This study investigated commensal feeding interactions between the European harvestman (P. opilio L.) and the predatory mites Balaustium spp. and Anystis baccarum L. It also investigated the feeding behaviour of P. opilio. Experiments were conducted in the laboratory using standardised temperature, humidity, photoperiod and experimental arenas, with eggs of the brown blowfly (Calliphora stygia F.) as prey facsimiles. Due to initial difficulties in obtaining enough predatory mites, mite feeding was manually simulated piercing blowfly eggs with a minuten pin. P. opilio consumed significantly more freeze-killed than live blowfly eggs, indicating that freezing induced chemical and/or physical changes to blowfly eggs that are detected by P. opilio. Significantly more manually pierced eggs were consumed by P. opilio compared with unpierced ones, demonstrating that piercing caused a chemical and/or physical to the egg and increased the feeding rates of P. opilio. Different densities of eggs had no effect on the numbers eaten by P. opilio and placing single pierced eggs next to groups of unpierced eggs also had no effect on the numbers of unpierced eggs eaten. These results suggest that P. opilio does not exhibit klinokinesis or orthokinesis to intensify its search for prey around the area where previous prey were located. P. opilio ate significantly more brown blowfly eggs that had previously been fed on by mites, demonstrating that a short term commensal interaction existed. However, further work is required to demonstrate if the relationship is commensal in the longer term. A comparison between hand-pierced and mite-pierced eggs showed that P. opilio ate significantly more of the former indicating that mite and hand piercing were quantitatively different. The potential for, and importance of, other commensal or mutual relationships between predators in agroecosystems is discussed. The lack of klinokinesis and orthokinesis in P. opilio is compared with other predators and parasitoids that do exhibit these behaviours. The means by which prey are detected by P. opilio are discussed in relation to interpreting behaviours such as prey inspection. Concerns about the effect of pre-treatment and handling of sentinel prey and the problems of using prey facsimiles are raised.

The overall objective of this study was to test the hypothesis that insects can vector F. tumidum conidia to infect gorse plants with the aim of developing an alternative approach to mycoherbicide delivery to control weeds. Four potential insect species (Apion ulicis, Cydia ulicetana, Epiphyas postvittana and Sericothrips staphylinus) were assessed for their ability to vector F. tumidum conidia. To achieve this, the external microflora (bacteria and fungi) and the size and location of fungal spores on the cuticle of these insect species were determined. In addition, the ability of the insects to pick up and deposit F. tumidum conidia on agar was studied. Based on the results from these experiments, E. postvittana was selected for more detailed experiments to determine transmission of F. tumidum to infect potted gorse plants. The factors promoting pathogenicity of F. tumidum against gorse and the pathogen loading required to infect and kill the weed were also determined. The external microflora of the four insect species were recovered by washing and plating techniques and identified by morphology and polymerase chain reaction restriction fragment length polymorphism (PCR-RFLP) and sequencing of internally transcribed spacer (ITS) and 16S rDNA. A culture-independent technique (direct PCR) was also used to assess fungal diversity by direct amplification of ITS sequences from the washings of the insects. All insect species carried Alternaria, Cladosporium, Nectria, Penicillium, Phoma, Pseudozyma spp. and entomopathogens. Ninety four per cent of the 178 cloned amplicons had ITS sequences similarity to Nectria mauritiicola. E. postvittana carried the largest fungal spores (mean surface area of 125.9 µm²) and the most fungal CFU/insect. About 70% of the fungi isolated from the insects were also present on the host plant (gorse) and the understorey grass. The mean size of fungal spores recovered from the insect species correlated strongly with their body length (R² = 85%). Methylobacterium aquaticum and Pseudomonas lutea were common on all four insect species. Pseudomonas fluorescens was the most abundant bacterial species. In the pathogenicity trials, the effectiveness of F. tumidum in reducing root and shoot biomass of 16 and 8 wk old gorse plants was significantly increased with wounding of the plants. Older plants (32 wk old) which were wounded and inoculated were significantly shorter, more infected and developed more tip dieback (80%) than plants which were not wounded (32%). This indicates that damage caused by phytophagous insect species present on gorse through feeding and oviposition may enhance infection by F. tumidum. Wounding may release nutrients (e.g. Mg and Zn) essential for conidia germination and germ tube elongation and also provide easier access for germ tube penetration. Conidial germination and germ tube length were increased by 50 and 877%, respectively when incubated in 0.2% of gorse extract solution for 24 h compared with incubation in water. Inoculum suspensions amended with 0.2% of gorse extract caused more infection and significantly reduced biomass production of 24 wk old gorse plants than suspensions without gorse extract. A minimum number of about 900 viable conidia/infection site of F. tumidum were required to infect gorse leaves. However, incorporation of amendments (which can injure the leaf cuticle) or provision of nutrients (i.e. gorse extract or glucose) in the formulation might decrease the number of conidia required for lesion formation. Scanning electron micrographs showed that germ tube penetration of gorse tissue was limited to open stomata which partly explain the large number of conidia required for infection. The flowers and leaves were more susceptible to F. tumidum infection than the spines, stems and pods. An experiment to determine the number of infection sites required to cause plant mortality showed that the entire plant needs to be inoculated in order for the pathogen to kill 10 wk old plants as F. tumidum is a non systemic pathogen. The number of infection sites correlated strongly with disease severity (R² = 99.3%). At least 50% of the plant was required to be inoculated to cause a significant reduction in shoot dry weight. F. tumidum, applied as soil inoculant using inoculated wheat grains in three separate experiments, significantly suppressed gorse seedling emergence and biomass production. In experiments to determine the loading capacity of the insect species, E. postvittana, the largest insect species studied, carried significantly more (68) and deposited significantly more (29) F. tumidum conidia than the other species. Each E. postvittana, loaded with 5,000 conidia of F. tumidum, transmitted approximately 310 conidia onto gorse plants but this did not cause any infection or affect plant growth as determined by shoot fresh weight and shoot height. E. postvittana on its own did not cause any significant damage to gorse and did not enhance F. tumidum infection. It also failed to spread the pathogen from infected plants to the healthy ones. There was no evidence of synergism between the two agents and damage caused by the combination of both E. postvittana and F. tumidum was equivalent to that caused by F. tumidum alone. This study has shown that E. postvittana has the greatest capacity to vector F. tumidum since it naturally carried the largest and the most fungal spores (429 CFU/insect). Moreover, it naturally carried Fusarium spp. such as F. lateritium, F. tricinctum and Gibberella pulicaris (anamorph Fusarium sambucinum) and was capable of carrying and depositing most F. tumidum conidia on agar. Coupled with the availability of pheromone for attracting the male insects, E. postvittana may be a suitable insect vector for delivering F. tumidum conidia on gorse using this novel biocontrol strategy. Although it is a polyphagous insect, and may visit non-target plants, F. tumidum is a very specific pathogen of gorse, broom and a few closely related plant species. Hence, using this insect species to vector F. tumidum in a biological control programme, should not pose a significant threat to plants of economic importance. However, successful control of gorse using this "lure-load-infect" concept would depend, to a large extent on the virulence of the pathogen as insects, due to the large size of F. tumidum macroconidia, can carry only a small number of it.

A series of experiments was carried out on cultivated oat (Avena sativa L. cv Amuri) to examine the efficacies of fluazifop-butyl and glyphosate against water stressed plants, plants grown in low and high nitrogen and plants treated with gibberellic acid (GA₃). Avena sativa L. was used as a test plant and on completion of the experiments, further studies were carried out on the weed species wild oat (Avena fatua L.). In the laboratory, plants maintained at wilting point for five days before and nine days after spraying and treated with fluazifop-butyl (0.5 kg a.i./ha) appeared healthy 32 days after herbicide application, while plants supplied with water throughout the experiment were completely chlorotic/necrotic and had main stem detachment from within the leaf sheaths. In the field, plants maintained unirrigated until 14 days after spraying with fluazifop-butyl (0.25 kg a.i./ha) or glyphosate (0.18 kg a.i./ha) showed greater tolerance to the herbicides than plants irrigated regularly. Values for seed head yield for water stressed and irrigated plants, 45 days after applying fluazifop-butyl, were 66 g and zero g dryweight/m² respectively. Comparable values for glyphosate treated plants were 65 g and 25 g dryweight/m². Radiolabel studies indicated that in comparision with well watered plants, water stressed plants absorbed 20% less applied ¹⁴C-glyphosate. In addition, the proportion of absorbed ¹⁴C-glyphosate translocated from the treated leaf was 15% less under water stress conditions. Uptake of ¹⁴C-fluazifop-butyl was similar under well watered and water stress conditions and was 30-40% of that applied. The proportion of absorbed ¹⁴C-activity which was transported was very low, but was greater under well watered conditions (7.6%) than under water stress conditions (4.4%). Under well watered conditions in the laboratory and field, fluazifop-butyl (0.25 kg a.i./ha) and glyphosate (0.18 kg a.i./ha) were less toxic at low nitrogen than high nitrogen. For example, 34 days after spraying with fluazifop-butyl under laboratory conditions total plant dry weight was 1.51 g and 0.56 g at 1.0 mol/m³ and 10 mol/m³ applied nitrate respectively. As with soil water content, soil nitrogen content had no effect on uptake of fluazifop-butyl. However, the proportion of absorbed fluazifop-butyl which was translocated out of the treated lamina was greater under high nitrogen conditions (26.1 %) than under low nitrogen conditions (9.3%). Under laboratory conditions, addition of 200 µg GA₃to the leaf sheaths two days prior to spraying with fluazifop-butyl or glyphosate increased the efficacy of both herbicides at low nitrogen. Similarly, under field conditions application of GA₃ (0.21 kg/ha) two days prior to spraying with glyphosate increased the performance of the herbicide against Avena sativa L. growing in a nitrogen depleted soil. At harvest, seed head yield for GA₃ treated and non-treated plants was zero and 7.4 g dry weight/m² respectively. Experiments with Avena latua L. showed that this species was tolerant of fluazifop-butyl and glyphosate when grown in low water or low nitrogen conditions. Under water stress conditions, pre-treatment with GA₃ increased the phytotoxicity of fluazifop-butyl to Avena latua L. Similarily, GA₃ enhanced the phytotoxicity of glyphosate to Avena latua L. grown under low nitrogen conditions. Reduced performance of fluazifop-butyl under stress conditions involves a reduction in translocation of herbicide to meristems, but other factors are likely to be involved. It was concluded that for glyphosate, reductions in uptake and translocation of the herbicide are important factors causing reduced performance of this herbicide under stress conditions. Possible reasons for GA₃ enhancement of fluazifop-butyl and glyphosate activity under stress conditions are discussed and the potential of growth regulators as adjuvants is considered.

Aquesta tesi doctoral se centra en l'estudi de l'aplicació de pèptids antimicrobians en la lluita contra agents patògens de cultius de plantes d'interès econòmic.L'estratègia sintètica s'ha portat a terme utilitzant metodologies convencionals de síntesi de pèptids en fase sòlida com l'estratègia tridimensional ortogonal Fmoc/tBut/Allyl. Ha calgut fer la recerca de les condicions òptimes per a l'eliminació del grup Allyl i la ciclació. D'entre els pèptids cíclics de 4-10 aminoacids sintetitzats, el decapèptid c(Lys-Leu-Lys-Leu-Lys-Phe-Lys-Lys-Leu-Gln) ha resultat ésser el més efectiu i s'ha pres com a base per al disseny d'una quimioteca de 56 pèptids. Dels resultats obtinguts s'ha sintetitzat una segona quimioteca basada en l'estructura general c(X1-X2-X3-X4-Lys-Phe-Lys-Lys-Leu-Gln) determinada com la que posseix el millor perfil d'activitat. Els pèptids més efectius obtinguts constituixen els primers exemples de pèptids cíclics actius contra E. amylovora i poden ser considerats com a bons candidats pel desenvolupament d'agents antimicrobians efectius en protecció vegetal. / This PhD thesis was centred on the study of the application of de novo designed head-to-tail cationic cyclic peptides as inhibitors of the plant pathogenic microorganisms responsible for diseases in plants of great economic importance.The solid-phase synthesis of the cyclopeptides was carried out using a three-dimensional orthogonal Fmoc/tBut/Allyl strategy. The optimisation study of the allyl group removal and of the head-to-tail cyclization of linear peptides on SynPhase Lanterns was required for the syntheses. From the synthesized cyclic peptides of 4 to 10 residues, the cyclodecapeptide c(Lys-Leu-Lys-Leu-Lys-Phe-Lys-Lys-Leu-Gln) was the most active and has been used as parent peptide in a using a combinatorial chemistry approach. From the results, a second library based on the structure c(X1-X2-X3-X4-Lys-Phe-Lys-Lys-Leu-Gln) has been synthesized. The best cyclodecapeptides are the first examples of cyclic peptides effective against E. amylovora and make them potential candidates for the development of antimicrobial agents for use in plant protection.

After European settlement, Australian rangelands especially in South Australia underwent significant changes because of the main land use of pastoralism. Many studies have revealed that the plant communities are negatively effected by herbivory mainly by sheep. The main aim of this study is to separate the different effects of sheep, rabbits and kangaroos. This was examined by survey supported by experimental and modelling research. A 32,000 km² area previously surveyed by Tiver and Andrew (1997) in eastern South Australia was re-surveyed to monitor populations of perennial plant species at sites of various intensity of grazing by sheep, rabbits and kangaroos (goats populations are low in the study area), the most important vertebrate herbivores. Plant population data were collected in both sheep paddocks and historically ungrazed by sheep (road reserves) by using the Random Walk method and analyzed using Generalized Linear Modelling (GLM) to separate the effects of sheep and rabbits on plant regeneration and their regeneration in response to grazing. These data were also compared to similar data collected by Tiver and Andrew in 1992 (1997) to ascertain if the reduction in rabbit numbers through introduction of RCV had allowed increased regeneration. Regeneration of many species inside paddocks were negatively affected and species in roadside reserves neither did not significantly increase from 1992 to 2004. However, some species showed increase of populations in spite of sheep grazing, with some species being less susceptible than others. This research also indicates kangaroo grazing impact on some plant species. Reduction in rabbit numbers following the 1995 release of calicivirus has not been effective in restoring regeneration. Another experiment was conducted at Middleback Field Station near Whyalla to identify herbivore grazing pressure on the arid zone plant species Acacia aneura using unfenced, sheep fenced and rabbit fenced grazing exclosures. This experiment was set up with seedlings in exclosures, ten replicates of each treatment, at plots four different distances from the watering point to identify the survivorship of seedlings. Data were collected by recording canopy volumes of seedling over an 18 month period and analyzed by Residual Maximal Likelihood (REML). Seedlings both near and far from the watering point were severely effected by large herbivores, either sheep, kangaroos or both, and in a separate experiment kangaroo grazing effects on the seedling were also identified. Seedlings browsed by the rabbits were recovered better than the seedlings grazed by the large herbivores. Decreasing kangaroo activities has been noticed when the rabbit movements increased. Computer modelling was conducted to predict the future plant population structure over 500 years using a matrix population model developed by Tiver et al. (2006) and using data collected in the survey as a starting point. Extinction probabilities of populations of Acacia aneura near watering points, far from watering points and under pulse grazing scenarios were compared. Sheep grazing was found to cause eventual extinction of populations in all parts of sheep paddocks. Together, the results indicate that sheep are the major herbivore suppressing regeneration of perennial plant species. Kangaroo and rabbits have an identifiable but lesser effect. The results have implications for conservation and pastoral management. To achieve ecological sustainability of arid lands a land-use system including a network of reserves ungrazed by sheep and with control of both rabbit and kangaroo numbers will be required.

The study covered the period August 1971 to February 1975 and was conducted in three blackcurrant plots. One plot comprised mature bushes that were pruned but not sprayed during the course of the study; the other two plots were subject to full normal managerial practices including spraying. Information on various aspects of the biology was revealed and this clarified some of the areas about which little was known previously especially for the Southern Hemisphere. Fecundity is 100 eggs per female, fertility in the field is at least 97% and predation of eggs is always less than 5%. There are six larval instars. Fungi of the genera Beauveria and Cordyceps cause up to 10% mortality of the larvae. This is the first record of the latter genus infecting S. tipuliformis. A sampling plan was developed to enable estimates of the population of S. tipuliformis at various stages to be obtained. This gave information on the distribution of stages of the life cycle within the canes according to the age of the wood. These samples also permitted the construction of life tables for three generations of S. tipuliformis in one plot and one generation in the others. Replication both in space and time was therefore achieved and the results were further replicated by considering each plot as nine separate blocks. The dispersion of the egg and larval stages was tested and found to fit the negative binomial model. A common k, kc, was calculated for the egg stage and the larval c stage. Though not vital to this present study various transformations of the raw data were investigated to see which were most appropriate in order to stabilise the variance for analyses in which such suitability is vital. The logarithmic transformation based on the k parameter of the k negative model [log (x + k/2)) was the most successful. The mortality of the eggs was quite low but a significant proportion of the emerging larvae fail to colonise the pith of a cane. This mortality is density dependent. Other mortalities including winter pruning are density independent or random. The key stage of the life cycle revealed by the life tables is the adult survival. This survival and the consequent population trend index determined from the number of eggs laid was found to be affected by the prevailing weather during the flight period especially during the last week of November and the first two weeks of December.

Aim of thesis was to create an electronic version of an information database and the e-learning system, focusing on predatory insects and mites. The e-learning system provides information about the main types of predatory insects and mites used in biological plant protection, including the types of naturally occurring entomofauna and acarifauna agroecosystems in the Czech Republic. The system contains information about the taxonomy, morphology, development cycles, prey, methods of control, etc. Thesis is a combination of text, tables, photographs and line drawings from professional publications. The various components of the system are interconnected through hyperlinks. The system includes information on the ecotoxicology, dictionary terms and the ability to search based on various criteria. In the photo gallery you can find together 310 images, which are intended to create a picture of the morphology, development cycles and behavior of individual organisms.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / The production expansion areas of soybean monoculture system result in increased fertilizers and pesticides application, and the intensification of some phytosanitary problems such as the damage caused by plant-parasitic nematodes. The arbuscular mycorrhizal fungi (AMF) increase plant growth and reduce the problems caused by nematodes in soybean. The objective of this work was to study the effect of arbuscular mycorrhizal fungi Rhizophagus clarus in the growth of soybean plants and the nematode Pratylenchus brachyurus suppression. Two trials were conducted in a greenhouse. In the first experiment evaluated the growth of soybeans in the presence and absence of the mycorrhizal fungus R. clarus. In the second trial was carry out the damage caused by the P. brachyurus in soybean grown in the presence and absence of R. clarus. In soybean flowering period evaluated the height, stem diameter, the dry matter of root and shoot, nodulation, the relative chlorophyll index, the nutrient content of the plant tissue, the number of the nematode in soil and penetrated to the root system, the reproduction factor of the nematode, the number of fungal spores in the soil and mycorrhizal colonization of roots. The results showed that mycorrhiza increased the growth, nodulation and nutrient uptake of soybean plants grown in soil with or without nematode. The mycorrhizal colonization reduced the penetration of the nematode in soybean roots, despite the greater number of nematodes in the soil. The presence of the nematode influenced mycorrhizal colonization of soybean plants. The use of sustainable management practices that favor the populations of AMF in the soil, can be a strategy for increasing and/or maintaining crop yields and reducing the affect caused by the P. brachyurus. / A expansão das áreas de produção e o sistema de monocultivo da soja resultam no aumento da aplicação de fertilizantes e agrotóxicos, e na intensificação de alguns problemas fitossanitários, como os danos causados pelos fitonematoides. Os fungos micorrízicos arbusculares podem contribuir para aumentar o crescimento das plantas e reduzir os problemas causados pelos nematoides na cultura da soja. O objetivo do presente trabalho foi estudar o efeito do fungo micorrízico arbuscular Rhizophagus clarus no crescimento das plantas de soja e na supressão do nematoide Pratylenchus brachyurus. Dois ensaios foram conduzidos em casa de vegetação. No primeiro ensaio foi avaliado o crescimento da soja na presença e na ausência do fungo micorrízico R. clarus. No segundo ensaio foi avaliado os danos causados pelo nematoide P. brachyurus na cultura da soja cultivada na presença e na ausência do R. clarus. No período de florescimento da soja avaliou-se a altura, o diâmetro de colmo, a fitomassa da parte aérea e radicular, a nodulação, o índice relativo de clorofila, o teor de nutrientes do tecido vegetal, o número de P. brachyurus no solo e penetrados no sistema radicular, o fator de reprodução dos nematoides, o número de esporos fúngicos no solo e a colonização micorrízica das raízes. Os resultados demonstraram que a micorrização aumentou o crescimento, a nodulação e a absorção de nutrientes das plantas de soja, cultivadas em solo com ou sem o nematoide. A colonização micorrízica reduziu a penetração do P. brachyurus nas raízes da soja, apesar do maior número de nematoides no solo. A presença do nematoide influenciou a colonização micorrízica das plantas de soja. A adoção de práticas de manejo sustentáveis que favoreçam as populações de FMAs no solo, pode ser uma estratégia para o aumento e/ou manutenção da produtividade das lavouras e redução dos danos causado pelo P. brachyurus.

Pharmaka werden nach ihrer Einnahme bzw. Verabreichung über verschiedene Pfade in die Umwelt eingetragen. Obwohl Arzneimittel zu den toxikologisch best-untersuchten und -charakterisierten Stoffen gehören, ist ihre Wirkung auf die Umwelt und die darin lebenden Organismen weit weniger gut untersucht. Wenn in der Literatur Daten zur Ökotoxizität vorhanden sind, so beziehen sich diese meist nur auf die Wirkung von Einzelstoffen. In der Umwelt sind die Organismen jedoch gegenüber Mischungen exponiert. Aufgrund der geschilderten Problematik wurden eine Reihe von Arzneimitteln unterschiedlicher Indikationsgruppen einzeln und in Kombination mit dem Embryotest mit dem Zebrabärbling (Danio rerio, DarT) untersucht. Dieses Testsystem wurde durch Schulte & Nagel (1994) als Alternativmethode zum akuten Fischtest nach OECD 203 entwickelt und bietet den Vorteil neben letalen auch eine Reihe von subletalen Endpunkten erfassen zu können. Es handelt sich zudem nach dem deutschen Tierschutzgesetz nicht um einen Tierversuch. Die generelle Vergleichbarkeit der ermittelten Werte mit Daten aus akuten Fischtests nach OECD 203 sowie die Anwendbarkeit für verschiedenste Fragestellungen konnten in einer Reihe von Studien gezeigt werden (Nagel, 2002). Für die hier vorgestellten Untersuchungen wurden zunächst 32 Pharmaka und drei Pflanzenschutzmittel als Einzelstoffe mit dem DarT untersucht. Basierend auf den Ergebnissen der Einzelstofftests wurden Mischungen sowohl aus Substanzen mit ähnlichen als auch unähnlichen Wirkmechanismen getestet. Es zeigte sich, dass unabhängig vom Wirkmechanismus die Mischungstoxizität durch das Konzept der Konzentrationsadditivität gut vorhergesagt wurde, während das Konzept der Unabhängigen Wirkung die Mischungstoxizität unterschätzte. Ebenfalls konnte gezeigt werden, dass die Kombination der Stoffe auf Basis der NOEC, die im DarT anhand der Herzschlagfrequenz nach 48 Stunden ermittelt wird, zu deutlichen Mischungseffekten führt.

In this thesis, experiments were conducted in the laboratory and the field to determine whether the provision of floral resources to hoverflies could enhance the biological control of aphids. The overall aim was to clarify hoverfly behaviour and ecology in an agroecosystem in order to understand the potential of these insects for biocontrol under a conservation biological control (CBC) regime. A preliminary experiment in New Zealand compared the effect of different coloured water-traps on catches of the hoverflies Melanostoma fasciatum (Macquart) and Melangyna novaezelandiae (Macquart). Significantly more individuals were caught in completely yellow traps than in traps with green outer walls and yellow inner walls or in completely green traps. This suggested that if a measure of hoverfly numbers relating to a particular distance along a transect is required, consideration should be given to the ability of hoverflies to detect yellow traps from a distance. The use of traps that are green outside would more accurately reflect the local abundance of hoverflies, as the insect would be likely to see the yellow stimulus only when above or close to the trap. Also, the addition of rose water significantly increased the number of M. fasciatum caught. From a suite of flowering plants chosen for their ability in other studies to increase hoverfly visit frequencies, laboratory experiments were conducted in France to determine the plant’s effectiveness at enhancing Episyrphus balteatus (De Geer) ‘fitness’, and to evaluate whether adult feeding on flowers was related to performance. Phacelia (Phacelia tanacetifolia Bentham cv. Balo), followed by buckwheat (Fagopyrum esculentum Moench cv. Katowase) and coriander (Coriandrum sativum L.) gave the optimal reproductive potential of female E. balteatus. There was no correlation between pollen and nectar consumption, and there was no discernible positive correlation between the quantity of pollen ingested and the resulting female performance. Phacelia and buckwheat were then studied as resource subsidies in the field in New Zealand. The effect of incorporating phacelia or buckwheat in the margins of 5 m x 5 m broccoli plots was tested for hoverfly activity and floral ‘preferences’. Hoverflies which had fed on phacelia and buckwheat pollen were found up to 17.5 m from the floral strips and females of M. fasciatum and M. novaezelandiae consumed more phacelia pollen than that of buckwheat in the field. These results support the choice of phacelia as an ideal floral resource subsidy in crops for enhanced biological control by these New Zealand species. The need for studying hoverfly movement in a large-scale field experiment was apparent from the field studies, so the next experiment was carried out in a field 450 × 270 m and flies were marked via their ingestion of the pollen of phacelia. The focus was on the proportion of flies having consumed the pollen. Although large quantities of pollen were found in some hoverfly guts, most did not contain phacelia pollen and very few were captured at 50 m from phacelia, compared with numbers at the border of the floral strip. A possible explanation was that hoverflies feed on a large variety of pollen species, reducing the relative attraction of phacelia flowers. Another possibility was that hoverflies dispersed from the phacelia away from the crop. Also, pollen digestion rates are likely to be a factor. Finally, a series of experiments was conducted in the field and laboratory to study hoverfly efficacy through oviposition and larval behaviour. In field experiments, female M. fasciatum and M. novaezelandiae laid more eggs where buckwheat patches were larger; however higher oviposition rates did not lead to improved aphid population suppression. In greenhouse experiments, larvae of E. balteatus could initiate a decline in aphid numbers at the predator: prey ratio 1: 8.3, however this control did not persist. Experiments in the laboratory showed that hoverfly larvae became more active and left the system while aphid numbers declined or numbers of larvae increased. This behaviour was caused by two factors: hunger and avoidance of conspecific larvae. Further experiments showed that the avoidance of conspecifics was caused by mutual interference rather than cannibalism. The results of this work highlight the importance of hoverfly dispersal ability. Given the observations of foraging behaviour of females and mutual interference observed between larvae, and the lack of success in CBC by hoverflies in experiments at the crop scale, it is essential to assess the impact of insect predators and parasitoids at a landscape scale.