Hoverflies are important for their roles in ecological and environmental services, and are also charismatic species of conservation interest in their own right. Almost half of all hoverflies are saprophages, which are organisms that feed on dead or decaying organic matter, and these include saproxylic species that depend on deadwood. Deadwood and its associated community are a rich source of forest biodiversity and are fundamental to forest function, but due to poor management, many saproxylics are threatened or endangered, and techniques for conserving saproxylic species are poorly developed. In this thesis I study the ecology and conservation management of an endangered UK saproxylic fly, the Pine hoverfly, Blera fallax (Linnaeus) (Diptera, Syrphidae) and the dispersal ability of the similarly endangered Aspen hoverfly, Hammerschmidtia ferruginea (Fallén) (Diptera, Syrphidae). My main goals were to clarify methods to support their recovery in active programmes of species conservation in Scotland, UK. For B. fallax, this included experimenting with habitat creation techniques, investigating the best conditions for larval growth and assessing competition effects. In addition, I evaluated the genetic variability of the remaining population in Scotland by comparing it with one in Europe to determine whether genetic constraints may limit recovery. For H. ferruginea, I determined dispersal ability with field experiments involving mark and recapture techniques. By cutting holes at the surface of stumps of Pinus sylvestris, breeding habitat was created artificially for B. fallax at the remaining known locality for this species in the UK. Over 4 years, 81 % of holes were colonized by B. fallax, and by up to six other saproxylic syrphid species. The most successful holes were those cut into the heartwood, seeded with pine chips and sawdust and partially covered, as indicated by a combination of field occupancy monitoring and lab growth experiments. Observations of larval morphology and behaviour within rot holes revealed specializations that largely segregate the species in both time and space, and may mitigate interspecific competition between B. fallax and three more common syrphid species. I further demonstrated that B. fallax has a life history that features facultative semivoltine development, which may be a bet-hedging strategy to cope with fluctuating levels of larval food. Fifty B. fallax larvae were successfully reared and bred in captivity and from these, 430 descendent laboratory reared larvae and adults were released across three relocation sites. After initial success at the first re-location site when a new generation of larvae appeared in holes in 2010, a population crash at all sites occurred in the following year, possibly caused by adverse weather conditions. This disappointing result highlights the vulnerability of small populations to stochastic events, and means that survival of B. fallax may now depend on those larvae that are semivoltine, supplemented by animals currently being reared in captivity. My genetic analyses revealed similarly troubling information that highlights the precarious existence of B. fallax in Scotland: compared with a population in Sweden, Scottish B. fallax had significant less neutral genetic variation, and showed signs of a recent and severe bottleneck that reduced the effective population size to just 12 (CI: 0 - 266) individuals at some point in the last 200 years. Mindful of these challenges, I exploit my new data on the ecology and life history of B. fallax and combine it with techniques for captive rearing and for monitoring the genetic health of B. fallax into specific protocols and general prescriptions for the on-going recovery and management of this species. In order to assess the dispersal ability of H. ferruginea (and therefore its potential for recolonizing newly created habitat), in May to July over two years, adults were marked and released from a central point and subsequently monitored at the breeding site, decaying aspen wood Populus tremula, where adults tend to assemble for mating and oviposition. Adults were resighted visiting logs of decaying aspen set out at 1 km intervals along transects up to 7 km away. Up to 10 % of released individuals were resighted up to 5 km from the central release point. Most dispersing individuals (68 %) were resighted at 1 km, which I propose as the optimal distance for managing aspen for this species. Both of these hoverflies are case studies of techniques for recovering endangered saproxylic flies. Overall, my findings greatly increase fundamental knowledge of the ecology and natural history of these flies, and clarify some of the practical approaches that will be required in their conservation.

One of the greatest problems for sub-Saharan Africa is shortage of epidemiological data to support planning for provision of adequate public and animal health services. The overriding challenge is to provide the necessary resources to facilitate the process of regular data collection in support of disease surveillance and vector monitoring across target regions. Due to such circumstances, there is currently an increasing interest towards devising cheaper but yet significantly reliable means for availing the needed epidemiological and vector data for planning purpose. This study comes as a contribution towards solving such challenges. The study has three research components starting with a review of past Uganda national tsetse and trypanosomiasis control efforts as a means towards appreciating the dynamics of controlling the vector and disease. This is an analysis of what was applied, what worked, what didn't, and why it didn’t as linked to the broader vector and disease control system. Secondly through the use of remote sensing, geographical information systems and global positioning technologies tsetse species were sampled within Lake Victoria Basin. Only two species of tsetse were trapped, G. f. fG. f. fuscipes which was widely distributed across the surveyed area, and G. Pallidipes which was detected in a few isolated locations close to the border with Kenya in Eastern Uganda. The analysis of land cover with tsetse findings showed an important association between G. f. fuscipes and particular vegetation mosaics. Unfortunately, while the results are highly informative, approaches for data collection such as this one are costly and unlikely to be sustained by the already over-burdened health systems in the low developed countries of Africa. The third and main part of this study investigates, demonstrates and delivers the possibilities of applying spatial epidemiological modelling techniques to produce both tsetse distribution and abundance maps. Four spatial and non-spatial regression models (Logistic, Autologistic, Negative binomial and Auto-negative binomial), were constructed and used to predict tsetse fly presence and tsetse fly abundance for the study area. The product is an improved understanding of association between environmental variables and tsetse fly distribution/abundance and maps providing continuous representations of the probability of tsetse occurrence and predicted tsetse abundance across the study area. The results indicate that tsetse presence and abundance are influenced differently. Tsetse abundance is highly determined by river systems while tsetse presence is majorly influenced by forested landscapes. Therefore, efforts to control trypanosomiasis through vector control in the Lake Victoria basin will call for delineation of such clearly identified high tsetse accumulation zones for targeted tsetse control operations. This will ensure optimum utilization of the scarce resources and above all contribute to the protection of humans and animals against trypanosomiasis infection.

The ability to adhere to the extracellular matrix (ECM) is critical for numerous cell types and tissues including epithelia and muscle. Cell-ECM adhesion is primarily mediated by integrins which provide a direct link between the ECM and the actin cytoskeleton. Integrin adhesions are frequently associated with a core of 60 different proteins (integrin-associated proteins, IAPs). Integrins are required for muscle attachment and in Drosophila, loss of integrins and several IAPs results in embryonic lethality and muscle detachment. However, the IAPs FAK, RSU1, tensin, vinculin and zyxin are not required for viability or embryonic muscle attachment. Furthermore, FAK, RSU1, tensin and vinculin have been observed to localise to muscle attachment sites in Drosophila, indicating that they have some function in muscle attachment. Unlike FAK, RSU1, tensin and vinculin, it was not previously known whether zyxin is expressed in Drosophila muscles. To test this, I generated a genomic zyxin-GFP construct that should contain most of the endogenous zyxin promotor. The genomic zyxin-GFP construct was not observed at muscle attachment sites, suggesting that it is not normally expressed in muscle. I wished to know whether FAK, RSU1, tensin and vinculin are required for muscle function. Various behavioural assays were employed to test for muscle function in larvae and adult flies. The results suggest that larval muscle function was normal in flies lacking these IAPs, but that adult muscle function might be impaired, although it proved difficult to demonstrate a clear functional defect. I then tested whether the IAPs FAK, RSU1, tensin and vinculin are required for normal morphology of adult muscles, focusing on the adult indirect flight muscles (IFMs). The IFMs are fibrillar muscles which attach to the cuticle via specialised epithelial cells known as tendon cells. At the end of the myofibril, where the myofibril attaches to the tendon cell, is a dense region of actin and IAPs known as the modified terminal Z-band (MTZ). I have found that the MTZ is not a homogenous zone of proteins, but is instead organised into at least three distinct layers. Because of the similarity between the structure of the MTZ with that of a hand, I refer to the layers as ‘fingers’, ‘palm’ and ‘wrist’. I discovered that the IAPs FAK, RSU1, tensin and vinculin are each required for the proper structure of the MTZ in unique ways. The fingers were elongated in IFMs lacking FAK, RSU1, tensin or vinculin, while the palm was disrupted in IFMs lacking RSU1, tensin or vinculin. Finally, I was intrigued by the enrichment of the actin-binding protein filamin/Cheerio in the palm and wished to know if it is required for palm function. Deletion of the C-terminus of filamin/Cheerio resulted in a reduction in palm length. Filamin/Cheerio is a mechanosensitive protein which exists in a closed and open conformation. I found that filamin/Cheerio must be open in order to help form a normal palm. Furthermore, vinculin is required to convert filamin/Cheerio from and closed to an open filamin/Cheerio state so that it can perform its function in the palm.

In this thesis I investigated the genetic basis of several behaviours to answer questions surrounding the evolution and mechanistic basis of behaviour. Firstly, I took a single-gene approach to investigate the influence of fruitless (fru) on the courtship behaviour of Drosophila. fru is an alternatively-spliced transcription factor that is necessary for the production of male sexual behaviours, and has also been implicated in producing species-specific differences in courtship song. I investigated the patterns of selection acting on fru at the sequence level and found that positive selection was restricted to the alternatively spliced exons of fru. From this I hypothesised that the positively selected changes in fru would contribute to species-specific differences in courtship song. To test this I examined how isoform-specific fru loss-of-function mutants influence courtship song, and generated “species-swapped” flies whereby regions of fru that showed evidence for positive selection were transferred from four species of Drosophila, into D. melanogaster. Contrary to prediction, I found flies that lacked isoforms containing positively selected regions did not show any differences in courtship song. Unfortunately “species-swapped” flies were not generated in time to examine phenotypes and neuroanatomy as intended. Next, I examined the genetic basis of cold acclimation in two species of Drosophila using a transcriptomic approach. I found that the genes differentially expressed in response to cold acclimation were largely different in each of the species; however, the biological processes they were involved in were broadly similar. Finally, I investigated the transcriptomic changes associated with parental care in the burying beetle Nicrophorus vespilloides to determine if males and females alter the genes they express when parenting alone versus with a partner. I found that males greatly reduced their transcriptional response when parenting with a partner, suggesting they reduce the care they provide when present with a female.

Ο δάκος της ελιάς, Bactrocera oleae, αποτελεί το κυριότερο παράσιτο του καρπού της ελιάς. Λόγω της μεγάλης οικονομικής σημασίας της ελιάς, ιδιαίτερα για τις Μεσογειακές χώρες, ο αποτελεσματικότερος έλεγχος του εντόμου αυτού είναι απαραίτητος. Η εφαρμογή μεθόδων ολοκληρωμένης διαχείρισης του παρασίτου αυτού, μεθόδων δηλαδή φιλικών προς το περιβάλλον, επιβάλλει την καλύτερη γνώση της βιολογίας του και ιδιαίτερα της γενετικής και της γενετικής δομής των φυσικών πληθυσμών του. Στα πλαίσια αυτά, στόχος της παρούσας μελέτης ήταν η ανάπτυξη στο δάκο DNA δεικτών, των μικροδορυφόρων, οι οποίοι είναι άφθονοι στα γονιδιώματα και επιπλέον υψηλά πολυμορφικοί, για την ανάλυση φυσικών πληθυσμών του. Για την απομόνωση των μικροδορυφορικών δεικτών ακολουθήθηκαν τρεις διαφορετικές στρατηγικές: η κατασκευή και διαλογή γονιδιωματικών βιβλιοθηκών, η κατασκευή εμπλουτισμένων σε μικροδορυφόρους βιβλιοθηκών και ο έλεγχος ζευγών εκκινητών που είχαν σχεδιαστεί για την ενίσχυση μικροδορυφόρων στα συγγενικά είδη B. tyroni και C. capitata για το κατά πόσο ενισχύουν τις αντίστοιχες περιοχές και στο γονιδίωμα του εντόμου B. oleae (cross-species amplification). Από τις βιβλιοθήκες απομονώθηκαν συνολικά 69 κλώνοι που περιείχαν μικροδορυφόρους. Ακολούθησε ο σχεδιασμός ζευγών εκκινητών στις μοναδικές περιοχές που περιβάλλουν τους μικροδορυφόρους. Συνολικά σχεδιάστηκαν 42 ζεύγη εκκινητών. Οι εκκινητες αυτοί ελέγχθηκαν για το αν ενισχύουν το αναμενόμενο προϊόν. Ο έλεγχος έγινε με PCR και ηλεκτροφόρηση των προϊόντων σε πήκτωμα αγαρόζης. Παράλληλα ελέγχθηκαν είκοσι ζεύγη εκκινητών που είχαν σχεδιαστεί για μικροδορυφόρους του εντόμου B. tryoni και 42 ζεύγη εκκινητών που είχαν σχεδιαστεί για μικροδορυφόρους του εντόμου C. capitata. Οι τρεις διαδικασίες απομόνωσης έδωσαν συνολικά 67 λειτουργικά ζεύγη εκκινητών. Στη συνέχεια ελέγχθηκε μέσω PCR ο πολυμορφισμός των εκκινητών αυτών και το αν ενισχύουν διακριτά αλληλόμορφα, με μήτρα DNA γενετικό υλικό εννέα ατόμων. Τα προϊόντα της PCR αναλύθηκαν σε πήκτωμα ακρυλαμιδίου. Από τα 49 ζεύγη εκκινητών που ελέχθησαν, τα 28 έδωσαν πολύ καθαρό σήμα, ενώ τα 25 από αυτά βρέθηκαν πολυμορφικά. Μια πρώτη πληθυσμιακή ανάλυση έγινε με τη χρησιμοποίηση 24 από αυτούς τους δείκτες για την ανάλυση μικρού δείγματος ατόμων. Βασικός σκοπός της ανάλυσης αυτής ήταν να ελεγχθεί η ποιότητα των δεικτών και οδήγησε στον αποκλεισμό έξι δεικτών: ο ένας ήταν μονομορφικός, ένας δεύτερος έδειξε ασθενή ενίσχυση και μικρή επαναληψιμότητα και άλλοι τέσσερις εμφάνισαν απόκλιση από την ισορροπία κατά H-W, πιθανότητα λόγω της παρουσίας null αλληλομόρφων. Δώδεκα από τους υπόλοιπους δεκαοκτώ δείκτες χρησιμοποιήθηκαν για μια εκτεταμένη ανάλυση των πληθυσμών του δάκου στην Ευρωπαϊκή πλευρά της λεκάνης της Μεσογείου. Αναλύθηκαν δεκαεννέα δείγματα, μεγέθους εννέα ως πενήντα ατόμων, από έξι διαφορετικές χώρες (Ελλάδα, Κύπρος, Τουρκία, Ιταλία, Ισπανία και Πορτογαλία). Η ανάλυση αποκάλυψε σχετικά μικρές γενετικές αποστάσεις, που έδειχναν όμως μια στατιστικά σημαντική διαφοροποίηση σε τρεις υποπληθυσμούς. Ο πρώτος αποτελείτο από τα δείγματα της Κύπρου, ο δεύτερος από τα δείγματα Ελλάδας, Τουρκίας και Ισπανίας και ο τρίτος από τα δείγματα της Ιβηρικής χερσονήσου. Οι στατιστικές αναλύσεις που έγιναν έδειξαν τη σημαντική επίδραση της γεωγραφικής απόστασης στη δημιουργία αυτών των ομαδοποιήσεων. Οι τρεις αυτές ομάδες χαρακτηρίζονται από διαφορά και στο επίπεδο του πολυμορφισμού, εμφανίζοντας μια καθαρή μείωσή του από την Ανατολή προς τη Δύση. Η μείωση αυτή είναι στατιστικά σημαντική και με βάση την υπόθεση ότι η πορεία εποικισμού ενός είδους συνοδεύεται από μείωση του πολυμορφισμού, δίνει σημαντικές ενδείξεις για μία προς Δυσμάς πορεία εποίκισης του είδους στον Ευρωπαϊκό χώρο, με πρώτο κέντρο εξάπλωσης την Ανατολική λεκάνη της Μεσογείου. Τα πειράματα δια-ειδικής ενίσχυσης έδειξαν στενές φυλογενετικές σχέσεις των ειδών που εξετάστηκαν και κυρίως μεταξύ B. tryoni - B. oleae και B.oleae - C. capitata. Τα πειράματα αυτά υποστηρίζουν την χρησιμότητα των δεικτών που απομονώθηκαν σε ενδεχόμενες φυλογενετικές μελέτες στα είδη αυτά, καθώς και σε άλλα συγγενικά είδη. Η εύρεση ενός μεγάλου ποσοστού συντηρημένων μικροδορυφόρων σε είδη που έχουν διαχωριστεί εδώ και πολλά εκατομμύρια χρόνια ενισχύει την υπόθεση ότι οι μικροδορυφόροι δεν είναι γενετικό υλικό χωρίς ρόλο (junk DNA), αλλά επιτελούν συγκεκριμένες λειτουργίες στο γονιδίωμα. Η ανάλυση πολυμορφισμού που έγινε στις ατομικές διασταυρώσεις ατόμων από εργαστηριακούς ήταν ιδιαίτερα ενθαρρυντική. Ο υψηλός πολυμορφισμός που βρέθηκε δείχνει την δυνατότητα χρησιμοποίησης τους και στη γενετική χαρτογράφηση του είδους. / The olive fruit fly, Bactrocera oleae, is the main pest of the olive fruit. Because of its great economic importance, especially for the Mediterranean countries, there is a need for a more effective control method. The application of an integrated, environmental friendly, management of this pest requires a better knowledge of its biology and of the genetic structure of its natural populations. The aim of the present study was the development of DNA microsatellite markers for the analysis of the natural populations of the olive fruit fly. These markers are abundant in the genome of any species studied so far and highly polymorphic. Three different strategies were used for the isolation of microsatellite markers. The first was the construction and screening of genomic libraries of the insect, the second was the construction of genomic libraries, enriched for microsatellites and the third was the use of primer pairs that were designed for the amplification of microsatellite markers in the closely related species Bactrocera oleae and Ceratitis capitata(cross-species amplification). A total of 69 microsatellite containing clones were isolated from libraries. The next step was the design of primer pairs in the microsatellite flanking sequences. A total of 42 primer pairs was designed and tested for their abillty to amplify the expected product. Test was performed through PCR and analysis of the PCR products through electrophoresis on agarose gel. Twenty primer pairs designed for the amplification of Bactrocera tryoni’ s microsatellites and 42 primer pairs designed for the amplification of Ceratitis capitata microsatellites were also tested. All three strategies gave 67 primer pairs that amplified the expected product. The degree of polymorphism of these primer pairs and their ability to amplify easily resolvable alleles was tested through PCR with DNA template of nine individuals. PCR products were analysed through polyacrylamide gel electrophoresis. Twenty eight out of the 49 primer pairs tested produced clear bands and twenty five of them were polymorphic. A small scale population analysis was then performed, using tventy four of the markers available. The main purpose of this analysis was to demonstate the quality of the markers and lead to the exclusion of six markers: one of them was monomorphic, another didn’t show reproducible results and four more showed deviations from H-W equilibrium, probably because of the presence of null alleles. Twelve of the remaining loci were used in a large scale analysis of B. oleae’s populations in the European part of the Mediterranean basin. Nineteen samples, varying from nine to fifty individuals, were analysed. These samples were collected from six different countries (Greece, Cyprus, Turkey, Italy, Spain and Portugal). The analysis revealed relatively low genetic distances, which, however, demonsrated a statistically important differentiation of the samples in three subpopulations. The first consisted of the samples from Cyprus, the second of the samples from Greece, Turkey and Italy and the third of the samples from the Iberian Peninsula. The statistical analyses performed showed the statistically important contribution of geographic distance to the generation of genetic distance. These three groups of samples also demonstrate a clear loss of polymorphism towards West. This loss is statistically important and, if we take into account the hypothesis that the colonization process of a species is followed by a loss in polymorphism, it suggests a colonization process of the olive fruit fly towards West in the European part of the Mediterranean basin, with a first expansion area in the Eastern part of the Mediterranean basin. Cross-species amplification experiments indicate close phylogenetic relationships among the species studied, mainly between B. tryoni-B. oleae and B. oleae-C. capitata. These results support the usefulness of the markers isolated in phylogenetic studies in these species, as well as in other, closely related species. The identification of a high percentage if conserved microsatellites in species that have been well separated for millions of years is in agreement with the hypothesis that microsatellites are not useless genomic regions (junj DNA) but they perform specific functions in the genome. Polymorphism analysis in the crosses of individuals from laboratory strains was very encouraging. The high degree of polymorpism showes that they can be used in genetic mapping of the species

Immune activation is generally acknowledged to be costly. These costs are frequently assumed to result from trade-offs arising due to the reallocation of resources from other life-history traits to be invested in immunity. Here, I investigated the energetic basis of the costs associated with immune activation in Drosophila melanogaster. I found that immune activation significantly reduced fly fecundity (45%) and also caused a decline in metabolic rate (6%) but had no effect on body weight. To understand the factors behind reduced fecundity and metabolic rate I measured feeding and found that food intake was reduced by almost 31% in immune-challenged D. melanogaster. These findings suggest that fecundity costs of immune activation result not from the commonly accepted resource reallocation hypothesis but probably because resource acquisition is impaired during immune responses. The individuals of any animal population generally vary greatly in their ability to resist infectious disease. This variation arises due to both environmental heterogeneity and genetic diversity. Genetic variation in disease susceptibility has generally been considered to lie in the nuclear genome. Here, for the first time, I explored the influence of mitochondrial genetic (mtDNA) variation on disease susceptibility. I crossed 22 mitochondrial haplotypes onto a single nuclear genome and also studied epistasis interactions between mitochondrial and nuclear genomes (mitonuclear epistasis) by crossing five haplotypes onto five different genetic backgrounds. I found that fly susceptibility to Serratia marcescens was influenced significantly by mtDNA allelic variation. Furthermore, the effect of mitonuclear epistasis on fly susceptibility to S. marcescens was twice as great as the individual effects of either mitochondrial or nuclear genome. However, susceptibility to Beauveria bassiana was not affected by mtDNA allelic variation. These findings suggest the mitochondrial genome may play an important role in host-parasite coevolution. The Mother’s Curse hypothesis suggests that sex-specific selection due to maternal mitochondrial inheritance means that mitochondria are poorly adapted to function in males, resulting in impaired male fitness. Mother’s Curse effects have previously only been studied for two phenotypic traits (sperm-infertility and ageing) and their generality for broader life-history has not been explored. I investigated the impact of mtDNA allelic variation on 10 phenotypic traits and tested whether the patterns of phenotypic variation in males and females conformed to the expectations of the Mother’s Curse hypothesis. I found that seven of the 10 traits were significantly influenced by mtDNA allelic variation. However, there was no evidence that the effects of this variation differed between males and females. I therefore concluded that Mother’s Curse is unlikely to be a general phenomenon, nor to provide a general explanation for sexual dimorphism in life-history traits. Overall, this thesis explored the impacts of immunity costs, mitochondrial genetic variation, mitonuclear epistasis and sex-specific mitochondrial selection on D. melanogaster life-history.