Knowledge for a sustainable world

MA , PhD

Dr Sarah Arnold joined the University of Greenwich in 2010, after completing her PhD in sensory ecology in the Chittka Lab at Queen Mary, University of London. Her background at Queen Mary and prior to that at the University of Cambridge, was in pollinator behaviour (Dyer et al. 2006, Nature) and the evolution of flower colours (Arnold et al. 2010, PLoS ONE). Dr Arnold investigated trends in the colour composition of flowering plant communities, and the responses of bees to flower colours under variable light conditions, finding that bees show preferences for familiar illuminant types when foraging (Arnold et al. 2012, J Exp Biol).

Since joining the Natural Resources Institute (NRI), Dr Arnold has continued to develop her interest in pollinators, studying the effects of the composition of pollen and nectar (Arnold et al. 2014, J Chem Ecol) on pollinators, and is currently also involved in the CocoaPOP (Cocoa Pollination for Optimised Production) project, collaborating with scientists in the Caribbean to understand and enhance cocoa pollination. Additionally, she works on the ecology and behaviour of stored product pests, investigating the factors determining how they orient towards food material (Arnold et al. 2012, PLoS ONE) and the potential of pesticidal plants and other control methods to protect stored commodities in low-income countries. Dr Arnold is particularly interested in how the behaviour of storage pests can be affected by their own life history (e.g. age, morph) and interactions between different cue types (colour, odour).

Dr Arnold is a member of NRI's Agriculture, Health & Environment Department, working primarily with the pest behaviour, chemical ecology and ecosystems services research groups. She been lead or co-author on publications about flower colour evolution, and pollinator and storage pest behaviour in international peer-reviewed journals, and is one of the developers and managers of the Floral Reflectance Database.

Dr Arnold is interested in insect behaviour and ecology, in particular the interactions between economically important insects (pests, pollinators, etc.) and their food sources. Key research questions that interest her include:

  • How do pests of stored products orient towards host material?
  • How do they respond behaviourally to attractive and repellent cues, including pesticidal plants and other possible control strategies?
  • Understanding which plants are also attractive or repellent, and why (the compounds responsible) will allow optimised design of control methods.
  • How do pollinating insects identify food using visual information and other cues, such as the effects of plant appearance or variable illumination on foraging technique?
  • What happens when they find that food: how does the composition of different plants' nectar and pollen affect pollinator preferences and fitness?
  • Ecology of pollinators in the UK and abroad. In particular at present, the diversity, natural history and behaviour of fly pollinators (Ceratopogonid midges) in Caribbean cocoa plantations in the Caribbean, and how to safeguard and improve pollinator numbers to increase yields on farms.

CocoaPOP - Cocoa Pollination for Optimised Production

EU-EDF funded project (ACP) in collaboration with University of Trinidad and Tobago, CABI and Cocoa Industry Board (Jamaica).

This is a three-year project studying the ecology of cocoa pollinating midges (Diptera: Ceratopogonidae) in the Caribbean, focusing on the diversity of species and the size of populations currently present, how these change over the year, and how they can been increased and safeguarded. Little work has been carried out on Caribbean cocoa pollination in several decades, and cocoa agronomy has changed during that time. The work involves sampling of midges on cocoa plantations, investigating their attraction to cocoa flowers, and experimental interventions to increase the numbers present on plantations. The ultimate aim is to increase cocoa yields to provide increased income to cocoa farmers. Work on the project so far has provided training in insect identification skills to students and researchers in Trinidad and Tobago, and monthly sampling of the insect fauna of cocoa estates is ongoing in order to map the diversity and variability of small Diptera in these environments.

Host orientation behaviour in stored product insects

Dr Arnold has worked on this theme as part of University of Greenwich-funded projects such as Ecology of host seeking behaviour among stored product beetles. The aims of these projects have been to study different elements of how stored product pests orient towards food sources (smallholder farmers' commodity stores) using odour and colour cues, and how pesticidal plants can be optimally deployed to achieve control through physiological and behavioural methods. Dr Arnold's work has focused particularly on the major cereal pests Rhyzopertha dominica, Prostephanus truncatus and Sitophilus zeamais and the legume pest Callosobruchus maculatus. This work has used specialist equipment for investigating insect behaviour including the four-arm olfactometer (Arnold et al. 2012) and the Syntech ServoSphere and has resulted in conference presentations and a publication in PLoS ONE detailing the key finding that adults of C. maculatus do not all respond consistently to the odour of host material (cowpea); the strength of response depends on variables including the sex and age of the beetle and whether it is of the dispersal flight-capable morph or the more fecund flightless morph. Several additional publications are currently in preparation.

A bitter disappointment? Do alkaloids influence pollination success in crops?

This University of Greenwich-funded project focused on crop lupins (grown in Europe and South America to provide food for humans and livestock), and their naturally-produced herbivory defence compounds. The alkaloids in lupins also occur in the nectaries and pollen, and therefore can be collected and consumed by insect pollinators. This project investigated the effects this may have on the pollinators, but focused on both adult bees and also the larvae, which consume the majority of the pollen. A publication is anticipated soon. Future work is likely to include further work on plant-pollinator interactions, particularly on more diverse effects of pollen and nectar composition on pollinator behaviour, fitness and pollination efficiency, as well as focus on pollination ecology in low-income countries.

  • Member of the Royal Entomological Society
  • Member of the British Ecological Society
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