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Selby, United Kingdom

Paul N.D.,Lancaster University | Moore J.P.,Lancaster University | Mcpherson M.,Stockbridge Technology Center Ltd | Lambourne C.,Stockbridge Technology Center Ltd | And 3 more authors.
Physiologia Plantarum | Year: 2012

Solar ultraviolet (UV)-B radiation (280-315 nm) has a wide range of effects on terrestrial ecosystems, yet our understanding of how UV-B influences the complex interactions of plants with pest, pathogen and related microorganisms remains limited. Here, we report the results of a series of experiments in Lactuca sativa which aimed to characterize not only key plant responses to UV radiation in a field environment but also consequential effects for plant interactions with a sap-feeding insect, two model plant pathogens and phylloplane microorganism populations. Three spectrally modifying filters with contrasting UV transmissions were used to filter ambient sunlight, and when compared with our UV-inclusive filter, L. sativa plants grown in a zero UV-B environment showed significantly increased shoot fresh weight, reduced foliar pigment concentrations and suppressed population growth of green peach aphid (Myzus persicae). Plants grown under a filter which allowed partial transmission of UV-A radiation and negligible UV-B transmission showed increased density of leaf surface phylloplane microbes compared with the UV-inclusive treatment. Effects of UV treatment on the severity of two plant pathogens, Bremia lactucae and Botrytis cinerea, were complex as both the UV-inclusive and zero UV-B filters reduced the severity of pathogen persistence. These results are discussed with reference to known spectral responses of plants, insects and microorganisms, and contrasted with established fundamental responses of plants and other organisms to solar UV radiation, with particular emphasis on the need for future integration between different experimental approaches when investigating the effects of solar UV radiation. © 2011 Physiologia Plantarum. Source


Worrall D.,Lancaster University | Holroyd G.H.,Lancaster University | Moore J.P.,Lancaster University | Glowacz M.,Lancaster University | And 4 more authors.
New Phytologist | Year: 2012

Priming of defence is a strategy employed by plants exposed to stress to enhance resistance against future stress episodes with minimal associated costs on growth. Here, we test the hypothesis that application of priming agents to seeds can result in plants with primed defences. We measured resistance to arthropod herbivores and disease in tomato (Solanum lycopersicum) plants grown from seed treated with jasmonic acid (JA) and/or β-aminobutryric acid (BABA). Plants grown from JA-treated seed showed increased resistance against herbivory by spider mites, caterpillars and aphids, and against the necrotrophic fungal pathogen, Botrytis cinerea. BABA seed treatment provided primed defence against powdery mildew disease caused by the biotrophic fungal pathogen, Oidium neolycopersici. Priming responses were long-lasting, with significant increases in resistance sustained in plants grown from treated seed for at least 8wk, and were associated with enhanced defence gene expression during pathogen attack. There was no significant antagonism between different forms of defence in plants grown from seeds treated with a combination of JA and BABA. Long-term defence priming by seed treatments was not accompanied by reductions in growth, and may therefore be suitable for commercial exploitation. © 2011 The Authors. New Phytologist © 2011 New Phytologist Trust. Source


Tilley L.A.N.,University of York | Tilley L.A.N.,Stockbridge Technology Center Ltd | Croft P.,Stockbridge Technology Center Ltd | Mayhew P.J.,University of York
Biological Control | Year: 2011

There are few examples of naturally controlled pest populations in glasshouses. Evaluating the occurrence of these systems may provide information about conditions that can promote natural enemy densities helpful to glasshouse growers. We evaluated the incidence of apparently naturally controlled populations of the algal-feeding shore fly Scatella tenuicosta Collin (Diptera: Ephydridae) over 8. weeks, in eight glasshouses in England. Across glasshouses, shore fly numbers were negatively correlated with the numbers of its parasitoid Aphaereta debilitata Morley (Hymenoptera: Braconidae), suggesting that A. debilitata may control shore flies naturally. Counterintuitively, the amount of algae present was negatively correlated with shore fly numbers, but positively correlated with numbers of the parasitoid. We therefore suggest that if growers want to encourage natural control of shore fly through A. debilitata then, contrary to conventional wisdom, algal growth should be encouraged within a glasshouse. This conservation approach to biological control could then be part of an integrated pest management programme for shore flies. This interrelationship between the pest, its food, and its natural enemy also highlights the importance of considering all trophic levels within a biological control system, even where the pest is not a direct pest of the crop. © 2010 Elsevier Inc. Source


Tilley L.A.N.,University of York | Tilley L.A.N.,Stockbridge Technology Center Ltd | Croft P.,Stockbridge Technology Center Ltd | Mayhew P.J.,University of York
BioControl | Year: 2011

Biological control efforts against the shore fly Scatella tenuicosta Collin, a pest of commercial glasshouses, have had limited success. The ability of one of its parasitoids, Aphaereta debilitata Morley, to control shore fly populations was investigated on lettuce crops within six experimental glasshouse units, over 26 weeks. The six shore fly populations, either with or without a single release of 150 mixed-sexed parasitoids, were estimated by rearing from harvested pots each week. The presence of the parasitoid significantly reduced shore fly numbers from a mean of 30.3-13.2 adult flies emerging per pot. The level of damage to each lettuce was assessed using a scoring system (0-5: no damage to heavy damage, respectively). The introduction of parasitoids reduced the median damage score of the lettuces from 2 to 1 over the study, representing a considerable change in the marketability of the crop. This study shows that single inoculative releases of A. debilitata can quickly establish within a glasshouse and significantly reduce crop damage. This suggests that the parasitoid may represent a valuable addition to an IPM strategy for shore flies. © 2011 International Organization for Biological Control (IOBC). Source

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