrageamento de T. remus, T. atopovirilia e T. pretiosum foram afetados pelas competições intra e/ou interespecíficas, sendo os efeitos destas competições peculiares para cada uma das espécies. A competição intra-específica interna afetou a sobrevivência de T. atopovirilia, mas não a de T. pretiosum nem a de T. remus. As competições interespecíficas internas afetaram a sobrevivência destas três espécies, sendo a ordem de parasitismo e o intervalo entre as oviposições determinantes para o resultado da competição. Observou-se emergência das duas espécies de Trichogramma a partir de um único ovo multiparasitado. A espécie T. atopovirilia, dentre as três espécies estudadas, foi a que apresentou maior probabilidade de vencer na competição interna interespecífica. Estes resultados sugerem que pistas químicas (ex.: feromônios) liberadas por adultos de S. frugiperda podem ser utilizadas como cairomônios por fêmeas de T. remus durante o período noturno, viabilizando o fenômeno de forésia, e que a temperatura e competição afetam a sobrevivência e/ou o comportamento de T. remus, T. atopovirilia e T. pretiosum, devendo ser consideradas na escolha da espécie ou combinação de espécies a ser liberada em campo visando ao controle populacional de S. frugiperda. / Living beings often influence and are influenced by the environment. Such interactions can directly affect the behavior and survivorship of insects. The aim of this study was to describe the effects of biotic and abiotic factors on the behavior and survivorship of Spodoptera frugiperda (J.E. Smith, 1797) (Lepidoptera: Noctuidae) and its egg parasitoids Telenomus remus Nixon 1937 (Hymenoptera: Scelionidae), Trichogramma atopovirilia Oatman & Platner 1983, and T. pretiosum Riley 1879 (Hym.: Trichogrammatidae). The results showed that adults of S. frugiperda perform reproductive activities during well-defined periods of their life, preferably from the beginning until the middle of scotophase. Females of T. remus parasitized S. frugiperda eggs in both photophase and scotophase. T. atopovirilia was the species with the widest temperature range for optimal development, and therefore with a high potential for controlling S. frugiperda populations in different temperature conditions. Survivorship and foraging behaviors of T. remus, T. atopovirilia, and T. pretiosum were affected by intra- and/or interspecific competition, with particular effects on each parasitoid species. Intrinsic intraspecific competition affected T. atopovirilia survivorship, but did not affect T. pretiosum or T. remus. Intrinsic interspecific competition affected survivorship of all three parasitoid species. The parasitism sequence and oviposition interval were critical for the result of this competition. Emergence of two Trichogramma species from a single multiparasitized host egg was observed. Of the three parasitoid species, T. atopovirilia showed the highest likelihood of winning in intrinsic interspecific competition. These results suggest that chemical cues (e.g., pheromones) released by adults of S. frugiperda can be used as kairomones by females of T. remus during the scotophase, enabling the phenomenon of phoresy. Moreover, temperature and competition affect the survivorship and/or behavior of T. remus, T. atopovirilia and T. pretiosum and should be considered when selecting the species or combination of species for field release to control S. frugiperda populations.

The chevron skink (Oligosoma homalonotum) is one of the largest, yet least observed skink species in New Zealand. The species was thought to have once been widespread in Northern New Zealand, however currently it is only found on Great Barrier and Little Barrier Islands. Great Barrier Island is the apparent stronghold for the species although it appears to be in decline there, despite a net increase in habitat. Recent studies have increased the understanding of the general ecology of the species, however little is known about the threats to the survival of this species. This study had two main objectives; the first was to establish if rats are a threat to chevron skinks, and the second was to increase current knowledge of the species ecology. The research was undertaken in an area of extensive rodent control (Glenfern Sanctuary) and an adjacent unmanaged reserve in Port Fitzroy, on Great Barrier Island in 2008. The first objective of this study involved confirming that rat densities in the treatment (Glenfern Sanctuary) were sufficiently different to allow meaningful comparisons of chevron skink population characteristics between sites. This was achieved by determining absolute rat densities using Zippin’s removal method at four sites, and correlating these with a relative abundance measure (tracking rates) to give confidence in the observed trends. Rat densities were high (1.94 - 3.00 rats ha-1) in the control, and low (0.00 and 0.06 rats ha-1) in the treatment sites, and these correlated well with tracking rates. In light of these clear differences between the treatment and control, the population structure and condition of chevron skinks were compared between sites. The population structure showed erosion of juvenile and sub-adult size categories, which indicated differences in vulnerabilities between size categories. Physical evidence of failed rat predation was also observed in adult skinks in the unmanaged control, which confirmed that rats were interacting with chevron skinks. Although the adults survived the attacks they suffered injuries including eye damage, punctures, cuts and tail loss. Smaller skinks would be unlikely to survive such attacks due to the severity and scale of the injuries, supporting the assertions of the population structure that smaller skinks may be more vulnerable than adults. The extent of tail loss was converted to a condition index to determine if failed rat predation was more widespread in the population, than was observed by conspicuous injuries. This condition index (body-tail condition index) was stable through all size categories in the treatment, but significantly reduced in adults in the unmanaged sites. That there was no reduction in the condition of smaller skinks in the unmanaged control sites despite high rat densities suggests that interactions between rats and smaller skinks are fatal, and thus not represented in the data. Nine chevron skinks were radio-tracked to determine habitat use, home range and ranging behaviour. Habitat use of chevron skinks was similar to a previous study and demonstrated that trees, crevices and logs were important refuge sites. Chevron skinks were more likely to be found at sites with trees, crevices and debris dams. Chevron skink home ranges indicated that adults moved further away from streams than previously anticipated at this time of year, and skinks demonstrated site fidelity. There was also overlap in home ranges between individuals, and skinks with overlapping home ranges shared common refuges. During flooding events, chevron skinks exhibited an arboreal response that appears to be a behaviour specific to stream associated animals, which allows them to avoid being taken by floodwaters.