The mobility of carabid beetles in the field has been studied by a number of researchers in recent years, but the small scale movements are still poorly understood. The populations of five species of carabid beetles living in a Surrey oakwood were therefore investigated using pitfall trapping and individual marking techniques over a period of three years. Five aspects of the complications associated with the interpretation of pitfall trapping and mark-release-recapture studies were investigated: (i) baiting of the traps by the catch itself, (ii) escape ability of captured beetles, (iii) changes in behaviour following overlong procedures between capture and release, (iv) density effects produced in trapping, and (v) effects of marking procedures on behaviour and survival. No effects could be demonstrated for (i), (iv) and (v). However, the escape rate in Nebria brevicollis was shown to be very high, and the behaviour of the same species affected by the length of time between capture and subsequent release. More than 3000 recaptures of marked beetles were made. Survival into a second breeding season was found to be commonplace in all five species; a few even entered a fourth. The distributions of the beetles within the study area were aggregated, particularly so in Nebria, where it was also shown that the beetles tend to remain in the areas where they are in the highest densities. Distributions changed little with season. Peak displacement rates were associated with the breeding seasonin Nebria but, whereas this fell off with the onset of winter in first season beetles, the level remained high in second season individuals. Pterostichus madidus exhibited a significant lack of displacement with time, except with males during the breeding season. Greatest activity and dispersal was found in August in first season males, but June and July with second season. Abax parallelepipedus beetles were found to be most active early in the season. Very few beetles of the species were found to disperse 100 metres or more within the study area. The concept of home range was examined in relation to ground beetles. Site attachment could not be demonstrated in any species, although other aspects of the trapping results indicated some form of home ranging behaviour.

No description available.

Understanding and predicting animal movements is of crucial importance for the conservation and management of natural resources. Grasshoppers are ecological indicator species used to monitor the spatio- temporal changes, to help reduce further loss of biodiversity on open grasslands. However, their current decline on European landscapes as a consequence of intense agricultural practices has elicited the need to understand all aspects of their ecology especially their movement on these highly fragmented landscapes. With the use of a mesocosm, a mark and re-sight study was conducted in the Poitou Charentes Region of Western France, to investigate the movement dynamics of three widespread species in that area. With emphasis placed on the determinants of their rate and scale of movement in addition to the influence of individual behavioural trait variations on dispersal plasticity. Net square displacement and mean squared displacement was used to quantify rate and pattern of movement. Two sub populations were identified and classified as settled and yet to settle sub- population. Poisson regression analysis and generalized linear models were used to test significance of interactions between grasshopper species and microhabitat constituents. Average distance travelled by re-sighted individuals ranged from 3.50metres to 18.66 metres. However the variation in average distance estimated for each of the species, arose from species specific interactions with micro habitat conditions especially vegetation functional class found within the quadrat. Inter specific differences due to the possession of morphological correlates with dispersal; large body size and wing development, explained variation in magnitude of dispersal especially between C.dorsatus and P.giornae. However the rate of displacement exhibited by E.elegantulus suggest that possession of these traits in relation to proximity to food resources influences dispersal kernel. The study was conducted during grasshopper breeding season when sex specific reproductive traits were likely to be more apparent. As a result of this, average distance travelled by male individuals exceeded that of females, but then these differences were not statistically significant.

There are some references on the study of morphology of the Homoptera in which Cicada has been taken as a basis for the generalised structure. In the sub-order Sternorhyncha paylla has been studied, but there are hardly any references directly dealing with the Aleurodidae or any particular species except the general morphological and anatomical features described by Quaintance and Baker (l913) in their "Classification of the Aleurodidae, Part I.". No one has studied the structure of any of the British species.

Anopheles gambiae is a major vector of malaria in sub-Saharan Africa. Given the widespread emergence of pesticide resistance in Anopheles gambiae populations, vector control programs involving the release of sterile males or genetically-modified male mosquitoes designed to diminish malaria transmission are eliciting renewed interest. The success of such mosquito release projects depends on the ability of released males to effectively mate and transfer sperm to wild females. Here, firstly we investigated the interactive effect of the environmental factor hydric stress and adult mosquito phenotypic quality on male and female reproductive success. Secondly, we studied the impact of colonization and genetic modification on potential correlates of reproductive success by comparing sperm quality and sexual organs in the wild strains with transgenic and colonized strains. We then experimentally tested for the potential effects of inbreeding depression on reproductive traits by creating hybrid males from inbred colonized strains. The quality of these 'Super males' was assessed by comparing sperm quality, testes and accessory gland sizes, and estimating the quantity of Plugin and Transglutaminase proteins in their accessory glands. Finally, we assessed the reproductive performance of Super males by estimating the amount of accessory gland protein transferred to females after overnight mating and estimating female fecundity and number of larvae produced. The results underline the importance of female phenotypic quality as determinant of mosquito reproductive success. Inbreeding associated with the colonization and/or genetic modification processes strongly affects sperm length. In contrast, offspring of field-collected females strain have smaller testes and larger accessory glands than older colonized strains. Super males had a good sperm quality. Importantly, the present study suggests that Super males could represent a way to improve male’s reproductive quality under laboratory conditions.

No description available.

Current methods for assessing the health of insects and their colonies are carried out by researchers making dissections on individual insects (which inevitably kills them) or making visual inspections of colonies and then documenting their observations. For colonies, researchers look for behavioural signs which indicate healthy individuals where foragers are regularly bringing in resources or in weak colonies, where there are fewer foragers working with a more lethargic and less purposeful manner. These methods are prone to large errors and they kill many insects in the process. The research detailed in this thesis addresses the subjective and destructive nature of these methods. This thesis also describes new methods using x-ray CT to develop and adopt protocols to accurately study insects non-invasively. Chapter one covers the current literature on tomography and some background on the different CT methods. Chapter two gives a thorough description of the new methods being developed to study insects non-invasively and details techniques that can be adopted by researchers who require non-invasive approaches to their work. Chapter three describes in detail three examples of research that has been conducted on locusts, ladybirds and butterflies to non-invasively study aspects of their morphology. The methods described maintain the integrity of the specimens for future use if so required. Chapter four covers a specific example of a fine detail study on plasticity of the honeybee brain using X-ray MicroCT and discusses the potential for live scanning to observe brain plasticity in insects. Chapter five extends the work from chapter two to show the usefulness of CT for studying insect behaviour by documenting and describing previously unreported honeybee storage behaviour. Chapter six draws conclusions from the other chapters and discusses future research.

Visually guided navigation presents the perfect arena for studying the relationship between brain, body and environment and the behaviour which emerges from their interaction. It is a behaviour seen across the animal kingdom, from desert ants to humans, offering the possibility of common underlying computational principles. In addition, it represents an important applied problem: how to get robots to navigate reliably in situations where other kinds of information are lacking or absent. This thesis examines the problem of visual navigation in insects at different levels of abstraction using computational modelling, showing the power of this approach in describing and explaining insect behaviour, with a focus on image-based homing methods. It begins with an examination of an exploratory behaviour performed by naive foraging ants, known as ‘learning walks', and how the relationship between the shape of the learning walk and the visual form of the environment together determine homing success. I then proceed to look at the information carried by the visual receptive fields associated with a small number of neurons (of two classes) in Drosophila, showing that this corresponds to behavioural performance, without requiring any additional black boxes. Finally, I show that simple insect-inspired algorithms also perform well in different applied contexts, such as a flying agent and as a real-world visual compass. The contribution of this thesis is to show the value of computational modelling both in gaining an understanding of complex behaviours, particularly where many variables make more conventional analysis impossible, and in designing real-world applications.

The planthopper Prokelisia marginata Van Duzee is native to the eastern coast of North America, where densities on its foodplant, the cordgrass Spartina alterniflora, frequently exceed several thousand per square metre. It has little impact on its host plant in its native range where both species have co-evolved, however where the plant has been introduced and has had no recent exposure to the planthopper, it has a major impact and has been trialled as a biological control agent. P. marginata was recorded for the first time in Britain in 2008, where it feeds primarily on the widespread S. anglica, itself listed as one of the world's 100 worst invasive species, as well as its progenitors S. alterniflora, S. maritima and S. x townsendii. P. marginata appears to be in the successful early stages of invasion in Britain, having already spread extensively. Significantly outnumbering all other saltmarsh arthropod groups, it is benefitting from partial natural enemy escape, and a high proportion of macropterous individuals in all populations indicates strong potential for further range expansion. Utilising both glasshouse and field manipulations, I show that exposure to P. marginata has a significant negative impact on S. anglica, an interaction which has the potential to destabilise Britain's important saltmarsh habitat. I suggest that the four host species that occur in Britain represent a ‘gradient' of shared co-evolutionary history with the planthopper. I show that, whilst all species are negatively impacted by P. marginata exposure, S. alterniflora, the species with which it shares the longest co-evolutionary history, is the least affected. I further show that P. marginata exhibits a preference for, and performs better on, S. anglica. As S. anglica is by far the most abundant of the four Spartina species in Britain, these results suggest P. marginata may be undergoing rapid evolution in its new range to take advantage of this widespread host species, thereby maximising its potential for further range expansion.

Understanding life history variation in insects requires an assessment of how resources are allocated between reproductive and somatic traits. Associated data are not only a potential indicator of species adaptation, but also of environmental influences on fitness. So far, however, there is a dearth of data on factors affecting resource allocation, in particular in real environments. Using an integrative nutrient assay protocol, this study assessed the effects of body size and environmental conditions on resource allocation strategies in terrestrial and aquatic semelparous insects: the indian mealmoth, Plodia interpunctella under laboratory conditions, and two caddisfly species (Hydropsyche siltalai and Rhyacophila dorsalis) in the field. In Plodia interpunctella, larger females had higher potential lifetime fecundity due to their prolonged lifespan, while smaller females maintained greater initial egg loads and a shorter life-span. Assays revealed that current reproduction requires greater nutrient allocation in somatic and reproductive tissue, illustrating potentially fundamental factors underlying reproduction-longevity trade-offs. Field studies showed how trichopteran larvae have species-specific responses to physicochemical conditions located along an altitudinal gradient (20 m - 230 m asl) in the River Usk. Nutrient allocation in Rhyacophila dorsalis did not differ between upstream and downstream sites. In contrast, upstream Hydropsyche siltalai emerged with greater nutrient reserves consistent with early reproduction while those in warmer downstream environments must reallocate resources for somatic maintenance reducing available resource for reproduction. Consistent with this result, translocation of late instar H. siltalai over a thermal gradient (1.5 - 4.5 °C) showed how thermal exposure can affect adult fitness by reducing body size and increasing nutrient allocation for somatic maintenance. These results show how insects adjust nutrient balance for reproduction and survival under different circumstances. The most significant result is that global warming might reduce body size and advance reproduction in some species with consequences for fitness. This is proposed as an area ripe for further study to understand the evolutionary consequences of global change.